Epsilon Indi Ab
Epsilon Indi Ab imaged by the James Webb Space Telescope MIRI. The star motif marks the position of its host star; whose light is blocked by a coronagraph. | |
| Discovery | |
|---|---|
| Discovered by | Fabo Feng, et al. |
| Discovery date | 21 March 2018 (suspected since 2002) |
| Radial velocity | |
| Orbital characteristics | |
| 29.2+3.3 −3.4 AU | |
| Eccentricity | 0.399+0.059 −0.076 |
| 180+32 −31 years | |
| Inclination | 105.4°+2.5° −2.4° |
| Star | Epsilon Indi A |
| Physical characteristics | |
| 1.08 RJ | |
| Mass | 7.29+0.60 −0.61 MJ |
| Temperature | 275 K (2 °C; 35 °F) |
Epsilon Indi Ab is a gas giant exoplanet orbiting the star Epsilon Indi A, about 11.9 light-years away in the constellation of Indus. The planet was confirmed to exist in 2018. It orbits at around 30 AU (almost as far as Neptune from the Sun) with a period of around 180 years and a relatively high eccentricity of 0.4, and has a mass around seven times that of Jupiter. It was directly imaged using the James Webb Space Telescope in 2023 and the image was released on 24 July, 2024.
As of 2024, Epsilon Indi Ab is the nearest exoplanet to be directly imaged, and with a temperature of about 275 K (2 °C; 35 °F), is also the coolest exoplanet to be directly imaged, and cooler than all but one imaged brown dwarf (the exception being the planetary-mass WISE 0855−0714). It is predicted, based on evolutionary models, to have a luminosity around to 6.31×10−8 L☉, which together with its effective temperature of 275 K implies a radius of 1.08 RJ.
The Epsilon Indi system also contains a pair of brown dwarfs, Epsilon Indi Ba and Bb, at a wide separation from the primary star. As such, this system provides a benchmark case for the study of the formation of gas giants and brown dwarfs.