Epoch J2000 Equinox J2000
|Right ascension||11h 47m 44.3964s|
|Declination||+00° 48′ 16″|
|Apparent magnitude (V)||11.13|
|Spectral type||M4 V|
|U−B color index||2.685|
|B−V color index||1.59|
|Variable type||Flare star|
|Radial velocity (Rv)||-31.0 km/s|
|Proper motion (μ)||
RA: 605.66 mas/yr
Dec.: -1219.32 mas/yr
|Parallax (π)||298.2 ± 1.7 mas|
10.94 ± 0.06 ly
(3.35 ± 0.02 pc)
|Absolute magnitude (MV)||13.51|
|Luminosity (bolometric)||0.0035 L☉|
|Surface gravity (log g)||3.40 cgs|
Ross 128 is a small star in the equatorial zodiac constellation of Virgo, the virgin. The apparent magnitude of Ross 128 is 11.13, which is much too faint to be seen with the naked eye. Based upon parallax measurements, the distance of this star from Earth is 10.89 light-years (3.34 parsecs), making it the twelfth closest star to the Solar System. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.
This low mass star has a stellar classification of M4 V, which places it among a category of stars known as red dwarfs. It has 15% of the mass of the Sun and 21% of the Sun's radius, but generates energy so slowly that it has only 0.036% of the Sun's visible luminosity. However, most of the energy being radiated by the star is in the infrared band, with the bolometric luminosity being equal to 0.35% of solar. This energy is being radiated from the star's outer atmosphere at an effective temperature of 3,180 K. This gives it the cool orange-red glow of an M-type star.
Ross 128 is an old disk star, which means it has a low abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, and it orbits near the plane of the Milky Way galaxy. It is classified as an active flare star since it can undergo unpredictable and dramatic increases in luminosity for a period of several minutes. Because of the low rate of flare activity, it is thought to be a magnetically evolved star. That is, there is some evidence that the magnetic braking of the star's stellar wind has lowered the frequency of flares, but not the net yield.
On multiple occasions this star has been examined for the existence of a low stellar mass or brown dwarf companion orbiting at a distance of at least 1 astronomical unit from the primary. However, no companions have yet been discovered. The star also lacks a strong excess of infrared radiation. An infrared excess is usually an indicator of a dust ring in orbit around the star.
Ross 128 is orbiting through the Milky Way with an orbital eccentricity of 0.122, causing its distance from the Galactic Center to range between 26.8–34.2 kly (8.2–10.5 kpc). This orbit will bring the star closer to the Solar System in the future. The nearest approach will occur in about 71,000 years, when it will come within 6.233 ± 0.085 ly (1.911 ± 0.026 pc).
- See also 1
- References 2
- Notes 3
- External links 4
- Perryman, M. A. C.; et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics 323: L49–L52,
- The One Hundred Nearest Star Systems, Research Consortium on Nearby Stars, 2009-01-01, retrieved 2009-09-03
- Gautier, Thomas N., III; et al., "Far Infrared Properties of M Dwarfs", Bulletin of the American Astronomical Society 36: 1431,
- Rufener, F. (October 1976), "Second catalogue of stars measured in the Geneva Observatory photometric system", Astronomy & Astrophysics Supplement Series 26: 275–351,
- Warren, W. H., Jr. (1978), "Photoelectric Photometric Catalogue of Homogeneous Means in the UBV System", Observatory (Geneva)
- Gontcharov, G. A. (2006), Pulkovo Compilation of Radial Velocities for 35493 Hipparcos Stars, retrieved 2010-04-18
- García-Sánchez, J.; et al. (2001), "Stellar encounters with the solar system", Astronomy and Astrophysics 379 (2): 634–659,
- Van Altena W. F., Lee J. T., Hoffleit E. D. (1995). "GCTP 2730". The General Catalogue of Trigonometric Stellar Parallaxes (Fourth ed.). Retrieved 2014-10-20.
- Rodonò, Marcello, "The Atmospheres of M Dwarfs: Observations", The M-Type Stars, Washington: NASA, pp. 409–453
- White, Stephen M.; Jackson, Peter D.; Kundu, Mukul R. (December 1989), "A VLA survey of nearby flare stars", Astrophysical Journal Supplement Series 71: 895–904,
- Zombeck, Martin V. (2007), Handbook of Space Astronomy and Astrophysics (Third ed.), Cambridge, UK: Cambridge University Press, p. 109,
- "HIP 57548", NASA Exoplanet Archive, retrieved 2012-03-06
- Ross, Frank E. (1926), "New proper-motion stars, (second list)", Astronomical Journal 36 (856): 124–128,
- Sánchez, F. (1990), Vazquez, M., ed., New windows to the universe 2, Cambridge University Press, p. 313,
- Kunkel, W. E. (July 29 – August 4, 1974), "Solar neighborhood flare stars - A review", Variable stars and stellar evolution; Proceedings of the Symposium, Moscow, USSR: D. Reidel Publishing Co, pp. 15–46,
- Skumanich, Andrew (1986-10-15), "Some evidence on the evolution of the flare mechanism in dwarf stars", Astrophysical Journal, Part 1 309: 858–863,
- Hinz, Joannah L.; et al. (April 2002), "A Near-Infrared, Wide-Field, Proper-Motion Search for Brown Dwarfs", The Astronomical Journal 123 (4): 2027–2032,
- Schroeder, Daniel J.; et al. (2000), "A Search for Faint Companions to Nearby Stars Using the Wide Field Planetary Camera 2", The Astronomical Journal 119 (2): 906–922,
- Jura, M.; et al. (September 2004), "Mid-Infrared Spectra of Dust Debris around Main-Sequence Stars", The Astrophysical Journal Supplement Series 154 (1): 453–457,
- Gautier, Thomas N., III; et al. (September 2007), "Far-Infrared Properties of M Dwarfs", The Astrophysical Journal 667 (1): 527–536,
- Allen, C.; Herrera, M. A. (1998), "The galactic orbits of nearby UV Ceti stars", Revista Mexicana de Astronomia y Astrofisica 34: 37–46,
- SolStation.com: Ross 128