text:
\section{Introduction}\label{s:intro}

As nurseries in which planets form, protoplanetary discs are all-important in setting the
boundary conditions for planet formation. One of their most important characteristics is
the disc lifetime because once the gaseous component has dispersed, giant planet
formation is halted. Therefore, the lifetime of protoplanetary discs and how they
disperse has been the focus of many studies
\citep[e.g.][]{1995Natur.373..494Z,2001MNRAS.328..485C,2001ApJ...553L.153H,2004ApJ...612..496M,2004ApJ...611..360A,2012ApJ...756..133C}
and sets hard constraints for models of giant planet formation.

The nature of the transition from a gaseous protoplanetary disc to a relatively gas-free
debris disc is poorly understood, particularly the impact on the formation and evolution
of planets and planetesimals. Observations at a range of infrared (IR) wavelengths are
therefore vital to build up possible evolutionary sequences. Near/mid-IR observations
probe dispersal and the creation of inner holes in gas-rich ``transition'' discs
\citep{1990AJ.....99.1187S,2010ApJ...708.1107M,2012ApJ...747..103E}, and are also
sensitive to warm dust created during the later stages of terrestrial planet formation
\citep[e.g.][]{2010ApJ...717L..57M,2012MNRAS.tmp.3462J}. Far-IR observations are most
sensitive to changes in the outer regions of protoplanetary discs as dust grains settle
and grow, and to the same $\sim$100AU scales at which debris discs are typically observed
around main-sequence stars.

For some evolved objects it is not clear whether the stars are still dispersing their gas
and are in the ``transition'' phase, or if the disc is sufficiently gas-free that it can
be considered a true debris disc. Perhaps the best example is the extremely bright disc
around HD~98800B \citep[$L_{\rm disc}/L_\star \approx 2\%$,][]{1993ApJ...406L..25Z},
which has been treated as either by different authors and illustrates that classification
is not straightforward \citep{2007ApJ...664.1176F,2007ApJ...658..569W}. The recent
discovery of H$_2$ emission, a signature of gas accretion, seems to favour the transition
disc interpretation \citep{2012ApJ...744..121Y}. Of course, there will be a continuum of
objects between relatively gas-rich and gas-free discs, and no disc could ever be
considered truly devoid of gas, but in order to create a useful evolutionary sequence it
is important to interpret individual objects carefully. Doing so will, for example,
ensure that unlikely scenarios are not invoked where simpler ones will suffice, and that
observational sequences of objects are as close to reality as possible.

Here, we study an object that we suggest lies at the late end of the transition to a
gas-free debris disc. HD~166191 has been known to have an IR excess above the expected
photospheric level since it was observed with IRAS and MSX
\citep{1992A&AS...96..625O,2005MNRAS.363.1111C}. The possibility of confusion of the IRAS
emission with another nearby source, which is visible to the South-West in higher
resolution images, meant that the excess was only detected unambiguously from
8-20~$\mu$m. More recently, this system was suggested to have a mid-IR excess with both
WISE \citep{2013MNRAS.433.2334K} and AKARI \citep{2013A&A...550A..45F}, which was
confirmed with high resolution mid-IR imaging \citep{2013arXiv1308.0405S}. While these
studies went in search of warm terrestrial-zone debris discs, only
\citet{2013arXiv1308.0405S} used the Multi-band Imaging Photometer for \emph{Spitzer}
\citep[MIPS,][]{2004ApJS..154....1W,2004ApJS..154...25R} to show that the far-IR emission
is probably associated with the star, and therefore that the disc emission is significant
over a wide range of wavelengths.

We previously argued that this star hosts a gas-rich disc based on the breadth of the
disc spectrum and its brightness relative to the star \citep{2013MNRAS.433.2334K}, but
the other studies \citep{2013A&A...550A..45F,2013arXiv1308.0405S} have interpreted it as
hosting a debris disc with two components (i.e. analogous to the Asteroid and
Edgeworth-Kuiper belts seen in our Solar System). Here we use several lines of evidence
to argue that HD~166191 does indeed host a gaseous protoplanetary disc. After discussing
the observations in \S \ref{s:obs}, we show in \S \ref{s:age} that HD~166191 has a common
space motion with the $\sim$4~Myr-old Herbig Ae star HD~163296 suggesting that HD~166191
has a similar age. In \S \ref{s:rt} we highlight some potential issues with the debris
disc interpretation and show that the HD~166191 disc emission is well modelled by a
relatively normal transition disc, as might be expected for such a young star. Finally,
we compare the HD~166191 disc to others, taking a close look at the 10~$\mu$m silicate
feature and the overall disc spectrum, and discuss the implications of our work in \S
\ref{s:disc}.

\section{Observations}\label{s:obs}

HD~166191 is an 8.4th magnitude star that lies 119pc from the Sun
\citep{2007A&A...474..653V} in the direction of the Galactic center. The Michigan
spectral type is F4V, though using new data we suggest below that the star is actually
closer to a late-F or early G-type, similar to the F8 spectral type found by
\citet{2013arXiv1308.0405S}. The star was detected by both Hipparcos and 2MASS, which we
combine with $BVRI$ photometry from \citet{1984ApJS...55..389M} to fit a stellar
photosphere model. We fitted PHOENIX AMES-Cond models \citep{2005ESASP.576..565B} using
least-squares minimisation, finding an effective temperature of $6170 \pm 50$K. A wealth
of photometry exists for HD~166191, and is tabulated by \citet{2013arXiv1308.0405S} and
shown in Figure \ref{fig:phot}, including new \emph{Herschel} observations described
below. We do not use the WISE $4.6\mu$m (W2) measurement, as this is known to be
overestimated for bright
sources.\footnote{http://wise2.ipac.caltech.edu/docs/release/allsky/expsup/sec6\_3c.html}

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{sed.eps}
    \caption{Photometry (dots) and the 6170K PHOENIX AMES-Cond photosphere model (blue
      curve) for HD~166191.}\label{fig:phot}
  \end{center}
\end{figure}

\subsection{New observations}\label{ss:newobs}

To ensure that the far-IR excess was not confused in the MIPS 70~$\mu$m observations and
to constrain the disc size we obtained 70 and 160~$\mu$m observations with PACS instrument
\citep{2010A&A...518L...2P} on the Herschel Space Observatory \citep{2010A&A...518L...1P}
in March 2013. In addition, we obtained ground-based optical, near, and mid-IR spectra
with the goal of better characterising the star and the near/mid-IR excess.

\subsubsection{SSO 2.3m WiFeS}\label{ss:sso}

We observed HD~166191 with the Wide Field Spectrograph
\citep[WiFeS,][]{2007Ap&SS.310..255D} on the ANU 2.3m telescope at Siding Spring
Observatory. Flux calibrations are performed according to \citet{1999PASP..111.1426B}
using spectrophotometric standard stars from \citet{1992PASP..104..533H} and
\citet{1999PASP..111.1426B}. A full description of the instrument configurations and data
reduction procedure can be found in \citet{2013AJ....145....5P}. We use the
$\lambda/\Delta\lambda = R = 3000$ blue arm spectrum to estimate the stellar effective
temperature by comparison with model atmospheres. The method compares the spectrum with
synthetic spectral models, with extra weight given to regions that are sensitive to
surface gravity, and is described in detail by \citet{2013arXiv1306.0624B}. Assuming
Solar metallicity we obtain an effective temperature of $5965 \pm 100$K, in reasonable
agreement with the value drived from broadband photometry above. The gravity is found to
be $\log g = 3.4 \pm 0.25$, suggesting that HD~166191 has not yet reached the
main-sequence (see \S \ref{s:age}).

In the WiFeS $R = 7000$ red arm spectrum Li\,\textsc{i} absorption at 6708\AA~(an
indicator of youth in Solar type stars, see \S \ref{s:age}) is detected with an
equivalent width of $150 \pm 20$m\AA. From these observations we also obtained a radial
velocity of $-10.1 \pm 1$km s$^{-1}$, in agreement with $-8.1 \pm 1.3$km s$^{-1}$
reported by \citet{2013arXiv1308.0405S}. Hydrogen $\alpha$ and $\beta$, and Sodium
doublet absorption is seen, so any gas accretion, which would result in emission
\citep[e.g.][]{2001ApJ...550..944M}, is below a detectable level
\citep[$\lesssim$10$^{-10}$ to $10^{-11}M_\odot {\rm yr}^{-1}$,
e.g.][]{2003ApJ...592..266M,2006AJ....132.2135S}.

\subsubsection{IRTF/SPeX}\label{sss:spex}

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{spex.eps}
    \caption{IRTF SpeX and BASS spectra, and a 6170K model atmosphere convolved to
      approximately the same resolution. Filled blue dots show observed photometry and
      open circles show synthetic photometry of the spectra for comparison, where
      possible (MSX 12$\mu$m, and IRAC 3.5 and 4.5~$\mu$m). The SPeX spectra is
      normalised to 2MASS J. Regions of large telluric absorption where the spectrum may
      be adversely effected are blocked out in grey. A small IR excess may be visible
      beyond about 2.1~$\mu$m in the SPeX spectrum, and clearly visible in the BASS
      spectrum. The difference between the IRAC 3.5 and 4.5~$\mu$m photometry and the
      equivalent spectrophotometry from BASS are significantly different, and indicate
      probable variability in the excess spectrum.}\label{fig:spex}
  \end{center}
\end{figure}

To further characterise the near-IR part of the excess, near-infrared spectral
measurements from 0.8 to 2.5~$\mu$m were obtained using the SpeX instrument on the 3 m
NASA Infrared Telescope Facility (IRTF) located on Mauna Kea, Hawaii. It was operated in
single prism mode (R=250). Frames were taken so that the object was alternated between
two different positions (usually noted as the `A' and `B' positions) on a $0.8 \times 15$
arcsec slit aligned North-South. Two A0V stars were observed for telluric corrections,
HD~168707 and HD~170364. Argon lamps were used for wavelength calibration. 24 images were
taken with 1 second exposures and 10 coadds and 16 images were taken with 0.5 second
exposures and 10 coadds. The airmass ranged from 1.41 to 1.47 during the observations.

The spectrum is shown in Figure \ref{fig:spex}, along with a 6170K model atmosphere
(i.e. the same stellar model used in Figure \ref{fig:phot}). At 2MASS $K_s$ and beyond
the possible onset of the IR excess is seen. An excess at these wavelengths is expected
given that an excess is confidently detected beyond 3~$\mu$m.

