Ross 154

Ross 154 (also named V1216 Sgr) is a star in the southern zodiac constellation of Sagittarius. It has an apparent magnitude of 10.44,[Staff] 2008. The one hundred nearest star systems. Research Consortium on Nearby Stars.  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  away from Earth.van Leeuwen F. 2007. Validation of the new Hipparcos reduction. Astronomy and Astrophysics 474 (2): 653–664.  It is the nearest star in the southern constellation Sagittarius, and 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 days. 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 . X-ray flare emission from this star has been observed by Chandra observatory, with a particularly large flare emitting . Wargelin B. J. et al 2008. X-Ray flaring on the dMe Star, Ross 154. The Astrophysical Journal 676 (1): 610–627. 

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 Sun's mass and 24% of the Sun's radius, but it is radiating only 0.38% of the luminosity of the Sun.
This is probably a young star with an age of less than a billion years. The abundance of elements heavier than helium is about half that in the Sun.

 Related pages 
List of nearest stars

 References 

Category:Variable stars
Category:Red dwarfs