Epsilon Reticuli
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Epsilon Reticuli (ε Ret / ε Reticuli) is a 4th magnitude star in the constellation Reticulum. The system is a binary, the primary component being an orange subgiant, and the secondary is probably a red dwarf. The primary star should be easily visible without optical aid under dark skies in southern hemisphere.
The primary star is known to have an extrasolar planet orbiting it.
Contents |
[edit] ε Reticuli A
| Observation data Equinox 2000 |
|
|---|---|
| Constellation | Reticulum |
| Right ascension | 4h 16m 29.03s |
| Declination | -59° 18' 07.76" |
| Apparent magnitude (V) | 4.44 |
| Distance | 59.45 ly (18.23 pc) |
| Spectral type | K2IVa |
| Other designations | |
|
HR 1355, HD 27442,
HIP 19921 |
|
The primary star, ε Reticuli A, is a yellow subgiant 20% more massive than our Sun. Being a subgiant it is ceasing or has already ceased fusing hydrogen in its core. Soon the star will swell up and become a red giant. Despite its advanced stage, it cannot be much older than the Sun.
[edit] ε Reticuli Ab
| Extrasolar planet | Lists of extrasolar planets | |
|---|---|---|
| Orbital elements | ||
| Semimajor axis | (a) | 1.271±0.073 AU |
| Eccentricity | (e) | 0.060±0.043 |
| Orbital period | (P) | 428.1±1.1 d |
| Inclination | (i) | ?° |
| Longitude of periastron |
(ω) | 216° |
| Time of periastron | (τ) | 2,451,963±55 JD |
| Physical characteristics | ||
| Mass | (m) | >1.56±0.14 MJ |
| Radius | (r) | ? RJ |
| Density | (ρ) | ? kg/m3 |
| Temperature | (T) | ? K |
| Discovery information | ||
| Discovery date | 2001 | |
| Discoverer(s) | Butler, Tinney, Marcy et al. |
|
| Detection method | Radial velocity | |
| Discovery status | Published | |
The planet, designated as ε Reticuli Ab, was discovered in 2001 by the Anglo-Australian Planet Search Team using the highly successful radial velocity method. The planet's mass is at least 28% greater than Jupiter's, a more accurate estimate requiring its inclination to be known.
The planet orbits the star in a very Earth-like orbit. However, the planet is certainly a gas giant and life as we know it may not flourish there. The planet might have massive moons (they cannot be detected with current technology) that could have supported life, but as the star aged they became too hot for life.
[edit] ε Reticuli B
| Observation data Equinox 2000 |
|
|---|---|
| Constellation | Reticulum |
| Right ascension | 4h 16m 30.2s |
| Declination | -59° 17' 45" |
| Apparent magnitude (V) | 12.5 |
| Distance | 59.45? ly (18.23? pc) |
| Spectral type | ? |
| Other designations | |
|
n/a
|
|
The companion star, ε Reticuli B is likely a dim red dwarf. Not much information is available on it.
[edit] References
- Butler et al. (2001). "Two New Planets from the Anglo-Australian Planet Search". The Astrophysical Journal 555: 410-417.
- Butler, R. et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646: 505 – 522. (web Preprint)
[edit] External links
- SIMBAD component A entry, component B entry, planet entry
- The Extrasolar Planets Encyclopaedia entry
- ε Reticuli at Extrasolar Visions
- ε Reticuli Ab at Extrasolar Visions