By comparing the spectrum with the \citet{2009ApJS..185..289R} spectral atlas the
spectral type appears to be late-F or early G-type. The Paschen $\delta$, $\gamma$, and
$\beta$, and Brackett $\gamma$ lines are clearly visible in the spectrum, and the atlas
shows that these are present in F9V stars but less clear by G2V. Based on these lines and
the effective temperatures derived above, we assign HD~166191 a G0V spectral type, with
an uncertainty of one-two subtypes.

\subsubsection{AEOS/BASS}

Observations were obtained using the Aerospace Corporation's Broadband Array Spectrograph
System \citep[BASS,][]{1990SPIE.1235..171H} instrument on the 3.67 m Advanced Electro
Optical System (AEOS) telescope on Haleakala, Hawaii. This instrument uses a cold beam
splitter to separate the light into two separate wavelength regimes. The short-wavelength
beam includes light from 2.9 to 6~$\mu$m, while the long-wavelength beam covers
6-13.5~$\mu$m. Each beam is dispersed onto a 58 element blocked impurity band linear
array, thus allowing for simultaneous coverage of the spectrum from 2.9-13.5~$\mu$m. The
spectral resolution is wavelength dependent, ranging from about $R = 30$ to 125 over each
of the two wavelength regions. The simultaneous coverage of the entire 3-13~$\mu$m region
that BASS provides has played a critical role in the investigations of the clearing of
the inner discs \citep{2002ApJ...568.1008C,2004ApJ...614L.133B,2008ApJ...678.1070S}.

The BASS data were calibrated using $\alpha$ Lyrae and $\beta$ Peg and cleaned of
residual telluric (CO$_2$ and H$_2$O) contamination, but that of O$_3$ at 9.7 $\mu$m was
left in. The spectrum is shown in Figure \ref{fig:spex} and shows a clear silicate
feature around 10~$\mu$m and is in good agreement with the T-ReCS photometry presented in
\citet{2013arXiv1308.0405S}. In addition, the absolute calibration of BASS spectra is
known to be better than about 5\% \citep{basscalib}, meaning that we can test for
differences between the BASS spectrum and the older IRAC data (2006) at 3.5 to 4.5~$\mu$m
(also shown in Figure \ref{fig:spex}). The BASS/IRAC flux ratios in these bands are 1.32
and 1.38, with significances of 3.1 and 4.5$\sigma$, indicative of significant
variability in the excess spectrum. \citet{2013arXiv1308.0405S} note the possibility of
variability based on the difference between IRAC and WISE photometry at $4.6\mu$m, but
WISE is known to overestimate fluxes for bright sources in this band (see first
footnote).

\subsubsection{Herschel}

Following identification of this object in \citet{2013MNRAS.433.2334K}, we obtained a
Director's time observation of HD~166191 using the PACS instrument onboard
\emph{Herschel} (ObsIDs: 1342267772/3). We used a slightly non-standard mini-scan map,
designed to be wide enough to cover both HD~166191 and the nearby source that
contaminates the IRAS photometry. The flux density of both objects was measured by
fitting a model beam (an observation of $\gamma$ Dra) at each location. We found fluxes
of $1.7 \pm 0.1$Jy and $0.75 \pm 0.1$Jy at 70 and 160~$\mu$m for HD~166191, consistent
with the \emph{Spitzer} photometry at 70~$\mu$m presented by
\citet{2013arXiv1308.0405S}. This observation further confirms that HD~166191 has a
significant far-IR excess (see Figure \ref{fig:phot}) and because the emission is
point-like (with beam size $\sim$5\arcsec) an approximate upper limit on the source
diameter is $\sim$5\arcsec, or about 600AU.

\subsection{Summary of observations}

Based on previous data and the new observations described above we assign the star a
spectral type of G0V. An IR excess is clearly visible beyond 3~$\mu$m, with a clear
10~$\mu$m silicate feature. A significant discrepancy between the IRAC and BASS
observations at 3-5~$\mu$m suggests that the disc emission is variable, which is not
unusual for transition discs
\citep{2009ApJ...706L.168B,2009ApJ...704L..15M,2011ApJ...728...49E}. The very large disc
luminosity ($L_{\rm disc}/L_\star \approx 10$\%), the fact that the excess spectrum
extends over a wide range of wavelengths (Fig \ref{fig:phot}), and the probable
variability suggests at first glance that the emission is probably from a young
($\lesssim$10~Myr old) star that hosts a gas-rich protoplanetary disc. However, it is also
known that some debris disc brightnesses vary
\citep[e.g.][]{2012ApJ...751L..17M,2012Natur.487...74M,2013MNRAS.433.2334K}, and an
alternative interpretation could be that HD~166191 hosts an unusually bright debris disc
with both warm and cool components \citep{2013A&A...550A..45F,2013arXiv1308.0405S}, in
essence an extreme analogue of the two-component debris disc around $\eta$ Corvi
\citep{2005ApJ...620..492W,2009A&A...503..265S}. The most promising way to discern
between these possibilities and to find a self-consistent explanation is to determine the
age of HD~166191.

\section{The age of HD~166191}\label{s:age}

There are several techniques available to infer the ages of young stars
\citep[e.g.][]{2004ARA&A..42..685Z,2010ARA&A..48..581S}. In this section we attempt to
refine the age of HD~166191 using the empirical methods of lithium depletion and X-ray
activity, combined with kinematic considerations and (model-dependent) isochrone
placement.

Because it is efficiently destroyed in stellar interiors, photospheric lithium abundance
can serve as a mass-dependent clock over pre-main sequence ages
\citep{2004ARA&A..42..685Z,2013MNRAS.435.1325M}. Our Li\,\textsc{i} $\lambda$6708
equivalent width, $150\pm 20$~m\AA, agrees with the high-resolution value reported by
\citet{2013arXiv1308.0405S} ($120\pm5$~m\AA). At the spectral type of HD~166191 this
value is consistent with an age less than the Pleiades
\citep[$\lesssim$100~Myr;][]{2004ARA&A..42..685Z}. The poor age constraint of lithium
depletion in Solar-type stars is due to their radiative cores effectively separating the
convective outer layers from the hotter interiors, preventing lithium depleted material
from reaching the photosphere.

X-ray emission is another common diagnostic of stellar youth, a manifestation of the
strong magnetic fields and fast rotation rates observed in young stars
\citep[e.g.][]{1999ARA&A..37..363F}. HD~166191 was not detected in the \emph{ROSAT}
All-Sky X-ray Survey (RASS).  The RASS 0.1--2.4 eV limiting flux \citep[$2\times10^{-13}$
erg cm$^{-2}$ s$^{-1}$;][]{1995ApJ...450..392S} at 119~pc implies an X-ray to bolometric
luminosity ratio of $\log(L_{X}/L_{\rm bol})\lesssim-4.8$. \citet{2013arXiv1308.0405S}
report a detection in the XMM-Newton Serendipitous Source Catalog
\citep{2009A&A...493..339W}, which yields a 0.2--12 eV luminosity of $2.4\times10^{29}$
erg s$^{-1}$ and $\log(L_{X}/L_{\rm bol})\approx -4.9$. Ignoring the subtleties of
comparing results from different X-ray observatories and energy bands, we compare these
values to the results of \citet{2005ApJS..160..390P}, who examined the mass-dependence of
X-ray emission in young stars in Orion as a function of age. Their distributions shows
that while HD~166191 is one of the X-ray faintest 1-$2M_\odot$ stars at 1-10~Myr ages, the
X-ray luminosity also varies by about 2 orders of magnitude at a given age. Comparison
with the X-ray luminosity distribution in \citet{2011MNRAS.412...13O} leads to the same
conclusion. Therefore, though it is indeed X-ray faint as noted by
\citet{2013arXiv1308.0405S}, we do not consider this faintness to provide a significantly
stronger age constraint than the lithium absorption.

\begin{figure*}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=1\textwidth]{uvwxyz.eps}
    \caption{Heliocentric velocity (top) and position (bottom) of HD~166191 (black dot,
      with errors), compared to members of nearby associations and moving groups from
      \citet{2008hsf2.book..757T}: Tuc-Hor (orange circles), AB Dor (green squares),
      Argus (red open squares), $\beta$ Pic (cyan stars), Carina (yellow crosses),
      Columba (blue open circles), $\epsilon$ Cha (red triangles), Octans (blue open
      stars) and TW Hya (green filled triangles). Positions \citep[shaded
      ellipses;][]{2000ApJ...544..356M} and velocities \citep{2011ApJ...738..122C} of the
      three Scorpius-Centaurus OB association subgroups are also plotted: Upper Sco
      (darkest, triangle), Upper Cen-Lup (inverted triangle) and Lower Cen-Cru (lightest,
      diamond). The large open circle in the shows the velocity and position of
      HD~163296.}\label{fig:uvwxyz}
  \end{center}
\end{figure*}

Kinematics are commonly used to assign young stars to moving groups or associations of
known age. From \emph{Hipparcos} astrometry \citep{2007A&A...474..653V} and the
2.3-m/WiFeS radial velocity we calculate a heliocentric space motion for HD~166191 of
$(U,V,W)= (-7.6\pm1.0, -22.4\pm3.0, -7.6\pm1.2)$~km~s$^{-1}$. This agrees with the velocity
presented by \citet{2013arXiv1308.0405S} from Tycho-2 proper
motions. Figure~\ref{fig:uvwxyz} shows the position and velocity of HD~166191 compared
other nearby young stars. While the star's space motion is consistent with members of
several young stellar associations, including the Scorpius-Centaurus OB association
(Sco-Cen), its relatively large distance (119$_{-14}^{+19}$~pc) and low Galactic latitude
yields a heliocentric position, $(X,Y,Z)=(+118\pm18, +15\pm2, -4\pm1)$~pc, distinct from
other young groups in the solar neighbourhood.

Like \citet{2013arXiv1308.0405S}, we searched for \emph{Hipparcos} entries around
HD~166191 with similar proper motions and parallaxes and found a match with the
well-studied `isolated' Herbig Ae star HD~163296
(119$_{-10}^{+12}$~pc). \citet{2013arXiv1308.0405S} used the XHIP
\citep{2012AstL...38..331A} radial velocity ($-4.0\pm3.3$~km~s$^{-1}$) for HD~163296 from
\citet{1930ApJ....72...98M} via \citet{2006AstL...32..759G}. This is the mean velocity of
a single line (Mg\,\textsc{ii} $\lambda$4481) from seven Mt.\,Wilson plates
($\sigma_{RV}=9.4$~km~s$^{-1}$). More recently, \citet{1965MNRAS.130..281B} and
\cite{2013MNRAS.429.1001A} reported larger velocities of $-11$~km~s$^{-1}$\ and $-9\pm6$~km~s$^{-1}$,
respectively. Using the latter value and \emph{Hipparcos} astrometry we calculate a space
motion of $(U,V,W)= (-6.0\pm6.0, -22.3\pm2.1, -7.4\pm0.8)$~km~s$^{-1}$, in excellent agreement
with HD~166191.

