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Gliese 581
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A nearby red dwarf in the constellation of Libra around which have been found three extrasolar planets, including one that has only 1½ times the mass of the Earth and is probably capable of supporting liquid water on its surface. The mean surface temperature of this super-Earth, designated Gliese 581c, is estimated to be in the range 0–40°C. Although it orbits a mere 11 million km (6.8 million miles) from the central star, its temperature is moderate because Gliese 581 is much cooler and dimmer than the Sun. The announcement of its discovery, in April 2007, created great excitement among astrobiologists.
The other two known planets in the Gliese 581 system are a 15 Earth-mass world orbiting even closer to the parent star, and an eight Earth-mass planet that lies further out.
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| Host star | |
|---|---|
| Distance | 20.40 light-years (6.26 pc) |
| Spectral type | M2.5V |
| Luminosity | 0.002 Lsun |
| Mass | 0.33 Msun |
| Apparent magnitude | 10.55 |
| Position | R.A. 15h 19m 26.8s, Dec. -07° 43' 20.2" |
| Radial velocity | -9.4 km/s |
| Other designations | HO Librae, HIP 74995, Gl 581, BD-07° 4003 |
| Planets | |||
|---|---|---|---|
| b | c | d | |
| Mass (Jupiter = 1) | >0.056 | >0.0157 | >0.0259 |
| Semimajor axis (AU) | 0.041 | 0.073 | 0.25 |
| Orbital period (days) | 5.366 | 12.91 | 84.4 |
| Eccentricity | 0.00 | 0.0 | 0.2 |
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Related categories
• NOTABLE STARS
• EXTRASOLAR PLANETS
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