Ross 128

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Ross 128
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 11h 47m 44.3964s[1]
Declination +00° 48′ 16″[1]
Apparent magnitude (V) 11.13[2]
Characteristics
Spectral type M4 V[3]
U−B color index 2.685[4]
B−V color index 1.59[5]
Variable type Flare star
Astrometry
Radial velocity (Rv) -31.0[6][7] km/s
Proper motion (μ) RA: 605.66[1] mas/yr
Dec.: -1219.32[1] mas/yr
Parallax (π) 299.59 ± 2.20[1] mas
Distance 10.89 ± 0.08 ly
(3.34 ± 0.02 pc)
Absolute magnitude (MV) 13.51[2]
Details
Mass 0.15[8] M
Radius 0.21[9] R
Luminosity 0.00036[10] L
Luminosity (bolometric) 0.0035[11] L
Surface gravity (log g) 3.40[8] cgs
Temperature 3,180[3] K
Other designations
FI Virginis, FI Vir, G 010-050, GCTP 2730, GJ 447, HIP 57548, LHS 315, Vyssotsky 286, LTT 13240, LFT 852.[1]

Ross 128 is a small star in the equatorial zodiac constellation of Virgo, the virgin. The apparent magnitude of Ross 128 is 11.13,[2] 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.[12]

This low mass star has a stellar classification of M4 V,[3] which places it among a category of stars known as red dwarfs. It has 15%[8] of the mass of the Sun and 21%[9] of the Sun's radius, but generates energy so slowly that it has only 0.036% of the Sun's visible luminosity.[10] 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.[11] This energy is being radiated from the star's outer atmosphere at an effective temperature of 3,180 K.[3] 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.[13] It is classified as an active flare star since it can undergo unpredictable and dramatic increases in luminosity for a period of several minutes.[14] 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.[15]

Distances of the nearest stars from 20,000 years ago until 80,000 years in the future. The approach of Ross 128 is represented by the light salmon-hued line.

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.[16][17] 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.[18][19]

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).[20] 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).[7]

See also[edit]

References[edit]

  1. ^ a b c d e f Perryman, M. A. C. et al. (1997), "The Hipparcos Catalogue", Astronomy & Astrophysics 323: L49–L52, Bibcode:1997A&A...323L..49P 
  2. ^ a b c The One Hundred Nearest Star Systems, Research Consortium on Nearby Stars, 2009-01-01, retrieved 2009-09-03 
  3. ^ a b c d Gautier, Thomas N., III et al., "Far Infrared Properties of M Dwarfs", Bulletin of the American Astronomical Society 36: 1431, Bibcode:2004AAS...205.5503G 
  4. ^ Rufener, F. (October 1976), "Second catalogue of stars measured in the Geneva Observatory photometric system", Astronomy & Astrophysics Supplement Series 26: 275–351, Bibcode:1976A&AS...26..275R 
  5. ^ Warren, W. H., Jr. (1978), "Photoelectric Photometric Catalogue of Homogeneous Means in the UBV System", Observatory (Geneva) 
  6. ^ Gontcharov, G. A. (2006), Pulkovo Compilation of Radial Velocities for 35493 Hipparcos Stars, retrieved 2010-04-18 
  7. ^ a b García-Sánchez, J. et al. (2001), "Stellar encounters with the solar system", Astronomy and Astrophysics 379 (2): 634–659, Bibcode:2001A&A...379..634G, doi:10.1051/0004-6361:20011330 
  8. ^ a b c Rodonò, Marcello, "The Atmospheres of M Dwarfs: Observations", The M-Type Stars, Washington: NASA, pp. 409–453 
  9. ^ a b Kundu, Mukul R. (December 1989), "A VLA survey of nearby flare stars", Astrophysical Journal Supplement Series 71: 895–904, Bibcode:1989ApJS...71..895W, doi:10.1086/191401 
  10. ^ a b Zombeck, Martin V. (2007), Handbook of Space Astronomy and Astrophysics (Third ed.), Cambridge, UK: Cambridge University Press, p. 109, ISBN 0-521-78242-2 
  11. ^ a b "HIP 57548", NASA Exoplanet Archive, retrieved 2012-03-06 
  12. ^ Ross, Frank E. (1926), "New proper-motion stars, (second list)", Astronomical Journal 36 (856): 124–128, Bibcode:1926AJ.....36..124R, doi:10.1086/104699 
  13. ^ Sánchez, F. (1990), Vazquez, M., ed., New windows to the universe 2, Cambridge University Press, p. 313, ISBN 0-521-38429-X 
  14. ^ 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, Bibcode:1975IAUS...67...15K 
  15. ^ Skumanich, Andrew (1986-10-15), "Some evidence on the evolution of the flare mechanism in dwarf stars", Astrophysical Journal, Part 1 309: 858–863, Bibcode:1986ApJ...309..858S, doi:10.1086/164654 
  16. ^ McGuire, Patrick C., Joannah L. et al. (April 2002), "A Near-Infrared, Wide-Field, Proper-Motion Search for Brown Dwarfs", The Astronomical Journal 123 (4): 2027–2032, arXiv:astro-ph/0201140, Bibcode:2002AJ....123.2027H, doi:10.1086/339555 
  17. ^ 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, Bibcode:2000AJ....119..906S, doi:10.1086/301227 
  18. ^ 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, arXiv:astro-ph/0405632, Bibcode:2004ApJS..154..453J, doi:10.1086/422975 
  19. ^ Gautier, Thomas N., III et al. (September 2007), "Far-Infrared Properties of M Dwarfs", The Astrophysical Journal 667 (1): 527–536, arXiv:0707.0464, Bibcode:2007ApJ...667..527G, doi:10.1086/520667 
  20. ^ Allen, C.; Herrera, M. A. (1998), "The galactic orbits of nearby UV Ceti stars", Revista Mexicana de Astronomia y Astrofisica 34: 37–46, Bibcode:1998RMxAA..34...37A 

External links[edit]

Coordinates: Sky map 11h 47m 44.4s, +00° 48′ 16″