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{isochrones.eps}
    \caption{Colour-magnitude diagram of HD~166191 and HD~163296, with 3--20~Myr
      theoretical isochrones from \citet{2000A&A...358..593S} and
      \citet{2012MNRAS.427..127B} for comparison. For HD~163296, photometry and a
      (circumstellar) extinction of $E(B-V)=0.15$ were adopted from
      \citet{2012A&A...538A..20T}. The Tycho-2 $V$-band magnitude for HD~166191 was
      transformed to the Johnson-Cousins system using the relations of
      \citet{2000PASP..112..961B}. No extinction was adopted for
      HD~166191.}\label{fig:cmd}
  \end{center}
\end{figure}

A colour-magnitude diagram (CMD) of both stars is plotted in Fig.\,\ref{fig:cmd}. If
HD~166191 and HD~163296 are co-eval then they should lie along the same theoretical
isochrone in such a diagram. Compared to PARSEC \citep{2012MNRAS.427..127B} and
\citet{2000A&A...358..593S} isochrones, HD~163296 has an age of 4--5~Myr, consistent with
previous isochronal age estimates from a variety of model grids
\citep{2011MNRAS.410..190T,2012A&A...538A..20T,2013MNRAS.429.1001A}. HD~166191 falls
slightly older, with an age of 5--10~Myr. This age agrees with the (conservative)
$5_{-3}^{+25}$~Myr CMD age reported by \citet{2013arXiv1308.0405S} using the PARSEC
models and 2MASS $K_{s}$ magnitudes. We adopted the $J$-band photometry to minimise the
effects of disc emission observed in both stars at wavelengths greater than 2 $\mu$m (see
\S \ref{sss:spex}). The derived masses of HD~166191 are 1.7 and $1.6M_\odot$ from the
PARSEC and \citet{2000A&A...358..593S} isochrones respectively. Neither star shows signs
of unresolved binarity \citep{2012A&A...538A..20T,2013arXiv1308.0405S}. Given their
proximity (7.5 pc in space), identical distances, congruent space motions and very
similar ages, it is likely HD~166191 and HD~163296 form a co-eval, co-moving pair of
$\sim$4-5~Myr-old stars. HD~163296 was proposed as an outlying member of the
10--20~Myr-old Sco-Cen subgroup Upper Cen-Lup by \citet{2008ApJ...678.1070S}. This
membership is unlikely considering its young age and heliocentric position and velocity
(Fig.\,\ref{fig:uvwxyz}). Instead, we speculate that HD~166191 and HD~163296 may
represent the first members of a yet-to-be-discovered kinematic association or new
Sco-Cen subgroup.

Having now established the likely youth of HD~166191 using a CMD and by association with
HD~163296, it seems that a less extreme interpretation for the large IR excess may be
that of a gaseous transition disc, in contrast to the debris disc interpretation of
\citet{2013arXiv1308.0405S}.

\section{Disc modelling}\label{s:rt}

\subsection{A two-belt debris disc?}\label{ss:2b}

The interpretation favoured by \citet{2013arXiv1308.0405S} is that HD~166191 hosts a warm
terrestrial zone debris disc, the result of collisions between planetesimals or planets
during the late stages of planet formation. However, the total fractional luminosity
$f=L_{\rm disc}/L_\star$ of the excess spectrum is about 10\%, meaning that the dust in a
putative debris disc must capture at least this much of the starlight. If the dust has a
non-negligible albedo or is optically thick along the line of sight the fraction of
starlight captured must be higher. As we show below, because such extreme IR excesses may
require optically thick dust, significantly more than 10\% of the starlight may need to
be captured. An additional complication in the case of HD~166191 is that
\citet{2013arXiv1308.0405S} infer a cool outer component based on the breadth of the
emission spectrum, with a fractional luminosity similar to the inner component. While
such a two-belt structure is of course possible (e.g. the Solar System has two belts),
the extreme brightness of the HD~166191 disc means that the inner belt must capture
$\sim$6\% of the starlight, yet be sufficiently optically thin or misaligned that the
outer belt is still able to capture $\sim$4\%. These constraints set lower limits on the
vertical extent of the inner and outer belts, which can be compared with observations of
edge-on belts around other stars.

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{opang.eps}
    \caption{Simple model of allowed opening angles for a coplanar two-belt
      interpretation of HD 166191 with $f_{\rm i}=0.06$ and $f_{\rm o}=0.04$. The dashed
      lines show how the radial optical depth of the inner belt depends on the opening
      angle. The observed fractional luminosity cannot be produced for opening angles in
      the shaded regions (where $\tau_{\rm i,o}>1$). The solid lines show constant radial
      optical depth for the outer belt (eq \ref{eq:outer}). The dotted line shows where
      the belts have equal opening angles.}\label{fig:opang}
  \end{center}
\end{figure}

To make a simple model of the above picture we assume that i) the two belts are coplanar,
ii) have uniform density, iii) the dust in the belts has negligible albedo, iv) the belts
are optically thin from the viewing direction, and v) reemission from either belt does
not heat the star or the other belt. We use parameters $f_{\rm i,o}$ and $\theta_{\rm
  i,o}$ for the fractional luminosity and opening angle of the inner (i) and outer (o)
belts respectively.

The radial optical depth of inner belt, $\tau_{\rm i}$, is related to the opening angle
by
\begin{equation}\label{eq:inner}
  f_{\rm i} = \tau_{\rm i} \sin( \theta_{\rm i} / 2)
\end{equation}
That is, the fraction of starlight captured by the inner belt, and hence the fractional
luminosity, is the radial optical depth multiplied by the fraction of the sky that it
covers as seen by the star. When it is optically thick, increasing the radial optical
depth does not increase the belt brightness (i.e. in equation \ref{eq:inner}, $\tau_{\rm
  i} \le 1$), so the opening angle of the inner belt must be at least 7$^\circ$. The
radial optical depth is correspondingly lower if the opening angle is larger, with a
lower a limit of 0.06 if the belt is a spherical shell (i.e. $\theta_{\rm i}=180^\circ$).

The outer belt is always shadowed by the inner belt to some degree. If the opening angle
of the outer belt is less than that of the inner belt, all light illuminating the outer
belt must pass through the inner belt, with the light attenuated by a factor $1-\tau_{\rm
  i}$ (with a minimum value of zero). If the inner belt is fatter than the outer belt,
then only a fraction of the light heating the outer belt is intercepted by the inner
belt, and the outer belt thickness is independent of the inner belt thickness (for fixed
$f_{\rm i}$). In these two regimes, the radial optical depth of the outer belt,
$\tau_{\rm o}$ (also $\le$1), is related to its opening angle and the inner belt
properties by
\begin{equation}\label{eq:outer}
  f_{\rm o} = \left\{ \begin{array}{ll}
      \tau_{\rm o} (1-\tau_{\rm i}) \sin( \theta_{\rm o}/2) & \theta_{\rm o} < \theta_{\rm i} \\
      \tau_{\rm o} \left( \sin( \theta_{\rm 0}/2) - f_{\rm i} \right) & \theta_{\rm o} > \theta_{\rm i}
    \end{array}
  \right.
\end{equation}

These relations are shown by the solid lines in Figure \ref{fig:opang}, which uses the
parameter space of $\theta_{\rm o}$ vs. $\theta_{\rm i}$. Dashed lines show constant
inner belt optical depth, where the minimum inner belt opening angle is set by $\tau_{\rm
  i} = 1$. The solid lines show equation (\ref{eq:outer}) for three different inner belt
optical depths. There are two different regimes for each line; if $\theta_{\rm o} <
\theta_{\rm i}$ the outer belt is fully shadowed by the inner and there is a tradeoff
between the opening angles of each, the thinner the inner belt the more it shadows the
outer belt due to increased optical depth, and the thicker the outer belt must be. This
regime is shown by the curved part of the solid lines. If $\theta_{\rm o} > \theta_{\rm
  i}$ the outer belt is thicker than the inner and changes in the inner belt thickness do
not change the outer belt brightness. That is, a thicker inner belt occults the outer
belt more, but is less optically thick for the same fractional luminosity. The $\tau_{\rm
  o}=1$ line tends towards, but never reaches $2\sin^{-1}f_{\rm o} \approx 5^\circ$ for
large $\theta_{\rm i}$, which would be the minimum opening angle in the absence of the
inner belt.

Therefore, if both belts are to be relatively thin the minimum opening angles allowed by
this simple analysis are about 7$^\circ$ for the inner component, and $\sim$12$^\circ$
for the outer belt (i.e. the left end of the lowest solid line). This minimum assumes
that both components are radially optically thick, and that no light is lost to
scattering, the latter being a reasonable approximation given that typical albedoes for
small bodies in the Solar System and in other debris discs are $\sim$10\%
\citep[e.g.][]{2005Natur.435.1067K,2008DPS....40.6108M,2009AJ....138..240F,2010AJ....140.1051K}. The
other two solid lines show that even for larger opening angles the belts must have
relatively large radial optical depths, purely due to the high fractional luminosity.

There are few debris discs where the opening angles can be measured, though a wealth of
information is available for the Solar System. The inclinations of Asteroid belt objects
vary widely, with most objects below 10$^\circ$ (an opening angle of 20$^\circ$), and
similar values for Kuiper belt objects. Similarly, the full-width at half-maximum
brightness opening angle of the $\beta$ Pictoris disc is $\sim$10$^\circ$ at about 130AU
\citep{2006AJ....131.3109G}, and the AU Microscopii disc is even thinner at
$\sim$5$^\circ$ \citep{2005AJ....129.1008K}. Therefore, the opening angles inferred for
the inner and outer HD~166191 disc components are comparable with observed
discs. However, this similarity requires that both components are radially optically
thick \emph{and} optically thin in the viewing direction, or the opening angles must be
larger. For a typically inclined viewing geometry ($\sim$60$^\circ$) such a configuration
is unlikely, so unless the disc components are much more radially extended than they are
vertically, and the system is viewed face-on, the opening angles are probably larger then
our estimated minimum. The star is not seen to be reddened, and given the large optical
depths seen in Figure \ref{fig:opang} the star is very probably seen directly and not
obscured by the disc. In summary, this comparison is suggestive that the two-belt debris
model requires relatively large optical depths for reasonable opening angles, but does
not strongly argue against such an interpretation.

