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2M1207, 2M1207A or 2MASSW J1207334-393254 is a brown dwarf located in the constellation Centaurus; a companion object, 2M1207b, may be the first extrasolar planetary mass companion to be directly imaged, and is the first discovered orbiting a brown dwarf.[4][5]
2M1207 was discovered during the course of the 2MASS infrared sky survey: hence the "2M" in its name, followed by its celestial coordinates. With a fairly early (for a brown dwarf) spectral type of M8,[1] it is very young, and probably a member of the TW Hydrae association. Its estimated mass is around 25 Jupiter masses.[3] The companion, 2M1207b, is estimated to have a mass of 3-10 Jupiter masses.[6] Still glowing red hot, it will shrink to a size slightly smaller than Jupiter as it cools over the next few billion years.
An initial photometric estimate for the distance to 2M1207 was 70 parsecs.[3] In December 2005, American astronomer Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the moving cluster method.[7] The new distance gives a fainter luminosity for 2M1207. Recent trigonometric parallax results have confirmed this moving cluster distance, leading to a distance estimate of 53 ± 1 parsec or 172 ± 3 light years.[3]
Like classical T Tauri stars, many brown dwarfs are surrounded by disks of gas and dust which accrete onto the brown dwarf.[8][9] 2M1207 was first suspected to have such a disk because of its broad H- line. This was later confirmed by ultraviolet spectroscopy.[9] The existence of a dust disk has also been confirmed by infrared observations.[10] In general, accretion from disks is known to produce fast-moving jets, perpendicular to the disk, of ejected material.[11] This has also been observed for 2M1207; an April 2007 paper in the Astrophysical Journal reports that this brown dwarf is spouting jets of material from its poles.[12] The jets, which extend around 109 kilometers into space, were discovered using the Very Large Telescope (VLT) at the European Southern Observatory. Material in the jets streams into space at a few kilometers per second.[13]
The 2M1207 system
| Companion |
Mass |
Observed separation
(AU) |
| b |
3-10[6] MJ |
40.6 ± 1.3[14] |
References
- ^ a b c d e NAME 2M1207A, entry, SIMBAD. Accessed on line June 15, 2008.
- ^ a b c d An accurate distance to 2M1207Ab, C. Ducourant, R. Teixeira, G. Chauvin, G. Daigne, J.-F. Le Campion, Inseok Song, and B. Zuckerman, Astronomy and Astrophysics 477, #1 (January 2008), pp. L1-L4. Bibcode: 2008A&A...477L...1D doi:10.1051/0004-6361:20078886.
- ^ a b c d e "The Distance to the 2M1207 System", Eric Mamajek, November 8, 2007. Accessed on line June 15, 2008.
- ^ a b c d e The Planetary Mass Companion 2MASS 1207-3932B: Temperature, Mass, and Evidence for an Edge-on Disk, Subhanjoy Mohanty, Ray Jayawardhana, Nuria Huelamo, and Eric Mamajek, Astrophysical Journal 657, #2 (March 2007), pp. 1064-1091. Bibcode: 2007ApJ...657.1064M doi:10.1086/510877.
- ^ Chauvin, G.; Lagrange, A.-M.; Dumas, C.; Zuckerman, B.; Mouillet, D.; Song, I.; Beuzit, J.-L.; Lowrance, P. (2004). "A Giant Planet Candidate near a Young Brown Dwarf". Astron. Astrophys. 425: L29-L32, http://arxiv.org/abs/astro-ph/0409323v1. Retrieved on 16 November 2008.
- ^ a b Star: 2M1207, Extrasolar Planets Encyclopaedia. Accessed on line June 15, 2008.
- ^ Mamajek (2005). "A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association". The Astrophysical Journal 634: 1385-1394. doi:10.1086/468181, http://adsabs.harvard.edu/abs/2005ApJ...634.1385M.
- ^ More Sun-like stars may have planetary systems than currently thought, library, Origins program, NASA. Accessed on line June 16, 2008.
- ^ a b First Ultraviolet Spectrum of a Brown Dwarf: Evidence for H2 Fluorescence and Accretion, John E. Gizis, Harry L. Shipman, and James A. Harvin, Astrophysical Journal 630, #1 (September 2005), pp. L89-L91. Bibcode: 2005ApJ...630L..89G doi:10.1086/462414.
- ^ Spitzer Observations of Two TW Hydrae Association Brown Dwarfs, Basmah Riaz, John E. Gizis, and Abraham Hmiel, Astrophysical Journal 639, #2 (March 2006), pp. L79-L82. Bibcode: 2006ApJ...639L..79R doi:10.1086/502647.
- ^ Accretion-ejection models of astrophysical jets, R. E. Pudritz, in Accretion Disks, Jets and High-energy Phenomena in Astrophysics, Vassily Beskin, Gilles Henri, Francois Menard, Guy Pelletier, and Jean Dalibard, eds., NATO Advanced Study Institute, Les Houches, session LXXVIII, EDP Sciences/Springer, 2003. ISBN 3540201718.
- ^ Whelan et al. (April 10, 2007). "Discovery of a Bipolar Outflow from 2MASSW J1207334-393254, a 24 MJup Brown Dwarf". The Astrophysical Journal 659: L45 - L48. doi:10.1086/516734. Bibcode: 2007ApJ...659L..45W.
- ^ Small Stars Create Big Fuss, Ker Than, May 28, 2007, space.com. Accessed on line June 15, 2008.
- ^ From estimated distance of 52.75 ± 1.0 parsec and observed angular separation of 769 ± 10 milliarseconds (angular separation from Mohanty 2007, above.)
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