Teegarden's star

Teegarden's Star
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension 02h 53m 00.85s[1]
Declination +16° 52′ 53.3″[1]
Apparent magnitude (V) 15.14[2]
Characteristics
Spectral type M6.5 V[2]
Apparent magnitude (B) ~17.21[1]
Apparent magnitude (V) ~15.40[1]
Apparent magnitude (R) ~14.1[3]
Apparent magnitude (I) ~10.4[3]
Apparent magnitude (J) 8.394 ± 0.027[4]
Apparent magnitude (H) 7.883 ± 0.040[4]
Apparent magnitude (K) 7.585 ± 0.046[4]
Astrometry
Radial velocity (Rv)68.3[5] km/s
Proper motion (μ) RA: +3,386[6] mas/yr
Dec.: –3,747[6] mas/yr
Parallax (π)259.25 ± 0.94[7] mas
Distance12.58 ± 0.05 ly
(3.86 ± 0.01 pc)
Absolute magnitude (MV)17.22[8]
Details
Mass0.08[2] M☉
Radius0.127±0.004[9] R☉
Luminosity0.00073[9] L☉
Temperature2,637[10] K
Metallicity [Fe/H]−0.55[10] dex
Rotational velocity (v sin i)10±4[5] km/s
Other designations
Teegarden's Star, 2MASS J02530084+1652532, APM EO0425-0315372, FBS L 14-17, FBS 0250+167, GAT 1370, LSPM J0253+1652, SO J025300.5+165258, USNO-A2.0 1050-00774305, USNO-B1.0 1068-00028941.[1]
Database references
SIMBADdata
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)
Teegarden's Star (top, center) is the 24th nearest star (system) to the Solar System.

Teegarden's Star (SO J025300.5+165258, 2MASS J02530084+1652532, LSPM J0253+1652) is an M-type red dwarf[2] in the constellation Aries, located about 12 light years from the Solar System. Despite its proximity to Earth it is a dim magnitude 15 and can only be seen through large telescopes. This star was found to have a very large proper motion of about 5 arcseconds per year. Only seven stars with such large proper motions are currently known.[1]

Discovery

Teegarden's Star was discovered in 2003 using asteroid tracking data that had been collected years earlier. This data set is a digital archive created from optical images taken over a 5-year period by the Near Earth Asteroid Tracking (NEAT) program using two 1-m telescopes located on Maui. The star is named after the discovery team leader, Bonnard J. Teegarden, an astrophysicist at NASA's Goddard Space Flight Center.[11]

Astronomers have long thought it was quite likely that many undiscovered dwarf stars exist within 20 light years of Earth, because stellar-population surveys show the count of known nearby dwarf stars to be lower than otherwise expected and these stars are dim and easily overlooked. Teegarden's team thought that these dim stars might be found by data mining some of the huge optical sky survey data sets taken by various programs for other purposes in previous years. So they reexamined the NEAT asteroid tracking data set and found this star. The star was then located on photographic plates from the Palomar Sky Survey taken in 1951. This discovery is significant as the team did not have direct access to any telescopes and did not include professional astronomers at the time of the discovery.[11]

Properties

Teegarden's Star is identified as a red dwarf, but with a mass of 0.08[2] times that of the Sun it is just above the upper limit of objects classified as brown dwarfs. The inherent low temperatures of such objects explain why it was not discovered earlier,[12] since it has an apparent magnitude of only 15.4[2] (and an absolute magnitude of 17.47[8]). Like most red and brown dwarfs it emits most of its energy in the infrared spectrum.[13]

The parallax was initially measured as 0.43 ± 0.13 arcseconds. This would have placed its distance at only 7.50 light years, making Teegarden's Star only the third star system in order of distance from the Sun, ranking between Barnard's Star and Wolf 359.[11] However, even at that time the anomalously low luminosity (the absolute magnitude would have been 18.5) and high uncertainty in the parallax suggested that it was in fact somewhat farther away, still one of the Sun's nearest neighbors but not nearly as high in the ranking in order of distance. A more accurate parallax measurement of 0.2593 arcseconds was made by George Gatewood in 2009, yielding the now accepted distance of 12.578 light years.[7]

Planet searches

Radial velocity measurements have been made by the ROPS survey on two nights in November 2010. The results showed some variation, with increasing radial velocities on the first night and decreasing velocities on the second night, though there is insufficient data to make claims of planet detection.[14]