Now considering the plausibility of the debris disc interpretation in terms of a
collisional model, the central issue is the lifetime of such extreme levels given the
$\sim$5~Myr age of HD~166191. As noted by \citet{2013arXiv1308.0405S}, the dust lifetime
due to collisions at about 1AU is only a few years so they must be replenished; a
late-stage planetary embryo impact or ongoing collisions in a massive Asteroid-belt
analogue are the possible sources. While either the inner or outer disc component could
be the result of a collision analogous to the Earth-Moon forming event, the extremely
bright period that follows such a collision is probably short lived. The length of this
period is uncertain due to the possibility of non-axisymmetry and an inability to remove
dust at high optical depth, but given the rapid evolution shown in Figure 14 of
\citet{2012MNRAS.tmp.3462J}, less than 100-1000 years seems a reasonable estimate. If the
outer belt is several times more distant the emission will decay more slowly, by roughly
a few orders of magnitude. Therefore, for a 5~Myr old star it may be unlikely to observe
short lived bright dust emission. However, this star was of course picked from a large
sample of stars due to its extremely bright excess and several giant collisions are
expected during terrestrial planet building
\citep[e.g.][]{1998Icar..136..304C,2004Icar..168....1R,2006AJ....131.1837K}

The alternative scenario suggested by \citet{2013arXiv1308.0405S} is dust resulting from
ongoing collisions in a massive Asteroid belt. The issue here is the same as above; such
extreme brightness requires a significant mass in large objects to generate a large
surface area of dust, but this mass (and hence space density) also requires that the
collisions between the large objects are very frequent. Indeed,
\citet{2007ApJ...658..569W} showed using a simple collision model that the maximum
fractional luminosity for young stars is $\sim$0.1\% (see their Figure 3). Alternatively,
using equation 21 of \citet{2007ApJ...658..569W}, to maintain a fractional luminosity
above 6\%, the maximum time the inner belt has been evolving for is of order 1,000 years,
with a few orders of magnitude uncertainty \citep[see also][]{2010MNRAS.401..867H}.

Another consideration for the massive Asteroid-belt analogue scenario is the disc
mass. \citet{2013arXiv1308.0405S} estimate the mass in dust present in the inner belt to
be roughly $10^{20}$ to $10^{23}$g. However, because the debris disc interpretation
explicitly implies that this mass is replenished by destruction of larger objects, the
dust mass is a negligible fraction of the total mass for typical debris disc size
distributions \citep[e.g.][]{1969JGR....74.2531D,2003Icar..164..334O}. Using equation 15
from \citet{2008ARA&A..46..339W} we can calculate the total mass present in a size
distribution from 1~$\mu$m sized grains up to 100km objects using a standard differential
size distribution slope of -3.5. Converting the 760K and 175K temperatures of the belts
\citep{2013arXiv1308.0405S} to radii of 0.3AU and 6AU, and using the fractional
luminosities of 0.06 and 0.04 yields total masses of 1.7 and 400$M_\oplus$ for the inner
and outer belts respectively. For reference, the minimum mass contained in the Solar
nebula was a few hundred Earth masses \citep[e.g.][]{1977Ap&SS..51..153W} so the inferred
mass for the outer belt is very large, if relatively large planetesimals are assumed. For
our assumed $dn(a) \propto a^{-3.5} da$ particle size distribution, the total mass scales
as the square root of the maximum size, so for much smaller 10m planetesimals, the mass
is also much smaller at $4M_\oplus$. However, the collisional lifetime calculated above
is also a function of planetesimal size ($\propto \sqrt{D}$) and assumed $D=2000$km, so
the outer belt lifetime for such small planetesimals would be of order 1000
years. Therefore, there is a trade-off between planetesimal size and disc lifetime,
meaning that either the disc is relatively massive, or its lifetime at the curent
brightness is very short.

In summary, we cannot rule out the debris disc interpretation of
\citet{2013arXiv1308.0405S}. We have shown i) that dust replenished by collisions either
requires near optically thick belts or relatively large disc opening angles and ii) that
the outer belt is relatively massive if it is the result of ongoing collisions or has a
very short lifetime. HD~166191 was selected as potentially interesting from a parent
population of $\approx$24,000 Hipparcos stars \citep{2013MNRAS.433.2334K} and is
therefore a rare object within this sample, meaning that arguments against the debris
disc interpretation that rely on HD~166191 being observed at a special time may not be
robust. As we have noted however, there is another possible interpretation; a
protoplanetary disc made up of both gas and dust, as is seen around many stars that have
similar ages to HD~166191.

\subsection{A transition disc?}\label{ss:rt}

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{rtmod.eps}
    \caption{Protoplanetary transition disc model for HD~166191. Red dots show photometry
      and grey squares the BASS spectrum. The black solid line shows the best fitting
      model as described in the text.}\label{fig:rtmod}
  \end{center}
\end{figure}

To test whether HD~166191 can be modelled as a protoplanetary disc we modelled the
observed spectral energy distribution (SED) using the Monte Carlo Radiative transfer code
MCFOST \citep{2006A&A...459..797P,2009A&A...498..967P}. Here, we used a parametric disc
extending from an inner radius $R_{\rm in}$ to an outer radius $R_{\rm out}$. With this
approach, the model is of a dust disc that is implicitly well mixed with the gas that
makes up most of the total mass in the disc. The dust density distribution has a Gaussian
vertical profile, and the dust surface density profile and the scale height are defined
as power-law distributions with $\rho (r, z) = \rho_0 (r) \exp(-{z^2} / 2{h^2}(r)),
\Sigma (r) = \Sigma_0 (r / r_0)^{-p}$ and $ h(r) = h_0 (r / r_0)^{\beta}$, respectively,
where $r$ is the radial coordinate in the equatorial plane and $h_0$ is the scale height
at a fiducial radius $r_0$ = 100 AU. The dust grains are assumed to be homogeneous and
spherical amorphous silicates with a differential grain size distribution of the form
$dn(a) \propto a^{-3.5}da$, between a minimum grain size $a_{\rm min}$ and a maximum
grain size $a_{\rm max}$. The dust extinction and scattering opacities, scattering phase
functions, and Mueller matrices are calculated using Mie theory.

In order to fit the SED data, we first searched for a satisfactory solution by hand,
which was used as the starting point for an automated best fit search with a Genetic
Algorithm. In the absence of strong constraints from direct imaging (the \emph{Herschel}
observations require $R_{\rm out} \lesssim 300$ AU), we have set the external radius
$R_{\rm out}= 25$ AU. This value is not well constrained by the SED modelling, in
particular because of the lack of photometric data longer than 160 $\mu$m. The parameters
of the best fitting solution are presented in Table \ref{tab:parameters} and the
resulting SED is presented in Figure \ref{fig:rtmod}. The fit to the data is sufficiently
good to show that the HD~166191 spectrum can be interpreted as a protoplanetary disc.

A prominent feature of the SED is the 10 $\mu$m silicate emission, though we did not
thoroughly explore the mineralogical composition of the disc. However, to better match
the general profile of the 10 $\mu$m feature we added a fraction of crystalline silicates
\citep{2001ApJ...550L.213L} to the dust mixture. The crystalline silicates have a size
distribution ranging from 0.03 to 5 $\mu$m. The amorphous silicates \citep[of olivine
stoichiometry,][]{1995A&A...300..503D} have a size distribution ranging form 0.03 to 9
$\mu$m. This value for the maximum size of the amorphous silicates is poorly constrained
because of the lack of data longer than 160 $\mu$m. Both species are distributed
similarly in the disc. The Genetic Algorithm found the best model for a composition made
of 18\% of crystalline silicates, similar to the fraction of warm crystalline silicates
found by \citet{2010A&A...520A..39O} in a study of 58 T Tauri stars with IRS spectra.

The resulting model requires the scale height to be about 4 AU at $r=100$ AU (or
$h/r=0.04$). This is smaller than the ``standard'' protoplanetary disc models that
usually have $h/r \sim 0.1$, indicating that the dust has settled towards the midplane
\citep[e.g.][]{2011ApJS..193...11M,2011ApJ...742...39S}. The derived inner radius of
0.95~AU suggests that the disc has an inner hole, which along with the lack of detectable
accretion (\S \ref{ss:sso}) is consistent with a several Myr old object that has started
the transition from a full protoplanetary disc to a debris disc. The inner hole size is
smaller than most transition discs, but a wide range of sizes is seen
\citep[e.g.][]{2012ApJ...747..103E,2011ApJ...732...42A} so a $\sim$1~AU hole is not
particularly remarkable. The far-IR disc emission level is the main indicator of
settling, which can be significantly brighter in other transition discs (see fig
\ref{fig:speccomp} below), suggesting that the progression towards the debris disc phase
is more advanced for HD~166191 \citep[e.g.][]{2011ApJ...742...39S}.

\begin{table}
  \begin{center}
    \caption{Parameters of the best-fit model}
    \label{tab:parameters}
    \begin{tabular}{lcc}
      \hline\hline
      Parameter & explored & best\\
      & range & value  \\
      \hline
      \multicolumn{3}{c}{Stellar parameters} \\
      \hline
      $T_{\rm eff}$ (K) & fixed  & 6000 \\
      $R_{\rm star}$ ($R_\odot$) & fixed & 2.13 \\
      $A_V$ & fixed & 0.0 \\
      Distance (pc) & fixed &  119 \\
      \hline
      \multicolumn{3}{c}{Disc parameters} \\
      \hline
      M$_{\rm dust}$  ($M_\odot$) & 10$^{-7}$ -- 10$^{-4}$ & $5 \times 10^{-6}$ \\
      $R_{\rm out}$ (AU) & fixed & 25   \\
      $R_{\rm in}$ (AU)  & 0.1 -- 5.0 & 0.95 \\
      $\beta$ & 1.0 -- 1.3 & 1.12 \\
      p & -2.0 --  -0.1 & -0.8 \\
      h$_0$ (AU, \@r=100AU) & 1.0 -- 15.0 & 3.8 \\
      inclin. (deg.) & 0.0 -- 90.0 & $<60$ \\
      a$_{\rm min}$ ($\mu$m) & fixed  &  0.03  \\
      a$_{\rm max-amorph}$ ($\mu$m) & 0.5 -- 1000.0  &  9.0  \\
      Amorph. to Cryst. ratio & 1.0 -- 0.7 & 0.82 \\
      \hline
    \end{tabular}
  \end{center}
\end{table}

\section{Discussion}\label{s:disc}

Perhaps the biggest clue to the status of HD~166191 is the common space motion with the
well known Herbig Ae star HD~163296. As outlined in \S \ref{s:age}, this association
suggests that HD~166191 has a similar $\sim$4-5~Myr age to HD 163296, and these stars may
represent the first few members of a yet-to-be discovered association or
Scorpius-Centaurus subgroup that comprises many more lower-mass stars.

