2M1207b
2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth. It is one of the first candidate exoplanets to be directly observed (by infrared imaging). It was discovered in April 2004 by the Very Large Telescope (VLT) at the Paranal Observatory in Chile by a team from the European Southern Observatory led by Gaël Chauvin. It is believed to be from 5 to 6 times the mass of Jupiter and may orbit 2M1207 at a distance roughly as far from the brown dwarf as Pluto is from the Sun.
Size comparison of 2M1207b with Jupiter. | |
| Discovery | |
|---|---|
| Discovered by | Chauvin et al. |
| Discovery site | Paranal Observatory, Chile |
| Discovery date | April 2004 |
Detection method | Imaged |
| Orbital characteristics | |
Semi-major axis | 24–231 AU (3.6×109–3.46×1010 km) |
| Eccentricity | 0.02–0.98 |
Orbital period (sidereal) | 633–20046 y |
| Inclination | 13–150 |
Longitude of ascending node | 7–174 |
| 2107.69–12883.36 | |
| 4–176 | |
| Star | 2M1207 |
| Physical characteristics | |
Mean radius | 1.15 RJ |
| Mass | 5.5±0.5 MJ |
| Temperature | 1200 K |
Spectral type | mid-to-late L |
| Atmosphere | |
| Composition by volume | hydrogen, water, carbon monoxide, helium |
The object is a very hot gas giant; the estimated surface temperature is roughly 1200 K (930 °C or 1700 °F), mostly due to gravitational contraction. Its mass is well below the calculated limit for deuterium fusion in brown dwarfs, which is 13 Jupiter masses. The projected distance between 2M1207b and its primary is around 40 AU (similar to the mean distance between Pluto and the Sun). Its infrared spectrum indicates the presence of water molecules in its atmosphere. The object is not a likely candidate to support life, either on its surface or on any satellites.