Wolf 359

From Wikipedia, the free encyclopedia

Jump to: navigation, search
This article is about the star Wolf 359. For the article about the fictional Star Trek battle, see Battle of Wolf 359.
Wolf 359
Leo constellation map.png
Wolf 359 is shown near the ecliptic in the southern region of Leo. It is invisible to the naked eye.
Observation data
Epoch J2000      Equinox J2000
Constellation Leo
Right ascension 10h 56m 28.99s[1]
Declination +07° 00′ 52.0″[1]
Apparent magnitude (V) 13.54[1]
Characteristics
Spectral type M6.5 Ve[1]
U-B color index +1.54[1]
B-V color index +2.01[1]
Variable type UV[2]
Astrometry
Radial velocity (Rv) +19±1[3] km/s
Proper motion (μ) RA: -3842[1] mas/yr
Dec.: -2725[1] mas/yr
Parallax (π) 419.10 ± 2.10 mas
Distance 7.78 ± 0.04 ly
(2.39 ± 0.01 pc)
Absolute magnitude (MV) 16.64
Details
Mass 0.09[4] M☉
Radius 0.16[5] R☉
Surface gravity (log g) 5.5[6]
Luminosity 0.0009[7] L☉
Temperature 2,800 ± 100[8] K
Rotation <3.0 km/s[3]
Age 1–3.5 × 108[8] years
Other designations
CN Leonis, CN Leo, GJ 406, G 045-020, LTT 12923, LFT 750, LHS 36,[1] GCTP 2553.
Database references
SIMBAD data

Wolf 359 is a small, dim, type M red dwarf star located approximately 7.7 light years from the Earth in the constellation Leo, near the ecliptic. Wolf 359 is a dim magnitude 13.5 and can only be seen with a large telescope. Wolf 359 is one of the nearest stars to the solar system; only the Alpha Centauri system and Barnard's star are known to be closer.

Contents

[edit] Properties

The proper motion of this star was first measured by German astronomer Max Wolf in 1917, using astrophotography. He listed this star as 359.[9] In 1919 he published a catalog of over one thousand high proper motion stars, including this one, that are still identified by his name.[10] The first parallax measurement of Wolf 359 was reported in 1928 from the Mount Wilson Observatory, yielding a value of 0.409 ± 0.009″ and a spectral class of dM4e. It was the lowest mass and faintest star known until the discovery of VB 10 in 1944.[11][12] Its closest neighbor is Ross 128, 1.16 pc or 3.79 ly away.[13]

This is a red dwarf star of spectral class M6.5,[14] although various sources list a spectral class of M5.5,[15] M6[4] or M8.[16] The outer atmosphere of Wolf 359 is sufficiently cool that molecular lines appear in the spectrum, including FeH, CrH, H2O,[17] TiO and possibly CaOH.[18] In 2001 this became the first star other than the Sun to have the spectrum of its corona observed from a ground-based telescope.[19]

The projected rotational velocity of this star's equator is less than 3 km/s; below the threshold of detection through spectral line broadening.[3] This slow rate of rotation is believed to have been caused by loss of angular momentum through a magneto-thermal stellar wind. The time scale for the spin down of a star at spectral class M6 is roughly 10 billion years, because fully-convective stars like this have relatively slow rotation braking.[20] The space velocity of this star suggests that it belongs to the population of old disk stars. However, evolutionary models suggest that it is a relatively young star with an age of less than a billion years.[8]

It is classified as a UV Ceti-type flare star,[2] and has a relatively high flare rate. Its variable star designation is CN Leonis. Observations with the Hubble Space Telescope (HST) detected 32 flare events within a two hour period, with energies of 1027 ergs (1020 joules) and higher.[16] The mean magnetic field has a strength of about 2.2 kG (0.22 tesla), but this varies significantly on time scales as short as six hours.[15] By comparison, the magnetic field of the Sun averages 1 gauss (100 µT), although it can rise as high as 3 kG (0.3 T) in active sunspot regions.[21]

A search of this star by the HST revealed no stellar companions. However this does not preclude the presence of smaller companions that are below the telescope's detection limit (such as a planet in a close orbit), so any planets are likely to be small.[22] No excess infrared emission has been detected, which may indicate the lack of a debris disk in orbit around this star.[23]