The implication for HD~166191 itself is that the star probably hosts a protoplanetary
disc rather than an exceptionally bright debris disc. The young age does not of course
require that the disc is primordial, but places HD~166191 in the $<$10~Myr age range
where Sun-like stars are seen to host such discs
\citep[e.g.][]{2007ApJ...667..308C,2009ApJS..181..197C,2011ARA&A..49...67W}. While we
cannot rule out the extreme debris disc interpretation, we have noted potential issues
(\S \ref{ss:2b}), and suggest that the disc is actually gas-rich. Our protoplanetary disc
interpretation is corroborated by the fact that the disc spectrum is consistent with a
fairly standard model for a protoplanetary disc (see \S \ref{ss:rt}). The spectrum shows
evidence for clearing in the innermost regions, as expected given typical evolutionary
sequences, and grain settling in the outer regions, both signatures of discs whose
evolution is well advanced beyond their initial state, as would be expected for a
$\sim$5~Myr old star.

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{midircomp.eps}
    \caption{Comparison of the mid-IR emissivity of HD~166191 with other protoplanetary
      (HD~100546 and HD~163296), and debris (HD~113766A) discs, and comet Hale Bopp. The
      emissivity is calculated by dividing the spectrum by a blackbody at the approximate
      temperature of the continuum emission
      \citep[e.g.][]{2008ApJ...673.1106L}.}\label{fig:midircomp}
  \end{center}
\end{figure}

Further clues to the nature of the disc lie in the BASS spectrum, which is compared to
other discs and comet Hale Bopp's coma in Figure \ref{fig:midircomp}. Here we have
divided each spectrum by a blackbody at the appropriate temperature to produce
``emissivity'' spectra, which far better show spectral features common to objects
emitting at different temperatures.\footnote{Using the temperatures of 250 \& 135K
  \citep[HD~100546,][]{2007Icar..187...69L}, 300K (HD~163296), 700K (HD~166191), 200K
  \citep[Hale Bopp,][]{2007Icar..187...69L}, and 440K
  \citep[HD~113766A,][]{2008ApJ...673.1106L}.}  Of particular note here is the similarity
between the HD~166191 and HD~163296 peaks around 10~$\mu$m. Compared to HD~113766A,
another candidate for ongoing terrestrial planet formation, the HD~166191 silicate peak
is broader and is not double peaked.

Such differences in the shape of the silicate feature are diagnostic of the grain sizes
and composition, which can subsequently be related to their evolutionary state. One
approach is to derive compositions for objects of a range of age via modelling, and then
comparing the results in terms of an evolutionary sequence. For example,
\citet{2008ApJ...673.1106L} showed that their derived values for the olivine to pyroxene
ratio change with age. \citet{2012ApJ...747...93L} show the olivine to pyroxene ratio and
total olivine fraction derived from modelling for 19 objects in their Figure 7. Older
objects have greater olivine fractions, both in absolute terms and relative to pyroxene,
with HD~163296 appearing as one of the least evolved objects and HD~113766A appearing as
a moderately evolved object. Therefore, because the spectrum of HD~166191 appears very
similar in shape to HD~163296, and different to HD~113766A, the evolutionary state of the
HD~166191 dust appears more primordial. This conclusion would of course be strengthened
by detailed modeling of a 5-35 $\mu$m spectrum, as was done for the other systems in Fig
7, which allows for verification of the 8-13 $\mu$m silicate identifications using the
secondary 16 - 33 $\mu$m silicate features. We thus look forward to obtaining a detailed
spectrum of the HD166191 system in the 13 - 30 $\mu$m range, e.g. with JWST.

\begin{figure}
  \begin{center}
    \hspace{-0.5cm} \includegraphics[width=0.5\textwidth]{spcomp.eps}
    \caption{Comparison of HD~166191 with other protoplanetary (RY~Tau, GM~Aur) and
      debris (HD~113766A, HD~181327) discs. Data compiled from: RY Tau, GM Aur
      \citep{2007ApJS..169..328R}, HD~113766A
      \citep{2008ApJ...673.1106L,2013A&A...551A.134O}, and HD~181327
      \citep{2012A&A...539A..17L}, using \emph{Spitzer} InfraRed Spectrograph
      \citep[IRS,][]{2004ApJS..154...18H} spectra from the CASSIS database
      \citep{2011ApJS..196....8L}.}\label{fig:speccomp}
  \end{center}
\end{figure}

The overall disc spectrum should also be put in context with entire disc spectra at other
stages to better picture HD~166191 as part of a possible evolutionary sequence. Figure
\ref{fig:speccomp} compares the overall 0.5 - 160 $\mu$m HD~166191 SED with some examples
of other protoplanetary and debris discs around (approximately) Sun-like stars, all
scaled to a similar photospheric level at 2$\mu$m, with the exception of RY~Tau for which
the photosphere is not visible at this wavelength. We have not attempted to correct the
shorter wavelength photometry for reddening as we are here concerned with the longer
wavelengths. These represent something of an evolutionary sequence; (i) the youngest
discs, represented here by RY~Tau \citep{2008A&A...478..779S}, have a relatively flat
spectral slope across near/mid-IR wavelengths, but at the onset of disc dispersal (ii) an
inner hole develops and the spectrum has a flux deficit in the mid-IR and little change
in the far-IR and sub-millimetre flux \citep[e.g. GM~Aur,][]{2005ApJ...630L.185C}, the
final debris disc phase (iii) begins when the gas disc is dispersed, and generally the
disc has a spectrum that is typically very similar to a pure blackbody
\citep[e.g. HD~181327,][]{2012A&A...539A..17L}, but in some rare cases shows significant
levels of warm emission, which is commonly interpreted as a sign of terrestrial planet
formation \citep[e.g. HD~113766A,][]{2008ApJ...673.1106L,2013A&A...551A.134O}. Both
protoplanetary and debris discs show solid-state 10~$\mu$m silicate features, so their
presence or otherwise does not indicate the evolutionary state in this broad comparison
(though as discussed above their shape is important).

Within the context of this simple evolutionary sequence, HD~166191 shows characteristics
that might individually be attributed to either a transitional or a debris disc. The disc
shows evidence for an inner hole with little near-IR dust emission, though the hole is
probably not as large or well cleared as for GM Aur given the larger mid-IR excess. In an
inside-out evolution picture such as photoevaporation
\citep[e.g.][]{2001MNRAS.328..485C}, the HD~166191 disc might be considered less evolved
than GM Aur in the inner regions. However, as we note below it may be that the inner
emission is being enhanced by dust produced during terrestrial planet formation, which
could happen before and/or after an inner hole develops. A significant difference with GM
Aur is a lower level of far-IR and sub-millimetre excess, suggesting that the HD~166191
disc is significantly less flared as a result of a lower disc mass and/or dust grains
settling to the disc midplane.

Indeed, comparison of the HD~166191 far-IR emission with HD~181327, a young ($\sim$10~Myr)
bright debris disc, shows that the two have similar levels of excess, and that both are
lower than ``typical'' protoplanetary discs such as RY Tau and GM Aur. This comparable
level of far-IR flux suggests that in addition to being less flared, that the HD~166191
disc could be well advanced in the transition to a debris disc in the outer
regions. Similarly evolved discs have been observed around lower mass stars
\citep[e.g. in Corona Australis,][]{2013A&A...551A..34S}, suggesting that such a spectrum
is not particularly unusual. For example, in the $F_{24}/F_{100}$ vs. $F_{24}$ diagram of
\citet{2013A&A...551A..34S} (their Figure 11), HD~166191 would lie among the ``Depleted
discs'', indicating significant evolution and lower scale heights. How far advanced the
transition to the debris disc phase is will require a gas detection or stringent limits.

Finally, comparing HD~166191 with HD~113766A, a bright warm debris disc, the 0.5 - 160
$\mu$m spectrum continua look very similar; HD~113766A plausibly looks like a somewhat
more evolved and fainter version of HD~166191. Given that HD~166191 can be modelled as a
transition disc, such a comparison suggests that the interpretation of HD~113766A, which
has thus far been classed as a debris disc,
\citep[e.g.][]{2008ApJ...673.1106L,2012MNRAS.422.2560S,2013A&A...551A.134O}, deserves
further consideration. For example, it may be that the two-component structure inferred
from the combination of mid-IR interferometry \citep{2012MNRAS.422.2560S} and far-IR
photometry \citep{2013A&A...551A.134O} is actually indicative of an inner disc that is
significantly extended, as might be expected for a protoplanetary disc. However,
\citet{2006ApJS..166..351C} set stringent limits on gas levels in the inner regions of
the HD~113766A disc using the IRS spectrum, and the dust emission may therefore not be
primordial without gas to protect it from radiation forces. In addition, we have already
argued that HD~113766A appears more evolved based on the mid-IR silicate feature (Figure
\ref{fig:midircomp}). This possibility leads us to a third interpretation for the
HD~166191 disc (that also applies to HD~113766A) that we have not yet considered; a
combination of scenarios where the outer disc is still gaseous with significantly settled
dust, while the inner regions are in the late stages of, or have already made, the
transition to the debris phase. In this case the excess might be again thought of as
comprising two components; an inner warm component due at least in part to ongoing
terrestrial planet formation (but perhaps also the remnants of the protoplanetary disc),
and a well settled outer component with residual gas. Remnant gas may help maintain dust
levels produced by collisions, reducing the timescale problems that arise in the debris
disc scenario, where dust is removed easily by radiation forces.

