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2M1207b - First image of an exoplanet.jpg
European Southern Observatory infrared image of 2M1207 (bluish) and companion planet 2M1207b (reddish), taken in 2004.
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Centaurus
Right ascension 12h 07m 33.47s[1]
Declination −39° 32′ 54.0″[1]
Apparent magnitude (V) 20.15[2]
Spectral type M8p[1]
V−R color index 2.1[2]
R−I color index 2.1[2]
Parallax (π) 19.1 ± 0.4[2] mas
Distance 172 ± 3 ly
(52.75 ± 1.0[3] pc)
Mass ~0.025[3] M
Radius ~0.25[4] R
Luminosity ~0.002[4] L
Temperature 2550 ± 150[4] K
Age 5·106 to 10·106[4] years
Other designations
2MASSW J1207334−393254[1]
Database references

2M1207, 2M1207A or 2MASS J12073346-3932539 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 (fr) 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 Hα 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
b 3–10[6] MJ 40.6 ± 1.3[14]

See also[edit]


  1. ^ a b c d e NAME 2M1207A, entry, SIMBAD. Accessed on line June 15, 2008.
  2. ^ 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. Bibcode2008A&A...477L...1D doi:10.1051/0004-6361:20078886.
  3. ^ a b c d e "The Distance to the 2M1207 System", Eric Mamajek, November 8, 2007. Accessed on line June 15, 2008.
  4. ^ 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. Bibcode2007ApJ...657.1064M doi:10.1086/510877.
  5. ^ 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 (2): L29–L32. arXiv:astro-ph/0409323Freely accessible. Bibcode:2004A&A...425L..29C. doi:10.1051/0004-6361:200400056. 
  6. ^ a b Star: 2M1207, Extrasolar Planets Encyclopaedia. Accessed on line June 15, 2008.
  7. ^ Mamajek (2005). "A Moving Cluster Distance to the Exoplanet 2M1207b in the TW Hydrae Association". The Astrophysical Journal. 634 (2): 1385–1394. arXiv:astro-ph/0507416Freely accessible. Bibcode:2005ApJ...634.1385M. doi:10.1086/468181. 
  8. ^ More Sun-like stars may have planetary systems than currently thought, library, Origins program, NASA. Accessed on line June 16, 2008.
  9. ^ 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. Bibcode2005ApJ...630L..89G doi:10.1086/462414.
  10. ^ 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. Bibcode2006ApJ...639L..79R doi:10.1086/502647.
  11. ^ 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 3-540-20171-8.
  12. ^ Whelan; Ray, T. P.; Randich, S.; Bacciotti, F.; Jayawardhana, R.; Testi, L.; Natta, A.; Mohanty, S.; et al. (April 10, 2007). "Discovery of a Bipolar Outflow from 2MASSW J1207334-393254, a 24 MJup Brown Dwarf". The Astrophysical Journal. 659 (1): L45 – L48. arXiv:astro-ph/0703112Freely accessible. Bibcode:2007ApJ...659L..45W. doi:10.1086/516734. 
  13. ^ Small Stars Create Big Fuss, Ker Than, May 28, 2007, space.com. Accessed on line June 15, 2008.
  14. ^ From estimated distance of 52.75 ± 1.0 parsec and observed angular separation of 769 ± 10 milliarseconds (angular separation from Mohanty 2007, above.)

External links[edit]

Coordinates: Sky map 12h 07m 33.47s, −39° 32′ 54.0″