Published Article: UGPS J194310+183851: an unusual optical and X-ray faint cataclysmic variable?
Title: UGPS J194310+183851: an unusual optical and X-ray faint cataclysmic variable?
The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near-infrared filters in the UKIDSS Galactic Plane Survey (UGPS) allows for the discovery of variability on the time-scale of minutes. We report on the nature of one such object, through the use of optical spectroscopy, time series photometry, and targeted X-ray observations. We propose that UGPS J194310.32+183851.8 is a magnetic cataclysmic variable star of novel character, probably featuring a longer than average spin period and an orbital period likely to be shorter than the period gap (i.e. Porb < 2 h). We reason that the star is likely a member of the short-period intermediate-polar subclass that exists below this period boundary, but with the additional feature that system's spectral energy distribution is fainter and redder than other members of the group.
Morris, C.; Maccarone, T. J.; Lucas, P. W.; Strader, J.; Britt, C. T.; Miller, N.; Swihart, S. J.; Cooper, W. J.; Drew, J. E.; Guo, Z.
Monthly Notices of the Royal Astronomical Society
Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1
https://doi.org/10.1093/mnras/stac2595
Moór, Attila ; Ábrahám, Péter ; Kóspál, Ágnes ; Su, Kate Y. L. ; Rieke, George H. ; Vida, Krisztián ; Cataldi, Gianni ; Bódi, Attila ; Bognár, Zsófia ; Cseh, Borbála ; et al ( September 2022 , Monthly Notices of the Royal Astronomical Society)
Extreme debris discs are characterized by unusually strong mid-infrared excess emission, which often proves to be variable. The warm dust in these discs is of transient nature and is likely related to a recent giant collision occurring close to the star in the terrestrial region. Here we present the results of a 877 d long, gap-free photometric monitoring performed by the Spitzer Space Telescope of the recently discovered extreme debris disc around TYC 4209-1322-1. By combining these observations with other time-domain optical and mid-infrared data, we explore the disc variability of the last four decades with particular emphasis on the last 12 yr. During the latter interval the disc showed substantial changes, the most significant was the brightening and subsequent fading between 2014 and 2018 as outlined in WISE data. The Spitzer light curves outline the fading phase and a subsequent new brightening of the disc after 2018, revealing an additional flux modulation with a period of ∼39 d on top of the long-term trend. We found that all these variations can be interpreted as the outcome of a giant collision that happened at an orbital radius of ∼0.3 au sometime in 2014. Our analysis implies that a collision on a similar scale couldmore »have taken place around 2010, too. The fact that the disc was already peculiarly dust rich 40 yr ago, as implied by IRAS data, suggests that these dust production events belong to a chain of large impacts triggered by an earlier even more catastrophic collision.
SN 2020acat: an energetic fast rising Type IIb supernova
Medler, K. ; Mazzali, P. A. ; Teffs, J. ; Ashall, C. ; Anderson, J. P. ; Arcavi, I. ; Benetti, S. ; Bostroem, K. A. ; Burke, J. ; Cai, Y-Z ; et al ( May 2022 , Monthly Notices of the Royal Astronomical Society)
The ultraviolet (UV) and near-infrared (NIR) photometric and optical spectroscopic observations of SN 2020acat covering ∼250 d after explosion are presented here. Using the fast rising photometric observations, spanning from the UV to NIR wavelengths, a pseudo-bolometric light curve was constructed and compared to several other well-observed Type IIb supernovae (SNe IIb). SN 2020acat displayed a very short rise time reaching a peak luminosity of $\mathrm{{\rm Log}_{10}}(L) = 42.49 \pm 0.17 \, \mathrm{erg \, s^{-1}}$ in only ∼14.6 ± 0.3 d. From modelling of the pseudo-bolometric light curve, we estimated a total mass of 56Ni synthesized by SN 2020acat of MNi = 0.13 ± 0.03 M⊙, with an ejecta mass of Mej = 2.3 ± 0.4 M⊙ and a kinetic energy of Ek = 1.2 ± 0.3 × 1051 erg. The optical spectra of SN 2020acat display hydrogen signatures well into the transitional period (≳ 100 d), between the photospheric and the nebular phases. The spectra also display a strong feature around 4900 Å that cannot be solely accounted for by the presence of the Fe ii 5018 line. We suggest that the Fe ii feature was augmented by He i 5016 and possibly by the presence of N ii 5005. From both photometric and spectroscopic analysis, we inferred that the progenitor of SN 2020acat was an intermediate-mass compact star with an MZAMS of 15–20 M⊙.
