Epsilon Reticuli
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Reticulum |
| Right ascension | 4h 16m 29.03s |
| Declination | -59° 18′ 07.76″ |
| Apparent magnitude (V) | 4.44 / 12.5 |
| Characteristics | |
| Spectral type | K2IVa / D |
| Astrometry | |
| Distance | 59.45 ly (18.23 pc) |
| Other designations | |
|
HR 1355, HD 27442, HIP 19921
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| Database references | |
| SIMBAD | data |
Epsilon Reticuli (HD 27442) is a binary system approximately 59 light-years away in the constellation of Reticulum. The primary star is an orange subgiant star, while the secondary star is a white dwarf star. The primary star should be easily visible without optical aid under dark skies in the southern hemisphere. In 2000, an extrasolar planet was confirmed to be orbiting the primary star in the system.
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[edit] Star system
The primary star, Epsilon Reticuli A, is an orange 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.
The companion star, Epsilon Reticuli B, is a white dwarf star located around 240 AU from Epsilon Reticuli A.[1] It has a surface temperature between 9000 and 17000 K.
[edit] Planetary system
On December 11, 2000, a team of astronomers announced the discovery of a planet Epsilon Reticuli b.[2] With a minimum mass of 1.17 that of Jupiter and a similar radius, the planet moves around Epsilon Reticuli with an average separation of 1.16 AUs. The eccentricity of the planet is extremely low (at 0.06), and it completes an orbit every 418 days (or 1.13 years).
Stability analysis shows that the planet's Lagrangian points would be stable enough to host Earth-sized planets, though as yet no trojan planets have been detected in this system.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b | >1.56 ± 0.14 MJ | 1.271 ± 0.073 | 428.1 ± 1.1 | 0.060 ± 0.043 |
[edit] References
- ^ Chauvin et al.; Lagrange, A.-M.; Udry, S.; Mayor, M. (2007). "Characterization of the long-period companions of the exoplanet host stars: HD 196885, HD 1237 and HD 27442" (abstract). Astronomy and Astrophysics 475 (2): 723–727. Bibcode 2007A&A...475..723C. doi:10.1051/0004-6361:20067046. http://www.aanda.org/articles/aa/abs/2007/44/aa7046-06/aa7046-06.html. (web preprint)
- ^ Butler et al.; Tinney, C. G.; Marcy, Geoffrey W.; Jones, Hugh R. A.; Penny, Alan J.; Apps, Kevin (2001). "Two New Planets from the Anglo-Australian Planet Search". The Astrophysical Journal 555 (1): 410–417. Bibcode 2001ApJ...555..410B. doi:10.1086/321467. http://www.iop.org/EJ/article/0004-637X/555/1/410/53257.html.
- ^ Schwarz et al.; Dvorak, R.; Süli, Á.; Érdi, B. (2007). "Survey of the stability region of hypothetical habitable Trojan planets" (PDF). Astronomy and Astrophysics 474 (3): 1023–1029. Bibcode 2007A&A...474.1023S. doi:10.1051/0004-6361:20077994. http://www.univie.ac.at/adg/Research/exotro/aa7994-07.pdf.
- ^ Butler et al.; Wright, J. T.; Marcy, G. W.; Fischer, D. A.; Vogt, S. S.; Tinney, C. G.; Jones, H. R. A.; Carter, B. D. et al (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode 2006ApJ...646..505B. doi:10.1086/504701. http://www.iop.org/EJ/article/0004-637X/646/1/505/64046.html.
[edit] External links
- "Epsilon Reticulum". Interstellar Card. http://home.xtra.co.nz/hosts/Wingmakers/Epsilon%20Reticulum%20Planetary%20System.html. Retrieved 2008-06-11.[dead link]
Coordinates: 
04h 16m 29.03s, −59° 18′ 07.76″
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