What is Ross 154?
'''Ross 154''' (also named '''V1216 Sgr''') is a [[star]] in the southern [[zodiac]] [[constellation]] of [[Sagittarius (constellation)|Sagittarius]]. It has an [[apparent magnitude]] of 10.44,<ref name=recon>[Staff] 2008. The one hundred nearest star systems. Research Consortium on Nearby Stars. [http://www.chara.gsu.edu/RECONS/TOP100.posted.htm]</ref> so it is much too faint to be seen with the naked eye. The distance to this star can be estimated from [[parallax]] measurements, which places it at {{Convert|9.69|ly|pc|abbr=off|lk=on}} away from [[Earth]].<ref name=Leeuwen>van Leeuwen F. 2007. Validation of the new Hipparcos reduction. ''Astronomy and Astrophysics'' '''474''' (2): 653–664. [http://www.aanda.org/articles/aa/abs/2007/41/aa8357-07/aa8357-07.html]</ref> It is the nearest star in the southern constellation [[Sagittarius (constellation)|Sagittarius]], and [[List of nearest stars|one of the closest]] to the Sun. This star was first catalogued by American astronomer Frank Elmore Ross in 1925. Ross 154 was found to be a [[UV Ceti]]-type [[flare star]], with a mean time between major flares of about two&nbsp;days.<ref name=recon/> The first such flare activity was observed from Australia in 1951 when the star increased in magnitude by 0.4. Usually, the star will increase by 3–4 magnitudes during a flare. Ross 154 is an [[X-ray]] source and it has been detected by several X-ray observatories. The quiescent X-ray luminosity is about {{nowrap|9 × 10<sup>27</sup> ergs s<sup>−1</sup>}}. X-ray flare emission from this star has been observed by [[Chandra X-ray Observatory|Chandra observatory]], with a particularly large flare emitting {{nowrap|2.3 × 10<sup>33</sup> erg}}.<ref name=warg> Wargelin B. J. ''et al'' 2008. X-Ray flaring on the dMe Star, Ross 154. ''The Astrophysical Journal'' '''676''' (1): 610–627. [http://iopscience.iop.org/0004-637X/676/1/610/]</ref> This is a [[red dwarf]] star that is generating energy through the [[nuclear fusion]] of hydrogen at its core. It has an estimated 17% of the [[so