Optimizing Cadences with Realistic Light-curve Filtering for Serendipitous Kilonova Discovery with Vera Rubin Observatory
https://doi.org/10.3847/1538-4365/ac3bae
Andreoni, Igor ; Coughlin, Michael W. ; Almualla, Mouza ; Bellm, Eric C. ; Bianco, Federica B. ; Bulla, Mattia ; Cucchiara, Antonino ; Dietrich, Tim ; Goobar, Ariel ; Kool, Erik C. ; et al ( December 2021 , The Astrophysical Journal Supplement Series)
Current and future optical and near-infrared wide-field surveys have the potential to find kilonovae, the optical and infrared counterparts to neutron star mergers, independently of gravitational-wave or high-energy gamma-ray burst triggers. The ability to discover fast and faint transients such as kilonovae largely depends on the area observed, the depth of those observations, the number of revisits per field in a given time frame, and the filters adopted by the survey; it also depends on the ability to perform rapid follow-up observations to confirm the nature of the transients. In this work, we assess kilonova detectability in existing simulations of the Legacy Survey of Space and Time strategy for the Vera C. Rubin Wide Fast Deep survey, with focus on comparing rolling to baseline cadences. Although currently available cadences can enable the detection of >300 kilonovae out to ∼1400 Mpc over the 10 year survey, we can expect only 3–32 kilonovae similar to GW170817 to be recognizable as fast-evolving transients. We also explore the detectability of kilonovae over the plausible parameter space, focusing on viewing angle and ejecta masses. We find that observations in redderizybands are crucial for identification of nearby (within 300 Mpc) kilonovae that could be spectroscopicallymore »classified more easily than more distant sources. Rubin's potential for serendipitous kilonova discovery could be increased by gain of efficiency with the employment of individual 30 s exposures (as opposed to 2 × 15 s snap pairs), with the addition of red-band observations coupled with same-night observations ingorrbands, and possibly with further development of a new rolling-cadence strategy.
Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System
https://doi.org/10.3847/1538-4357/ac3a72
Otani, T. ; Lynas-Gray, A. E. ; Kilkenny, D. ; Koen, C. ; von Hippel, T. ; Uzundag, M. ; Vučković, M. ; Pennock, C. M. ; Silvotti, R. ( February 2022 , The Astrophysical Journal)
AQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. Photometric monitoring of AQ Col reveals a pulsation timing variation with a period of 486 days, interpreted as time delay due to reflex motion in a wide binary formed with an unseen companion with expected mass larger than 1.05M⊙. The optical spectra and color–magnitude diagram of the system suggested that the companion is not a main-sequence star but a white dwarf or neutron star. The pulsation timing variation also shows that the system has an eccentricity of 0.424, which is much larger than any known sdB long period binary system. That might be due to the existence of another short period companion to the sdB star. Two optical spectra obtained on 1996 December 5 show a radial velocity change of 49.1 km s−1in 46.1 minutes, which suggests the hot subdwarf in the wide binary is itself a close binary formed with another unseen white dwarf or neutron star companion; if further observations show this interpretation to be correct, AQ Col is an interesting triple system worthy of further study.
