Ross 154
| Ross 154 | |
|---|---|
| Observational Data | |
| Designation | HIP 92403 |
| Right ascension | 18h 49m 49.36216s[1] |
| Declination | -23° 50′ 10.4291″[1] |
| Constellation | Sagittarius |
| Type of object | Red dwarf |
| Magnitude | Apparent Mag: +10.95 Absolute Mag: +13.59[2] |
| Astrometry | |
| Distance from Earth | 9.68 ly[3] |
| Radial velocity | -10.5±0.1 km/s[1] |
| Proper motion | RA: 637.02 mas/yr[1] Dec.: -191.64 mas/yr[1] |
| Parallax | 336.72±2.03 mas[1] |
Ross 154 is a red dwarf star which is the seventh closest to our Sun. The star is located 9.7 light years away in the constellation of Sagittarius. Because it is a dim, cool red star, it has an apparent magnitude of only 10.95. It is therefore invisible to the unaided eye and requires a 65 mm telescope aperture to be seen. Ross 154 was first discovered in 1925 by Frank Elmore Ross.
Ross 154 is a cool, dim, red dwarf main sequence star of spectral type of M3.5 Ve.[1] The star has some 17 percent of the mass of our Sun, and around 19 to 24 percent of its diameter.[4] Like all class M dwarfs, Ross 154 emits much of its electromagnetic energy in the infrared, with only 5/10,000th of our Sun's visual luminosity.
Ross 154 is a fast rotating star, indicating that it may be less than a billion years in age.[5] The star also has a low velocity relative to the Sun, further showing that it is likely a Population I star.[6] The star only contains around 56 percent of the metallicity of our Sun, based on its abundance of iron.[7] Ross 154 is also a flare star, and will increase its output of x-rays greatly during a flare. As such, the star is often observed using various X-ray observatories such as the Chandra observatory.
There are no known substellar companions around Ross 154. For an Earth-like planet to have liquid water on its surface, such a world would need to be in a close orbit, centered around 0.19 AU if one accounts for the large amount of infrared radiation from Ross 154. Such a world would orbit Ross 154 in 73 days and would be tidally locked to the star.[8] Because Ross 154 is a flare star known for extreme increases in x-rays during flares, it would be unlikely for life as we understand it to survive on such a hypothetical world.
Because of the proximity of Ross 154 to our own solar system, the star is a "Tier 1" target star for NASA's future optical Space Interferometry Mission to detect smaller worlds in relative close orbit around stars. The ESA's future Darwin mission will serve a similar purpose.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Ross 154 from the SIMBAD Astronomical Database
- ↑ From definition of absolute magnitude, using apparent magnitude (+10.95) and distance (9.68 ly) given here.
- ↑ Calculated from given parallax of 336.72 mas.
- ↑ Johnson, H. and Wright, C. (1983). Predicted infrared brightness of stars within 25 parsecs of the sun. The Astrophysical Journal Supplement Series, 53, p.643. Bibcode:1983ApJS...53..643J
- ↑ Wargelin, B., Kashyap, V., Drake, J., García-Alvarez, D. and Ratzlaff, P. (2008). X-Ray Flaring on the dMe Star, Ross 154. The Astrophysical Journal, 676(1), pp.610-627. arXiv:0712.2791
- ↑ Veeder, G. (1974). Old disk flare stars. The Astronomical Journal, 79, p.702. Bibcode:1974AJ.....79..702V
- ↑ Eggen, O. (1996). Distribution and Corrlation of Age, Abundance, and Motion of Lower Main Sequence Stars. The Astronomical Journal, 111, p.466. Bibcode:1996AJ....111..466E
- ↑ arXiv:astro-ph/0504497