Following such a phase, it may be that large cool discs such as HD~181327 emerge as the
inner regions collide and decay, and are then observed around older stars as ``typical''
(i.e. longer lived) debris discs at radii of tens to hundreds of AU. There are several
possible scenarios for this sequence however. For example, HD~166191 could already host a
debris disc that lies inside the protoplanetary disc and is currently undetectable, but
will emerge as the protoplanetary disc continues to disperse. Alternatively, it may be
that the birth of a debris disc requires stirring of planetesimals to sufficient
velocities through formation of large protoplanets, so the HD~166191 spectrum may in the
future drop to much fainter levels, but then become brighter again once the debris phase
begins \citep[e.g.][]{2004AJ....127..513K,2008ApJ...672..558C}

The single most important difference between the scenarios we have discussed, and the
fundamental difference between our transition disc interpretation and the debris disc
interpretation of \citet{2013arXiv1308.0405S}, is the presence or absence of gas.  While
the BASS spectrum is more similar to protoplanetary discs and argues that the silicate
emission is relatively primordial, this signature comes from dust. A disc that is still
in transition to the debris disc phase will have some remaining gas, while a true debris
disc will have negligible gas. There is currently no evidence for gas in the HD~166191
disc, either from gas accretion onto the star nor directly from the disc (e.g. from
near-IR CO emission in the SPeX spectrum). Indeed, one apparent reason
\citet{2013arXiv1308.0405S} reject the $\sim$5~Myr age suggested by the CMD in favour of
an older 10-100~Myr age is based on the lack of H$\alpha$ emission. However, many young
stars with protoplanetary discs are not seen to accrete gas, particularly transition
discs \citep[e.g.][]{2010ApJ...710..597S} and accretion is not necessarily expected
during this phase either \citep[e.g.][]{2006MNRAS.369..229A}. Detection, or a strongly
constraining non-detection, of gas around HD~166191 is therefore an obvious way in which
the disc may be further characterised.

\section{Summary}

HD~166191 has been known to host an infrared excess for several decades, but the origin
of this excess was unclear. New surveys by the AKARI and WISE telescopes have led to
renewed interest, and suggestions that the excess is due to a rare bright debris disc
\citep{2013A&A...550A..45F,2013arXiv1308.0405S} or an evolved protoplanetary disc
\citet{2013MNRAS.433.2334K}.

Though we cannot rule out the debris disc interpretation, we argue that the excess is
most simply interpreted as a relatively normal protoplanetary transition disc. This
conclusion is supported by our findings that i) HD~166191 is very likely associated and
co-eval with the previously isolated $\sim$4~Myr old Herbig Ae star HD~163296, ii) the
disc spectrum can be modelled by a protoplanetary transition disc, and iii) the mid-IR
silicate feature is a good match to other young objects, such as HD~163296. This finding
may represent the first hint of a new nearby young stellar association or subgroup of
Scorpius-Centaurus.

By comparing HD~166191 with other known protoplanetary and debris discs, we argue that
the HD~166191 disc is more evolved than most transition discs, and suggest some possible
scenarios for the late stages of the protoplanetary to debris disc transition.

\section{Acknowledgements}

We thank the referee for a careful reading of the manuscript and comments that improved
the article. This work was supported by the European Union through ERC grant number
279973 (GMK \& MCW). SJM is supported through a Gliese Fellowship at the University of
Heidelberg's Zentrum f\"{u}r Astronomie. FM acknowledges support from the Millennium
Science Initiative (Chilean Ministry of Economy), through grant ``Nucleus
P10-022-F''. FED acknowledges support by NASA under Grant No. NNX12AL26G issued through
the Planetary Astronomy Program.

redpajama_set_name: RedPajamaArXiv


Capacitive liquid level sensors work by measuring capacitance of the probe which is immersed into the liquid or even placed around the tank (which in that case must be non-metallic). Depending on amount of liquid between probe electrodes, the resulting capacitance will be different which can be detected by electronics and used to calculate level or volume of liquid inside a tank.
This project is based on Arduino board and the probe is made with kitchen aluminium foil which is in this case wrapped around a plastic bottle. It uses CapSense library which needs just one resistor and two microcontroller pins. After calibrating and taking measurement, the resulting value is calculated to either height or volume of liquid.


text:
Biogeosciences, 11, 217–235, 2014
https://doi.org/10.5194/bg-11-217-2014
Research article 21 Jan 2014
Research article | 21 Jan 2014
Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals
T. W. Hilton*,1, K. J. Davis1, and K. Keller2 T. W. Hilton et al. T. W. Hilton*,1, K. J. Davis1, and K. Keller2
1Department of Meteorology, Pennsylvania State University, University Park, PA, USA
2Department of Geosciences, Pennsylvania State University, University Park, PA,, USA
*now at: School of Engineering, University of California, Merced, Merced, CA, USA
Received: 27 Jul 2013 – Discussion started: 22 Aug 2013 – Revised: 25 Nov 2013 – Accepted: 09 Dec 2013 – Published: 21 Jan 2014
Abstract. Global terrestrial atmosphere–ecosystem carbon dioxide fluxes are well constrained by the concentration and isotopic composition of atmospheric carbon dioxide. In contrast, considerable uncertainty persists surrounding regional contributions to the net global flux as well as the impacts of atmospheric and biological processes that drive the net flux. These uncertainties severely limit our ability to make confident predictions of future terrestrial biological carbon fluxes. Here we use a simple light-use efficiency land surface model (the Vegetation Photosynthesis Respiration Model, VPRM) driven by remotely sensed temperature, moisture, and phenology to diagnose North American gross ecosystem exchange (GEE), ecosystem respiration, and net ecosystem exchange (NEE) for the period 2001 to 2006. We optimize VPRM parameters to eddy covariance (EC) NEE observations from 65 North American FluxNet sites. We use a separate set of 27 cross-validation FluxNet sites to evaluate a range of spatial and temporal resolutions for parameter estimation. With these results we demonstrate that different spatial and temporal groupings of EC sites for parameter estimation achieve similar sum of squared residuals values through radically different spatial patterns of NEE. We also derive a regression model to estimate observed VPRM errors as a function of VPRM NEE, temperature, and precipitation. Because this estimate is based on model-observation residuals it is comprehensive of all the error sources present in modeled fluxes. We find that 1 km interannual variability in VPRM NEE is of similar magnitude to estimated 1 km VPRM NEE errors.
How to cite: Hilton, T. W., Davis, K. J., and Keller, K.: Evaluating terrestrial CO2 flux diagnoses and uncertainties from a simple land surface model and its residuals, Biogeosciences, 11, 217–235, https://doi.org/10.5194/bg-11-217-2014, 2014.

redpajama_set_name: RedPajamaCommonCrawl


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text:
Sail Meridian
The beginning of our Grand Adventure... or folly... we'll let you know!
20 January 2010 | Brisbane, Australia
24 December 2009 | Brisbane, Australia
Merry Chrissy from Brissy
12 December 2009 | underway
Last Passage
22 November 2009 | Noumea, New Caledonia
Writing in Sand
Baguettes and Brie
07 November 2009 | Ile Uere, New Caledonia
Passage to New Cal
05 November 2009 | Espirito Santo, Vanuatu
Asanvari Bay
21 October 2009 | Aore Island, Vanuatu
Aore Island
19 October 2009 | Peterson Bay, Espirito Santo
Oyster Island
09 October 2009 | Espirito Santo
Port Vila and Uliveo
25 September 2009 | Tanna, Vanuatu
Things That Go Boom in the Night
11 September 2009 | Vuda Point, Viti Levu, Fiji
Boring Update
13 August 2009 | Navadra, Fiji
Exploring the Yasawas
24 July 2009 | Malolo Lailai, Fiji
Here in Musket Cove
29 June 2009 | Yadua Island, Fiji
Yadua Adventure
Savusavu to Yadua
10 June 2009 | Savusavu, Fiji
Bula!
Weather Update
19 May 2009 | Whangamumu, New Zealand
Yes, they said it couldn't be done but we finally made it to Fiji.
Our passage from Opua, New Zealand was fairly uneventful and at times even pleasant(!) Oh sure, at times the wind was too light to sail, but we had no qualms about firing up the "iron genny" (that's the engine, of course) to keep our speed up. After all we didn't want that nice weather window slamming shut 200 miles from Fiji. And yeah, sometimes the sea was a bit rolly (as Glen on Tin Soldier likes to say, "A bit of a rock and roll show") but it wasn't bad enough to drive me crazy. And the rest of the time we were sailing in 10-20 knots of wind with relatively flat seas, so you really can't ask for better than that. We even managed to catch a couple of Mahi Mahi's along the way. We really feel that we got off easy because boats that left before us got beat up in heavy weather and those that were just a little bit behind us ended up with winds of 25 knots right on the nose- that doesn't make for a comfortable ride.
So after nearly 8 days of this "mixed bag" we were approaching our destination and we realized that at our present speed we would arrive at the pass into Savusavu Bay during the night- we felt it wouldn't be prudent to enter until daylight so when we got in the lee of Koro Island we hove-to (sort of) for about 10 hours. (Heaving-to means setting up the sails and rudder to oppose each other and is a way of essentially "parking" the boat mid-ocean. Heaving-to is most often employed by sailors during heavy weather as a way of giving the boat and crew a break from bashing around in rough conditions but in this instance it was just a way to stop for a while.) Because we were close to land (and to Tin Soldier!) and not in the open ocean we had to watch our drift. Even though Meridian was no longer sailing, we were still drifting south along the length of Koro. After a couple of hours we would turn the boat around and sail back up to the northern tip, then heave-to again and slowly drift down for another couple of hours. As Marilyn on Tin Soldier remarked, our chartplotter track looked like an "Etch-a-Sketch". Around 3:00am we started sailing again and sailed the last 30 miles into Savusavu Bay on the island of Vanua Levu.
Fiji is an archipelago comprised of over 300 islands and islets. The two largest islands are Viti Levu and Vanua Levu. About half of all Fijians are indigenous Fijian, a mixture of Polynesian and Melanesian. The other half are Indo-Fijians: fourth- or fifth-generation descendants of indentured laborers. Regardless, whether indigenous or indo- we have been happily impressed with how friendly the Fijians are. As we walk down the street we are often greeted with a bright smile and a hearty "Bula!" which means "Hello! Cheers! Welcome!" all at once.
So we've been here for about a week, trying to acclimatize to the heat and humidity (my sweat glands have been going into overdrive!) and enjoying very inexpensive meals ashore. Marilyn and I have declared to Glenn and John that since we can eat ashore cheaper than on the boat we don't believe it would be wise to use up our provisions cooking meals aboard until we are out at some deserted anchorage. I think they bought it.
Our plan was to leave Savusavu today or tomorrow and make our way west to Yadua Island and then to the Yassawa island group. But guess what? Some friendly local cruiser just told us about this low pressure system that is due to hit the islands in the next couple of days, possibly bringing up to 50 knots of wind with it. Can you believe it?!!! Here we are waiting for weather AGAIN!
Vessel Name: Meridian
Vessel Make/Model: Tayana 48CC
Hailing Port: Napa, CA
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text:
La Facultad de Humanidades y Ciencias de la Educación es una institución universitaria pública y laica uruguaya la cual forma parte de la Universidad de la República. Cuenta con 4726 estudiantes matriculados, según el VII Censo de Estudiantes Universitarios de la República, de 2012.
Se encuentra ubicada en la ciudad de Montevideo, sobre la calle Magallanes 1577.

