Gliese 581 b
|Extrasolar planet||List of extrasolar planets|
Second 'artists concept' as possible "hot-ice" planet
|Right ascension||(α)||15h 19m 26s|
|Declination||(δ)||−07° 43′ 20″|
|Distance||20.3 ± 0.3 ly
(6.2 ± 0.1 pc)
|Temperature||(T)||3480 ± 48 K|
|Metallicity||[Fe/H]||-0.33 ± 0.12|
|Age||7 – 11 Gyr|
Epoch JD 2451409.762
|Semimajor axis||(a)||0.0406163 ± 0.0000013 AU|
|Orbital period||(P)||5.36841 ± 0.00026 d
|Mean anomaly||(M)||276.1 ± 4.9°|
|Semi-amplitude||(K)||12.45 ± 0.21 m/s|
|Minimum mass||(m sin i)||15.6 ± 0.3 M⊕|
|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,
|Discovery method||Doppler Spectroscopy|
HO Librae b, HO Lib b, BD−07°4003 b, GJ 581 b, HIP 74995 b, LFT 1195 b, LHS 394 b, LPM 564 b, LTT 6112 b, NLTT 39886 b, TYC 5594-1093-1 b, Wolf 562 b
Gliese 581 b or Gl 581 b is an extrasolar planet orbiting the star Gliese 581. It is the first planet of either four (possibly six) discovered in the system so far, and the second in order from the star (magnitude of 0.9 NY Units).
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).
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.
Orbit and mass
Gliese 581 b is at minimum about 16 times the Earth's mass, similar to Neptune's mass. It does not transit its star, implying that its inclination is less than 88.1 degrees. Dynamical simulations of the Gliese 581 system assuming that the orbits of the four planets are coplanar show that the system becomes unstable if its component masses exceed 1.6 – 2 times their minimum masses. This is primarily due to the close separation between planets b and e. For Gliese 581 b, the upper mass limit is 30.4 Earth masses, or about 77% more massive than Neptune.
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.
Gliese 581 b is about 0.04 AU from its sun. It is likely close to Gliese 436 b in mass, temperature, and (with Gliese 876 d) susceptibility to solar effects such as coronal mass ejection. Since Gliese 581 b does not transit, nothing more can be said of it yet. At the least, given that Gliese 581 b orbits alongside five other planets (Gliese 581 e, c, g, d, f) and that Gliese 436 b (thus far) stands alone, their formation must have differed.
- Gliese 229
- Gliese 436 b
- Gliese 876 b
- Gliese 876 c
- Gliese 876 d
- Gliese 581 g
- Habitability of red dwarf systems
- Vogt, S. S.; et al. (2010). "The Lick-Carnegie Exoplanet Survey: A 3.1 M⊕ Planet in the Habitable Zone of the Nearby M3V Star Gliese 581". arXiv:1009.5733 [astro-ph.EP].
- X. 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 Letters 443 (3): L15–L18. arXiv:astro-ph/0509211. Bibcode:2005A&A...443L..15B. doi:10.1051/0004-6361:200500193.
- M. Lopez-Morales et al. (2006). "Limits to Transits of the Neptune-mass planet orbiting Gl 581". Publications of the Astronomical Society of the Pacific 118 (849): 1506–1509. arXiv:astro-ph/0609255. Bibcode:2006PASP..118.1506L. doi:10.1086/508904.
- M. Mayor et al. (2009). "The HARPS search for southern extra-solar planets XVIII: An Earth-mass planet in the GJ 581 planetary system". Astronomy and Astrophysics 507 (1): 487–494. arXiv:0906.2780. Bibcode:2009A&A...507..487M. doi:10.1051/0004-6361/200912172.
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