[edit] See also

[edit] References

  1. ^ a b c d e f g h i "SIMBAD Query: V* CN Leo -- Flare Star". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=Wolf+359. Retrieved 2007-07-16. 
  2. ^ a b Gershberg, R. E.; Shakhovskaia, N. I. (1983). "Characteristics of activity energetics of he UV Cet-type flare stars". Astrophysics and Space Science 95 (2): 235–253. doi:10.1007/BF00653631. http://adsabs.harvard.edu/abs/1983Ap%26SS..95..235G. Retrieved 2007-07-18. 
  3. ^ a b c Mohanty, Subhanjoy; Basri, Gibor (2003). "Rotation and Activity in Mid-M to L Field Dwarfs". The Astrophysical Journal 583 (1): 451–472. doi:10.1086/345097. http://adsabs.harvard.edu/abs/2002astro.ph..1455M. Retrieved 2007-11-29. 
  4. ^ a b Staff (June 8, 2007). "List of the Nearest 100 Stellar Systems". Research Consortium on Nearby Stars. http://joy.chara.gsu.edu/RECONS/. Retrieved 2007-07-16. 
  5. ^ Doyle, J. G.; Butler, C. J. (1990). "Optical and infrared photometry of dwarf M and K stars". Astronomy and Astrophysics 235 (1-2): 335–339. http://adsabs.harvard.edu/abs/1990A&A...235..335D. Retrieved 2007-07-18. 
  6. ^ Fuhrmeister, B.; Schmitt, J. H. M. M.; Hauschildt, P. H. (September 2005). "PHOENIX model chromospheres of mid- to late-type M dwarfs". Astronomy and Astrophysics 439 (3): 1137–1148. doi:10.1051/0004-6361:20042338. 
  7. ^ West, Frederick R. (2002). "Letter to the Editor: The Corona of CN Leonis (Gliese 406) and its Possible Detection at Radio Frequencies". The Journal of the American Association of Variable Star Observers 30 (2): 149–150. http://adsabs.harvard.edu/abs/2002JAVSO..30..149W. Retrieved 2007-07-18. 
  8. ^ a b c Pavlenko, Ya. V.; Jones, H. R. A.; Lyubchik, Yu.; Tennyson, J.; Pinfield, D. J. (2006). "Spectral energy distribution for GJ406". Astronomy and Astrophysics 447 (2): 709–717. doi:10.1051/0004-6361:20052979. http://adsabs.harvard.edu/abs/2006A&A...447..709P. Retrieved 2007-07-18. 
  9. ^ Wolf, M. (July 1917). "Eigenbewegungssterne". Astronomische Nachrichten 204: 345. Bibcode: 1917AN....204..345W. 
  10. ^ Wolf, M. (1919). "Katalog von 1053 staerker bewegten Fixsternen". Veroeffentlichungen der Badischen Sternwarte zu Heidelberg 7 (10): 195–219. http://articles.adsabs.harvard.edu/abs/1919VeHei...7..195W. Retrieved 2008-07-07.  See p. 206.
  11. ^ van Maanen, Adriaan (1928). "The Photographic Determination of Stellar Parallaxes with the 60- and 100-INCH Reflectors. Fifteenth Series". Contributions from the Mount Wilson Observatory 356: 1–27. Bibcode: 1928CMWCI.356....1V. http://adsabs.harvard.edu/abs/1928CMWCI.356....1V. Retrieved 2009-08-05. 
  12. ^ van Biesbroeck, G. (August 1944). "The star of lowest known luminosity". The Astronomical Journal: 61-62. doi:10.1086/105801. Bibcode: 1944AJ.....51...61V. http://articles.adsabs.harvard.edu/full/seri/AJ.../0051//0000061.000.html?high=49ee8336c004367. 
  13. ^ "Wolf 359". SolStation Company. http://www.solstation.com/stars/wolf359.htm. Retrieved 2006-08-10. 
  14. ^ Mukai, K.; Mason, K. O.; Howell, S. B.; Allington-Smith, J.; Callanan, P. J.; Charles, P. A.; Hassall, B. J. M.; Machin, G.; Naylor, T.; Smale, A. P.; van Paradijs, J. (August 1990). "Spectroscopy of faint, high latitude cataclysmic variable candidates". Monthly Notices of the Royal Astronomical Society 245 (3): 385–391. Bibcode: 1990MNRAS.245..385M. http://adsabs.harvard.edu//abs/1990MNRAS.245..385M. Retrieved 2009-08-06. 
  15. ^ a b Reiners, A.; Schmitt, J. H. M. M.; Liefke, C. (2007). "Rapid magnetic flux variability on the flare star CN Leonis". Astronomy and Astrophysics 466 (2): L13–L16. doi:10.1051/0004-6361:20077095. http://adsabs.harvard.edu/abs/2007A&A...466L..13R. Retrieved 2007-11-26. 
  16. ^ a b Robinson, R. D.; Carpenter, K. G.; Percival, J. W.; Bookbinder, J. A. (1995). "A Search for Microflaring Activity on dMe Flare Stars. I. Observations of the dM8e Star CN Leonis". Astrophysical Journal 451: 795–805. doi:10.1086/176266. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=1995ApJ...451..795R. Retrieved 2007-07-18. 
  17. ^ McLean, Ian S.; McGovern, Mark R.; Burgasser, Adam J.; Kirkpatrick, J. Davy; Prato, L.; Kim, Sungsoo S. (October 2003). "The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low-Resolution Near-Infrared Spectra". The Astrophysical Journal 596 (1): 561–586. doi:10.1086/377636. 
  18. ^ Pesch, Peter (June 1972). "CaOH, a New Triatomic Molecule in Stellar Atmospheres". Astrophysical Journal 174. doi:10.1086/180970. 
  19. ^ Schmitt, J. H. M. M. ; Wichmann, R. (2001). "Ground-based observation of emission lines from the corona of a red-dwarf star". Nature 412 (2): 508–510. doi:10.1038/35087513. http://www.nature.com/nature/journal/v412/n6846/abs/412508a0.html. Retrieved 2007-07-18. 
  20. ^ Röser, Siegfried (2008). Reviews in Modern Astronomy, Cosmic Matter. Wiley-VCH. pp. 49–50, 57. ISBN 3527408207. 
  21. ^ Staff (January 7, 2007). "Calling Dr. Frankenstein! : Interactive Binaries Show Signs of Induced Hyperactivity". National Optical Astronomy Observatory. http://www.noao.edu/outreach/press/pr07/pr0701.html. Retrieved 2006-05-24. 
  22. ^ Daniel J. Schroeder 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. doi:10.1086/301227. http://adsabs.harvard.edu/abs/2000AJ....119..906S. Retrieved 2007-07-18. 
  23. ^ Gautier, T. N.; Beichman, C. A.; Bryden, G.; Chen, C. H.; Gordon, K. D.; Rieke, G. H.; Stansberry, J. A.; Stapelfeldt, K. R.; Trilling, D. E.; Werner, M. W.; MIPS (2004). "Far Infrared Properties of M Dwarfs". Bulletin of the American Astronomical Society 36: 1431-. http://arxiv.org/abs/0707.0464v1. Retrieved 2007-11-29. 

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Wolf_359"