HD 69830 d
From Wikipedia, the free encyclopedia
| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
 |
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| Parent star | ||
| Star | HD 69830 | |
| Constellation | Puppis | |
| Right ascension | (α) | 08h 18m 23.9473s |
| Declination | (δ) | −12° 37′ 55.824″ |
| Distance | 41 ly (12.6 pc) | |
| Spectral type | K0V | |
| Orbital elements | ||
| Semimajor axis | (a) | 0.63 AU |
| Eccentricity | (e) | 0.07 ± 0.07 |
| Orbital period | (P) | 197 ± 3 d |
| Angular distance | (θ) | 50 mas |
| Longitude of periastron |
(ω) | 224 ± 61° |
| Time of periastron | (T0) | 24513358 ± 34 JD |
| Semi-amplitude | (K) | 2.20 ± 0.19 m/s |
| Physical characteristics | ||
| Mass | (m) | >0.058 MJ |
| Temperature | (T) | ~284 K |
| Discovery information | ||
| Discovery date | May 18, 2006 | |
| Discoverer(s) | Lovis et al. | |
| Detection method | HARPS | |
| Discovery status | confirmed | |
HD 69830 d is an extrasolar planet orbiting the orange dwarf star HD 69830 every 197 days. It is the outermost known planet in its planetary system and possibly lies within its habitable zone.
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[edit] Discovery
Planet HD 69830 d was discovered in 2006.
[edit] Orbit and mass
The planet's orbit has a low eccentricity, similar to the planets in our solar system. The semimajor axis of the orbit is only 0.63 AU, similar to that of Mercury in our solar system. However HD 69830 is a less massive and energetic star than the Sun's, thereby putting the planet within its habitable zone.
[edit] Characteristics
Given the planet's Neptune-type mass, it is likely that HD 69830 d is a gas giant with no solid surface. Since the planet has only been detected indirectly through its gravitational effects on the star, properties such as its radius, composition and temperature are unknown. Assuming a composition similar to Neptune or Uranus and an environment close to chemical equilibrium, it is predicted that the atmosphere of HD 69830 d is mainly hydrogen and helium along with rich factors of methane, though cooler regions of the planet may be able to form water clouds.
HD 69830 d lies within the habitable zone of its parental star, HD 69830 as defined by the ability of an Earth-mass planet to retain liquid water at its surface. While the prospects for life on a gas giant are unknown, large moons may be able to support a habitable environment. Models of tidal interactions between a hypothetical moon, the planet and the star suggest that large moons should be able to survive in orbit around HD 69830 d for the lifetime of the system.
[edit] References In Popular Culture
In the Bestiarum included with the special editions of Halo 3, HD 69830 is described as the home star of the Jackals, specifically stating they come from a hypothetical moon of the third planet at the inner edge of the asteroid belt.
[edit] See also
[edit] References
- Lovis et al. (2006). "An extrasolar planetary system with three Neptune-mass planets". Nature 441: 305–309. doi:.