See also

References

  1. 1 2 3 4 5 6 "2MASS J02530084+1652532 -- Brown Dwarf (M<0.08solMass)". SIMBAD - Centre de Données astronomiques de Strasbourg. Retrieved 2012-01-01.
  2. 1 2 3 4 5 6 The 100 nearest star systems, Research Consortium On Nearby Stars, January 1, 2012, retrieved 2012-03-07. The object is listed as SO 0253+1652.
  3. 1 2 Monet, David G.; et al. (February 2003), "The USNO-B Catalog", The Astronomical Journal 125 (2): 984–993, arXiv:astro-ph/0210694, Bibcode:2003AJ....125..984M, doi:10.1086/345888
  4. 1 2 3 Cutri, R. M.; et al. (June 2003), 2MASS All Sky Catalog of point sources, NASA/IPAC, Bibcode:2003tmc..book.....C
  5. 1 2 Tanner, Angelle; et al. (November 2012), "Keck NIRSPEC Radial Velocity Observations of Late-M Dwarfs", The Astrophysical Journal Supplement 203 (1): 7, arXiv:1209.1772, Bibcode:2012ApJS..203...10T, doi:10.1088/0067-0049/203/1/10, 10.
  6. 1 2 Lépine, Sébastien; Shara, Michael M. (March 2005), "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", The Astronomical Journal 129 (3): 1483–1522, arXiv:astro-ph/0412070, Bibcode:2005AJ....129.1483L, doi:10.1086/427854
  7. 1 2 George Gatewood; et al. (January 2009). "Allegheny Observatory Parallaxes for Late M Dwarfs and White Dwarfs". The Astronomical Journal 137 (1): 402–405. Bibcode:2009AJ....137..402G. doi:10.1088/0004-6256/137/1/402.
  8. 1 2 Henry, Todd J.; et al. (December 2006), "The Solar Neighborhood. XVII. Parallax Results from the CTIOPI 0.9 m Program: 20 New Members of the RECONS 10 Parsec Sample", The Astronomical Journal 132 (6): 2360–2371, arXiv:astro-ph/0608230, Bibcode:2006AJ....132.2360H, doi:10.1086/508233.
  9. 1 2 Dieterich, Sergio B.; Henry, Todd J.; Jao, Wei-Chun; Winters, Jennifer G.; Hosey, Altonio D.; Riedel, Adric R.; Subasavage, John P. (May 2014), "The Solar Neighborhood. XXXII. The Hydrogen Burning Limit", The Astronomical Journal 147 (5): 25, arXiv:1312.1736, Bibcode:2014AJ....147...94D, doi:10.1088/0004-6256/147/5/94, 94.
  10. 1 2 Rojas-Ayala, Bárbara; et al. (April 2012), "Metallicity and Temperature Indicators in M Dwarf K-band Spectra: Testing New and Updated Calibrations with Observations of 133 Solar Neighborhood M Dwarfs", The Astrophysical Journal 748 (2): 32, arXiv:1112.4567, Bibcode:2012ApJ...748...93R, doi:10.1088/0004-637X/748/2/93, 93
  11. 1 2 3 Teegarden, B. J.; et al. (May 20, 2003). "Discovery of a New Nearby Star" (PDF). The Astrophysical Journal Letters 589 (1): L51–L53. arXiv:astro-ph/0302206. Bibcode:2003ApJ...589L..51T. doi:10.1086/375803.
  12. ↑ Reid, Neill I.; Hawley, Suzanne L. (2013), New Light on Dark Stars: Red Dwarfs, Low-Mass Stars, Brown Dwarfs, Springer Praxis Books, p. 342, ISBN 1447136632.
  13. ↑ Kaler, James B. (2011), Stars and Their Spectra: An Introduction to the Spectral Sequence, Cambridge University Press, pp. 126, 132, ISBN 0521899540.
  14. ↑ Barnes J.R.; et al. (July 2012). "ROPS: A New Search for Habitable Earths in the Southern Sky". Monthly Notices of the Royal Astronomical Society 424 (1): 591–604. arXiv:1204.6283. Bibcode:2012MNRAS.424..591B. doi:10.1111/j.1365-2966.2012.21236.x.

External links

This article is issued from Wikipedia - version of the Monday, March 07, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.