Historia
La entonces Facultad de Humanidades fue creada el 11 de febrero de 1943 mediante el Decreto de Ley Nº10.358 con los cometidos de:

Si bien el proyecto aprobado nunca se  logró concretar, el 9 de octubre de 1946 fue aprobada una nueva ley, la Ley N.º 10.658 donde se modificaron los cometidos del Decreto de Ley de 1943 y se creó la Facultad de Humanidades y Ciencias.
La cual abrió sus puertas ese mismo año, en el entonces edificio del Hotel Nacional en la Ciudad Vieja de Montevideo, sobre calle Juan Lindolfo Cuestas. Edificio que hoy en día es monumento histórico.

En 1987 la Facultad de Humanidades y Ciencias fue disuelta y se crearon dos nuevas facultades dentro de la Universidad de la República: primero fue creada la Facultad de Humanidades y Ciencias de la Educación, enfocada en el estudio y en las licenciaturas de historia, filosofía, lingüística, letras, antropología, ciencias de la educación, y turismo (binacional); y por otro lugar fue creada la Facultad de Ciencias, enfocada en estudiar las licenciaturas de biología, bioquímica, geografía, geología, física y matemática.

Posteriormente la nueva facultad de Humanidades y Ciencias de la Educación, se mudaria hacia su sede actual, en el que fuera edificio de la Scuola Italiana de Montevideo, en el barrio del Cordón, sobre la calle Magallanes.

Títulos de grado y posgrado
La Facultad otorga los siguientes títulos de grado:
 Licenciado en Historia
 Licenciado en Filosofía
 Licenciado en Lingüística
 Licenciado en Letras
 Licenciado en Ciencias Antropológicas
 Licenciado en Educación
 Licenciado en Turismo (se dicta en Maldonado y de carácter binacional en Salto)
Licenciado en Biología Humana (carrera compartida)
 Técnico Universitario en Corrección de Estilo (Lengua española)
Técnico en Interpretación y Traducción Lengua de Señas Uruguaya - Español
Tecnicatura Universitaria en Bienes Culturales (mención en Historia Regional y Local y mención en Patrimonio)
Tecnicatura Universitaria en Dramaturgia

También otorga títulos de posgrado en la Maestría en Ciencias Humanas que cuenta con diversas opciones: Literatura Latinoamericana, Lenguaje, Cultura y Sociedad, Filosofía Contemporánea, Teatro, Historia Rioplatense, Antropología, Estudios Latinoamericanos y Docencia Universitaria. En 2014 se iniciaron los estudios de doctorado en las mismas opciones.

Estudiantes

En 2012 los estudiantes estaban distribuidos de la siguiente manera: 94 en la Licenciatura Binacional en Turismo, 922 en la Licenciatura en Ciencias Antropológicas, 819 en la Licenciatura en Ciencias de la Educación, 816 en la Licenciatura en Ciencias Históricas, 735 en la LIcenciatura en Filosofía, 871 en la Licenciatura en Letras, 503 en la Licenciatura en Lingüística, 145 en la Licenciatura en Turismo, 556 en la Tecnicatura Universitaria en Corrección de Estilo, 24 en la Tecnicatura Universitaria en Interpretación LSU Español LSU, 477 en la Tecnicatura Universitaria en Museología, 15 en la Tecnicatura Universitaria en Turismo.

Biblioteca
Para estudiantes, docentes y egresados la facultad cuenta con una biblioteca de importante caudal y materiales de acervo bibliográfico destacado. 1994 es el año en que se digitalizó el proceso de búsqueda de libros. Las publicaciones de docentes de la facultad pueden encontrarse en esta base de datos, aunque en la misma permanecen los ficheros manuales con publicaciones posteriores. También cuenta en su sala con diez computadoras de consulta con acceso a Internet. En la biblioteca se puede solicitar el carné interbibliotecario, que permite acceder a las bibliotecas de otras facultades de la UdelaR.

Idiomas
Los estudiantes de la UdelaR pueden aprender en esta facultad diferentes idiomas, como alemán, francés, inglés, italiano y portugués. También pueden tomar cursos de lenguas, como catalán, gallego, griego, latín, griego moderno, cultura y taller de italiano, portugués, japonés y vasco. Además de la lengua de señas.

Departamentos de Facultad de Humanidades y Ciencias de la Educación

Decanos
El director, desde su fundación, fue luego el primer decano, Carlos Vaz Ferreira. Designado por ley, la formación de esta facultad había sido uno de los grandes empeños de su vida por décadas. Le siguieron Justino Jiménez de Aréchaga, Fructuoso Pittaluga, Emilio Oribe (como decano interino), por dos períodos consecutivos cumpliendo su tercer decanato Carlos Vaz Ferreira. Luego Emilio Oribe, Rodolfo Tálice siendo el segundo con dos períodos consecutivos en el decanato, Arturo Ardao y Mario H. Otero.

Durante la dictadura cívico-militar (1973 - 1985), los decanos de esta facultad fueron designados directamente por el régimen de facto. Los interventores fueron Miguel Ángel Klappenbach y Rodolfo Gori Carrara.

Luego del retorno a la democracia, los decanos fueron Mario H. Otero, Carlos Zubillaga, Adolfo Elizaincín, José Seoane y  Álvaro Rico. En 2018 La Asamblea del Claustro de la Facultad de Humanidades y Ciencias de la Educación (FHCE) eligió a la historiadora Ana Frega como decana por el período 2018-2022 siendo la primera mujer en ocupar dicho cargo en la Historia de la Facultad

Profesores honoríficos
Reconocimiento de la Facultad de Humanidades y Ciencias de la Educación

Notas

Referencias

Enlaces externos
 Página oficial de la Facultad de Humanidades y Ciencias de la Educación.
 Página oficial del Centro de Estudiantes de Humanidades y Ciencias de la Educación (CEHCE-ASCEEP-FEUU)

Facultades de la Universidad de la República
Facultades de Humanidades
Cordón (Montevideo)

redpajama_set_name: RedPajamaWikipedia


text:
Juan Cruz Azpíroz Goicoechea, más conocido en su época como Chiquito de Arruiz (ahora, Txikito de Arruitz), (Arruiz, 1929 - 2 de junio de 1996) fue un deportista español, un korrikolari (en euskera, corredor), exponente de una atlética modalidad de deporte vasco cuyas condiciones de práctica «difícilmente comparables a las carreras olímpicas perfectamente reglamentadas». Es una modalidad donde se llega a mezclar, en muchas ocasiones, más de una práctica: korrikolari y aizkolari.

Biografía
Nacido en Arruiz, en el Valle de Larraún, fue un deportista que, según las crónicas de la época, presentaba una cualidades singulares. Se tiene noticia de que, en 1956, fue examinado por el doctor Hans Reindell, cardiólogo, y Waldemar Gerschler, entrenador de atletismo y profesor de la Universidad de Friburgo, que habían desarrollado un método de entrenamiento atlético. Según cuentan, quedaron asombrados de los resultados arrojados en las pruebas que le realizaron.

Entre otros desafíos contra competidores locales, donde suelen mediar apuestas, se tiene noticia de dos retos más singulares e internacionales:

 El 29 de octubre de 1961 el navarro Juan Cruz Azpiroz y el guipuzcoano Miguel Aldaz, también korrikolari, en una apuesta realizada en la plaza de toros de El Chofre, en San Sebastián, retaron al británico Gordon Pirie, antiguo plusmarquista mundial en 3.000 y 5.000 metros. La prueba era sobre un recorrido de 10.000 donde el navarro y el guipuzcoano corrieron cada uno cinco mil metros mientras que el inglés hizo el recorrido completo, sumando un total de 100 vueltas. La victoria fue para la pareja de deportistas vascos.
 En 1963 logró otra gesta «cuando cortó veinte troncos de 54 pulgadas y corrió después 20 kilómetros en 2:38:36.»

Estuvo casado con Maritxu Bengoechea.

Premios y reconocimientos

 12 de octubre de 1997. Homenaje del Ayuntamiento de Lecumberri.
 Memorial Txikito de Arruitz. Con más de treinta ediciones, se celebra en Lecumberri en recuerdo de este deportista.

Véase también

 Deporte rural vasco

Referencias

Bibliografía

Enlaces externos


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Medical Malpractice Lawyers Attorneys does not provide attorneys for all locations. We reserve the right to dercline case referrals or responses without notification.


The CET invests in educational research, initiatives, interventions and projects that address inequalities in learning outcomes and increase teacher effectiveness.
Learning outcomes are both the social and the cognitive skills and capabilities valued in our society.
The definition of "teacher" embraces a broad range of people who impact on a student's learning outcomes and includes: members of the teaching profession, related professions, support staff; parents, family and whanau and the wider community.
Increasing teacher effectiveness, because the evidence shows that effectiveness in teaching is the single most powerful influence on learning outcomes.
Seek to work collectively and in collaboration with other funders and will support purposeful collaboration between schools and other interested stakeholders.
CET has recently formed a 3 year funding partnership with The Education Hub and will contribute to the funding of the Bright Spots awards.


