Gliese 581 b
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| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
| Parent star | ||
| Star | Gliese 581 | |
| Constellation | Libra | |
| Right ascension | (α) | 15h 19m 26s |
| Declination | (δ) | −07° 43′ 20″ |
| Distance | 20.4 ly (6.27 pc) | |
| Spectral type | M2.5V | |
| Orbital elements | ||
| Semimajor axis | (a) | 0.041 AU |
| Eccentricity | (e) | 0.02 |
| Orbital period | (P) | 5.366 d |
| Angular distance | (θ) | 6.55 mas |
| Time of periastron | (T0) | 2,451,299.99 JD |
| Semi-amplitude | (K) | 12.42 m/s |
| Physical characteristics | ||
| Mass | (m) | >0.056 MJ (17.8 M⊕) |
| Discovery information | ||
| Discovery date | August 22, 2005 announced November 30, 2005 |
|
| Discoverer(s) | X. Bonfils, T. Forveille, X. Delfosse, S. Udry, M. Mayor, C. Perrier, F. Bouchy, F. Pepe, D. Queloz, J.-L. Bertaux |
|
| Detection method | Doppler Spectroscopy | |
| Discovery status | Published | |
Gliese 581 b is an extrasolar planet orbiting the star Gliese 581.
Contents |
[edit] Discovery
The planet was discovered by a team of French and Swiss astronomers, who announced their findings on November 30, 2005 as a discovery of one of the smallest extrasolar planets ever found, with one conclusion being that planets may be more common around the smallest stars. It was the fifth planet found around a red dwarf star (after Gliese 876's planets and Gliese 436 b). Like Gliese 436 b, it has a mass similar to that of Neptune.
The planet was discovered using the HARPS instrument, with which they found the host star to have a wobble that implied the existence of the planet.
The astronomers published their results in a Letter to the Editor of Astronomy and Astrophysics ("The HARPS search for southern extra-solar planets. VI. A Neptune-mass planet around the nearby M dwarf Gl 581", by X. Bonfils et al., A&A 443, L15, 2005).
[edit] Orbit and mass
Gliese 581 b is about 0.056 times Jupiter's mass (17 times the Earth's mass) which is very similar to Neptune's mass.
It is rather close to Gliese 581 and completes a full orbit in only 5.4 days at a mean distance of about 6 million kilometres (0.041 AU). By comparison, Mercury is at a distance of 58 million kilometres (0.387 AU) and completes an orbit in 88 days.
[edit] Characteristics
Gliese 581 b is about 0.04 AU from its sun.
[edit] References
- Bonfils et al. (2005). "The HARPS search for southern extra-solar planets, VI. A Neptune-mass planet around the nearby M dwarf Gl 581". Astronomy and Astrophysics 443: L15–L18.
