![]() 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] |
Characteristics | |
Spectral type | M8IVe [1] |
V−R color index | +2.1 [2] |
R−I color index | +2.1 [2] |
Astrometry | |
Proper motion (μ) |
RA: −64.040±0.087
[3]
mas/
yr Dec.: −23.678±0.072 [3] mas/ yr |
Parallax (π) | 15.4624 ± 0.1163 mas [3] |
Distance | 211 ± 2
ly (64.7 ± 0.5 pc) |
Details | |
Mass | ~0.025 [4] M☉ |
Radius | ~0.25 [5] R☉ |
Luminosity | ~0.002 [5] L☉ |
Temperature | 2550 ± 150 [5] K |
Age | 5·106 to 10·106 [5] years |
Other designations | |
2MASSW J1207334−393254, 2MASS J12073346-3932539, TWA 27
[1] | |
Database references | |
SIMBAD | data |
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. [5] [6]
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. [4] The companion, 2M1207b, is estimated to have a mass of 5–6 Jupiter masses. [7] 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. [4] In December 2005, American astronomer Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the moving cluster method. [8] 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. [4]
Like classical T Tauri stars, many brown dwarfs are surrounded by disks of gas and dust which accrete onto the brown dwarf. [9] [10] 2M1207 was first suspected to have such a disk because of its broad Hα line. This was later confirmed by ultraviolet spectroscopy. [10] The existence of a dust disk has also been confirmed by infrared observations [11] and with ALMA. [12] In general, accretion from disks are known to produce fast-moving jets, perpendicular to the disk, of ejected material. [13] 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. [14] 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. [15]
2M1207b shows weak accretion from a disk, inferred from emission lines of hydrogen and helium in medium-resolution NIRSpec data. Surprisingly 2M1207b does not show absorption due to methane, which was predicted to be present for this object. It was suggested that very young objects have a L/T-transition starts at a later spectral type. [16]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( years) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
circumstellar disk | 9.4±1.5 AU | 35+20 −15 ° |
— | |||
b | 5–6 MJ | ≥49.8 ± 1.1 [18] | 633-20046 | 0.02-0.98 | 13-150 ° | — |
![]() 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] |
Characteristics | |
Spectral type | M8IVe [1] |
V−R color index | +2.1 [2] |
R−I color index | +2.1 [2] |
Astrometry | |
Proper motion (μ) |
RA: −64.040±0.087
[3]
mas/
yr Dec.: −23.678±0.072 [3] mas/ yr |
Parallax (π) | 15.4624 ± 0.1163 mas [3] |
Distance | 211 ± 2
ly (64.7 ± 0.5 pc) |
Details | |
Mass | ~0.025 [4] M☉ |
Radius | ~0.25 [5] R☉ |
Luminosity | ~0.002 [5] L☉ |
Temperature | 2550 ± 150 [5] K |
Age | 5·106 to 10·106 [5] years |
Other designations | |
2MASSW J1207334−393254, 2MASS J12073346-3932539, TWA 27
[1] | |
Database references | |
SIMBAD | data |
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. [5] [6]
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. [4] The companion, 2M1207b, is estimated to have a mass of 5–6 Jupiter masses. [7] 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. [4] In December 2005, American astronomer Eric Mamajek reported a more accurate distance (53 ± 6 parsecs) to 2M1207 using the moving cluster method. [8] 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. [4]
Like classical T Tauri stars, many brown dwarfs are surrounded by disks of gas and dust which accrete onto the brown dwarf. [9] [10] 2M1207 was first suspected to have such a disk because of its broad Hα line. This was later confirmed by ultraviolet spectroscopy. [10] The existence of a dust disk has also been confirmed by infrared observations [11] and with ALMA. [12] In general, accretion from disks are known to produce fast-moving jets, perpendicular to the disk, of ejected material. [13] 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. [14] 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. [15]
2M1207b shows weak accretion from a disk, inferred from emission lines of hydrogen and helium in medium-resolution NIRSpec data. Surprisingly 2M1207b does not show absorption due to methane, which was predicted to be present for this object. It was suggested that very young objects have a L/T-transition starts at a later spectral type. [16]
Companion (in order from star) |
Mass |
Semimajor axis ( AU) |
Orbital period ( years) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
circumstellar disk | 9.4±1.5 AU | 35+20 −15 ° |
— | |||
b | 5–6 MJ | ≥49.8 ± 1.1 [18] | 633-20046 | 0.02-0.98 | 13-150 ° | — |