Epsilon Reticuli
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Reticulum |
| Right ascension | 4h 16m 29.029s[1] |
| Declination | –59° 18′ 07.76″[1] |
| Apparent magnitude (V) | 4.44[2] / 12.5 |
| Characteristics | |
| Spectral type | K2 IV[3] / D |
| U−B color index | +1.07[2] |
| B−V color index | +1.08[2] |
| Astrometry | |
| Radial velocity (Rv) | +29.3[4] km/s |
| Proper motion (μ) | RA: –47.53 ± 0.17[1] mas/yr Dec.: –167.58 ± 0.17[1] mas/yr |
| Parallax (π) | 54.83 ± 0.15[1] mas |
| Distance | 59.5 ± 0.2 ly (18.24 ± 0.05 pc) |
| Absolute magnitude (MV) | 0.87[5] |
| Details | |
| Surface gravity (log g) | 3.3[6] cgs |
| Temperature | 4,749[6] K |
| Metallicity [Fe/H] | +0.22[6] dex |
| Rotational velocity (v sin i) | 2.80[7] km/s |
| Age | 10[3] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Reticuli (Epsilon Ret, ε Reticuli, ε Ret) is a double star approximately 59 light-years away in the constellation of Reticulum. The primary component is an orange subgiant, while the secondary is a white dwarf. The two stars share a common motion through space and hence most likely form a binary star system.[3] The brighter 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.
Star system
The primary component is a subgiant star with a stellar classification of K2 IV.[3] The fusing of hydrogen in its core is coming to an end and it is in the process of expanding as a red giant. (The NStars project gave it a classification of K2 III, which would make it a giant star.)[9]
The secondary component is a white dwarf star located at a separation of at least 240 AU from the primary.[3] It has a surface temperature between 9000 and 17000 K.
Planetary system
The inner solar system superimposed behind the orbits of the planet Epsilon Reticuli b (and several others).
On December 11, 2000, a team of astronomers announced the discovery of a planet Epsilon Reticuli b.[10] With a minimum mass of 1.17 that of Jupiter, 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.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | >1.56 ± 0.14 MJ | 1.271 ± 0.073 | 428.1 ± 1.1 | 0.060 ± 0.043 | — | — |
References
- 1 2 3 4 5 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
- 1 2 3 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99), Bibcode:1966CoLPL...4...99J.
- 1 2 3 4 5 Chauvin, G.; 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", Astronomy and Astrophysics 475 (2): 723–727, arXiv:0710.5918, Bibcode:2007A&A...475..723C, doi:10.1051/0004-6361:20067046.
- ↑ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953QB901.W495......
- ↑ Elgarøy, Øystein; Engvold, Oddbjørn; Lund, Niels (March 1999), "The Wilson-Bappu effect of the MgII K line - dependence on stellar temperature, activity and metallicity", Astronomy and Astrophysics 343: 222–228, Bibcode:1999A&A...343..222E.
- 1 2 3 Randich, S.; et al. (August 1999), "Lithium in population I subgiants", Astronomy and Astrophysics 348: 487–500, Bibcode:1999A&A...348..487R.
- 1 2 Butler, R. P.; 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.
- ↑ "eps Ret -- Star in double system", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-05-23.
- ↑ Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
- ↑ Butler, R. P.; et al. (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.
- ↑ Schwarz; 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.
External links
- "Epsilon Reticuli". solstation. Retrieved 27 November 2013.
Coordinates: 
04h 16m 29.03s, −59° 18′ 07.76″
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