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text:
Glasgow Prog Rockers ATLAS : EMPIRE Track Premiere "As Yet Unwritten" via RebelNoise
· Atlas : Empire · Music News
Montreal, QC – November 5, 2018
For fans of Thrice, Circa Survive, Glassjaw, At The Drive-In
New Album "The Stratosphere Beneath Our Feet" Out December 7th
Music Video "Hostess"
L-R – Robert Hasebe (Bassist), Jamie Sturt (Guitar and Vocals), Steven Gillies (Guitar and Vocals)
Glasgow's ATLAS : EMPIRE will be releasing their new album "The Stratosphere Beneath Our Feet" on December 7th, 2018. Weaving their way between the multitudes of different genres that influence them, the trio visit the worlds of heavy progressive rock and expansive ambient shoegaze. Having already shared two music videos "Hostess" and "Gethsemane" in support of the upcoming release, the band is premiering the album's opener "As Yet Unwritten" on RebelNoise.com at the following link: http://www.rebelnoise.com/articles/song-premiere-as-yet-unwritten-by-atlas-empire.
Guitarist Steven Gillies comments:
"As Yet Unwritten" is one of the most uplifting songs on the album – from the major key arpeggios in the verse, via the fuzzy 5/4 lead riff to a massive chorus. Lyrically, it deals with insights of a possible future and the different stages of acceptance & adaptation to "the end of the world".
Since forming in 2011, ATLAS : EMPIRE have enjoyed success both through their recordings and several tours crossing the UK, the EU and Eastern Canada, including performing at Indieweek in Toronto.
To date the band has released 3 EPs, "To The Astronaut…" (2012); "Somnus" (2013) and "For the Satellites" (2015) with "The Stratosphere Beneath Our Feet" as their 2018 debut full length.
An ambitious album, the band is eager to get "The Stratosphere Beneath Our Feet" into the ears of their fans.
Gillies adds:
"The Stratosphere Beneath Our Feet" is a concept album, based around humanity's growing reliance on technology and specifically how society falls apart when that fails us. We wrote each song like a chapter in a book, both musically and lyrically, to follow that narrative."
"The Stratosphere Beneath Our Feet" is available for pre-order at the following link: https://atlasempire.bandcamp.com.
Music Video – "Gethsemane" – https://youtu.be/qQTZKa49OLo
Music Video – "Hostess" – https://youtu.be/SYkm0vN79eE
1. As Yet Unwritten
2. Diminishing Returns
3. It's All In The Reflexes
4. The Moment We Were Exploding
5. Gethsemane
6. The Entire of History You
7. Hostess
8. The Year of The Four Emperors
9. Our Hands Part The Waves
10. Cenotaphs
Album Band Line Up:
Steven Gillies
Jamie Sturt
Robert Hasebe
Ben Montgomery
https://atlasempire.co.uk
https://facebook.com/atlasempire
https://twitter.com/atlasempireUK
https://www.instagram.com/atlas_empire
"A lesson in progressive rock" – Rocksound (UK)
"The band show an impressive versatility throughout the record as they straddle various genres with ease. Post-hardcore sits neatly alongside the Maybeshewill inspired post-rock…" – abadgeoffriendship.com
"They hit you with a wall of sound, that has a slightly Math feel to it. The tracks have a lot of overlapping phrases, but with darker tones to the guitars, it almost feels like Deftones and Arcane Roots had a lovechild and raised it in 'Bonnie'. Both vocalists lighten the mood and play upon a subtle gaelic charm in between tracks…There's just the right level of melody combined with guitar-wrecking aggression for them to stand out in the Glasgow scene." – threesongsandout.com
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At The Drive-In Glasgow Prog Rockers ATLAS : EMPIRE Track Premiere "As Yet Unwritten" via RebelNoise New Album "The Stratosphere Beneath Our Feet" Out December 7th Music Video "Hostess" circa survive Glassjaw Thrice


In his essay on closing hymns, Rabbi Richard Sarason enumerates the Maimonidean Thirteen Principles of Faith as rendered in Yigdal Elohim Chai ("May the living God be exalted"), the poem attributed to Daniel b. Judah. Has so much theology ever been compressed into so few words? This is a didactic text, filled with cognitive language. How then are we to feel about this eternal, incorporeal, singular, omniscient and just God who has created all things, and who has invested the people of Israel with a prophetic vision, transmitted by Moses through the Torah as an immutable revelation, and in whom we find hope for ultimate redemption and eternal life? With what qualities of expression do we interpret these words through music?
A careful reading of the text suggests many expressive pathways. Exaltation, praise, limitlessness, holiness, majesty, trustworthiness and spiritual intimacy are all valid possibilities. Music for Yigdal, in spite of the textual density of the poem, tends to distill its feeling content into a single melodic strand that is repeated for each strophe, often in a form intended to be sung by all. These melodies may convey one or more of the above qualities, or they may extend our understanding of Yigdal into an emotional-spiritual province not specifically referenced in the poem, as we shall hear. As you listen to the musical examples, consider which feeling-connotations come up for you in each case.
Among American Reform Jews, the most familiar Yigdal may be the one many of us grew up hearing in English as "We Praise the Living God." The melody is ascribed to Meyer Lyon (Leoni), an 18th-century cantor in London. It was adopted for use in the Methodist church as "The God of Abraham Praise," and many Christian hymnals still include a variant with Leoni's name attached. We listen to it now in Hebrew, as recorded for the Transcontinental Music compact disc compilation, "Yamim Noraim: Days of Awe," Listen with an accompaniment by Herbert Fromm. This setting seems to evoke the more stately qualities of the poem.
For a traditional cantorial interpretation of Yigdal, let's listen to this vintage recording (1909) by Cantor Zavel Kwartin. Listen It begins with the words "Shefa n'vuato n'tano" ("God inspired with the gift of prophecy") and suggests the sanctity of our human capacity to receive the gift of divine insight. Fair-use standards limit this excerpt to one minute's length, but it's worth tracking down a complete recording online, just to hear the sublime passage that immediately follows, " Torat emet natan l'amo Eil" ("A Torah of truth did God give our people").
The great tenor Richard Tucker can be heard in a Yigdal by Sholom Secunda on the album "Welcoming the Sabbath." Listen In Secunda's music, the soaring and exuberant solo line alternates with a choral-congregational response in which everyone could join.
The call-and-response form takes on a decidedly different garb in this recording of a Sephardic melody by the Israeli artist Yasmin Levy, found on her recent album, Sentir. Listen Levy imparts an almost mystical intimacy to her interpretation. A men's ensemble chimes in periodically with repetitions of the closing melodic phrase.
The renowned conductor-composer Leonard Bernstein contributed to the Yigdal literature with a simple round, published in The Songs We Sing (1950), a well-known anthology of the era. It is given a spirited performance by the Rochester Singers, conducted by Samuel Adler, on Leonard Bernstein: A Jewish Legacy, issued by the Milken Archive of Jewish Music . Listen The contagious joyfulness of this rendition evokes a sense of celebration arising not specifically from the poem, but rather from our response to it: how delightful it is to live in the light of an all-encompassing God.
Finally, here's another Sephardic melody, arranged and performed by Danny Maseng and collaborators on his disc, Labor of Love. Listen Danny Maseng says, "it is bursting with joy and energy," and this setting definitely coaxes us out of our seats. "May the living God be exalted" indeed!
Cantor Richard Cohn serves Temple Emanu-El of Dallas, Texas. He is a past-president of the American Conference of Cantors, as well as the 2009 recipient of the Shomeir Shira award from the Guild of Temple Musicians.


This article examines the intra-city distribution of women's nutritional status across eight Indian mega-cities with a specific focus on slum-non-slum divide. The analysis is based on the National Family Health Survey (2005-06) of India and highlights the dual burden of malnutrition among urban women. The results show that one in every two women in mega-cities is malnourished (either undernourished or over nourished), but a biased, analytical focus on citywide averages conceals the nature of the problem. Over nutrition among women is notably higher in non-slum areas whereas underweight persists as a key concern among slum dwellers. Cities located in the Central India (Nagpur and Indore) have the highest proportion of underweight women whereas the cities in South India (Chennai and Hyderabad) show a high prevalence of overweight women across both slum and non-slum areas. The intensity of income-related inequalities in underweight outcome is much greater for non-slum areas, whereas inequalities in overweight outcomes are higher among slums. Furthermore, regression analysis indicates that place of residence as such has no significant impact on women's nutritional status and that this elementary association is primarily a ramification mediated through other key socioeconomic correlates. Results suggest that, it would be rational to develop a comprehensive urban nutritional plan that focuses on dietary planning and behaviour change to address both type of malnutrition at the same time.


Get Both Nocturnes and Requiems, A Prelude To Sorrow and A WItherfall Ghost Faces Tour Shirt for one low price! Tour dates are on the back and include 70000 Tons and Japanese Dates!
Jake Dreyer, Anthony Crawford,Joseph Michael guitar/bass pick set.
Based out of Los Angeles, Calif., WITHERFALL is the collective brainchild of guitarist Jake Dreyer (Iced Earth, Kobra And The Lotus, White Wizzard), singer Joseph Michael (White Wizzard) and the late Adam Sagan ( Circle II Circle, Into Eternity). With Dreyer and Michael having previously worked together in White Wizzard and Sagan collaborating on with Dreyer on the critically acclaimed debut instrumental EP, "In The Shadows of Madness" - which included a featured track for the popular video game franchise, ROCKBAND - the trio combined forces to begin writing for the new project in 2013.
Eager to resonate their ideas, WITHERFALL headed to Phoenix, Ariz. to self produce their debut album, "Nocturnes And Requiems", with engineer Ralph Patlan (Megadeth, Brian "Head" Welch, MSG) in late 2014. The album was then sent on to New York City for mixing and mastering by Chris "Zeuss" Harris (Rob Zombie, Queensrÿche, Hatebreed) at Planet Z. Resulting in eight masterfully executed tracks featuring the group's dynamic blend of darkened melodic and progressive metal, "Nocturnes and Requiems" is scheduled for release on February 10, 2017. Pre-orders are available now at witherfall.com.
"Nocturnes And Requiems" is dedicated to the life of Adam Sagan who passed on December 7, 2016 during the final stages of production. The band collectively commented, "This, as we know, is the last piece of work that Adam contributed and played on. Adams talent, passion and personality is woven throughout every part of this record as he was easily 1/3 of the creative force. "Nocturnes and Requiems" was a name that Adam eerily came up with one evening when we were figuring out album titles would not have sounded the way it does now without his immense contribution on and off the drums. Adam, we love you and it's a tragedy that you were not able to see this release. You will always and forever be a member of Witherfall. Rest In Peace man."
Nocturnes and Requiems artwork on front and W insignia on back.
Black++++ Import Vinyl with CD and Poster Included... Limited Edition very few copies! Please Include Size with message at checkout!
Full Color Vinyl "Nocturnes and Requiems" album cover sticker plus 1 free Jake Dreyer Witherfall Guitar Pick.