Multiphase outflows in post-starburst E+A galaxies – I. General sample properties and the prevalence of obscured starbursts
https://doi.org/10.1093/mnras/stab3232
Baron, Dalya ; Netzer, Hagai ; Lutz, Dieter ; Prochaska, J. Xavier ; Davies, Ric I. ( November 2021 , Monthly Notices of the Royal Astronomical Society)
E+A galaxies are believed to be a short phase connecting major merger ultraluminous infrared galaxies (ULIRGs) with red and dead elliptical galaxies. Their optical spectrum suggests a massive starburst that was quenched abruptly, and their bulge-dominated morphologies with tidal tails suggest that they are merger remnants. Active galactic nucleus (AGN)-driven winds are believed to be one of the processes responsible for the sudden quenching of star formation and for the expulsion and/or destruction of the remaining molecular gas. Little is known about AGN-driven winds in this short-lived phase. In this paper, we present the first and unique sample of post-starburst galaxy candidates with AGNs that show indications of ionized outflows in their optical emission lines. Using Infrared Astronomical Satellite–far infrared (IRAS–FIR) observations, we study the star formation in these systems and find that many systems selected to have post-starburst signatures in their optical spectrum are in fact obscured starbursts. Using SDSS spectroscopy, we study the stationary and outflowing ionized gas. We also detect neutral gas outflows in 40 per cent of the sources with mass outflow rates 10–100 times more massive than in the ionized phase. The mean mass outflow rate and kinetic power of the ionized outflows in our sample ($\dot{M}\simmore »1\, \mathrm{M_{\odot }\, yr^{-1}}$, $\dot{E}\sim 10^{41}\, \mathrm{erg\, s}^{-1}$) are larger than those derived for active galaxies of similar AGN luminosity and stellar mass. For the neutral outflow ($\dot{M}\sim 10\, \mathrm{M_{\odot }\, yr^{-1}}$, $\dot{E}\sim 10^{42}\, \mathrm{erg\, s}^{-1}$), their mean is smaller than that observed in (U)LIRGs with and without AGN.
Publisher's Version of Record at https://doi.org/10.1093/mnras/stac1718
Morris, C., Maccarone, T. J., Lucas, P. W., Strader, J., Britt, C. T., Miller, N., Swihart, S. J., Cooper, W. J., Drew, J. E., and Guo, Z.. UGPS J194310+183851: an unusual optical and X-ray faint cataclysmic variable?. Monthly Notices of the Royal Astronomical Society 514.4 Web. doi:10.1093/mnras/stac1718.
Morris, C., Maccarone, T. J., Lucas, P. W., Strader, J., Britt, C. T., Miller, N., Swihart, S. J., Cooper, W. J., Drew, J. E., & Guo, Z.. UGPS J194310+183851: an unusual optical and X-ray faint cataclysmic variable?. Monthly Notices of the Royal Astronomical Society, 514 (4). https://doi.org/10.1093/mnras/stac1718
Morris, C., Maccarone, T. J., Lucas, P. W., Strader, J., Britt, C. T., Miller, N., Swihart, S. J., Cooper, W. J., Drew, J. E., and Guo, Z.. "UGPS J194310+183851: an unusual optical and X-ray faint cataclysmic variable?". Monthly Notices of the Royal Astronomical Society 514 (4). Country unknown/Code not available: Oxford University Press. https://doi.org/10.1093/mnras/stac1718. https://par.nsf.gov/biblio/10369045.
place = {Country unknown/Code not available}, title = {UGPS J194310+183851: an unusual optical and X-ray faint cataclysmic variable?}, url = {https://par.nsf.gov/biblio/10369045}, DOI = {10.1093/mnras/stac1718}, abstractNote = {ABSTRACT The growing number of multi-epoch optical and infrared sky surveys are uncovering unprecedented numbers of new variable stars, of an increasing number of types. The short interval between observations in adjacent near-infrared filters in the UKIDSS Galactic Plane Survey (UGPS) allows for the discovery of variability on the time-scale of minutes. We report on the nature of one such object, through the use of optical spectroscopy, time series photometry, and targeted X-ray observations. We propose that UGPS J194310.32+183851.8 is a magnetic cataclysmic variable star of novel character, probably featuring a longer than average spin period and an orbital period likely to be shorter than the period gap (i.e. Porb < 2 h). We reason that the star is likely a member of the short-period intermediate-polar subclass that exists below this period boundary, but with the additional feature that system's spectral energy distribution is fainter and redder than other members of the group.}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {514}, number = {4}, publisher = {Oxford University Press}, author = {Morris, C. and Maccarone, T. J. and Lucas, P. W. and Strader, J. and Britt, C. T. and Miller, N. and Swihart, S. J. and Cooper, W. J. and Drew, J. E. and Guo, Z.}, }