HD 188753 Ab
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| Extrasolar planet | Lists of extrasolar planets | |
|---|---|---|
 |
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| Parent star | ||
| Star | HD 188753 A | |
| Constellation | Cygnus | |
| Right ascension | (α) | 19h 54m 58.37s |
| Declination | (δ) | +41° 52′ 17.5″ |
| Spectral type | GV | |
| Orbital elements | ||
| Semimajor axis | (a) | 0.0446 ± 0.001 AU |
| Eccentricity | (e) | 0.00 |
| Orbital period | (P) | 3.3481 ± 0.0009 d |
| Inclination | (i) | ?° |
| Longitude of periastron |
(ω) | ?° |
| Time of periastron | (τ) | 2,453,146.81 JD |
| Physical characteristics | ||
| Mass | (m) | >1.14 ± 0.1 MJ |
| Radius | (r) | ? RJ |
| Density | (ρ) | ? kg/m3 |
| Temperature | (T) | 1341 K |
| Discovery information | ||
| Discovery date | 2005 | |
| Discoverer(s) | Konacki et al. | |
| Detection method | Doppler Spectroscopy | |
| Discovery status | Confirmed | |
| Other designations | ||
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Ho 581 Ab, BD+41°3535 Ab
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HD 188753 Ab is an extrasolar planet orbiting the star HD 188753 A.
Contents |
[edit] Discovery
HD 188753 Ab is the first known exoplanet in a triple star system. It was discovered in 2005 by Dr. Maciej Konacki, a Polish astronomer working in the United States. [1] [2].
[edit] Radial velocity
The planet, a gas giant slightly larger than Jupiter, orbits the main star of the HD 188753 system (HD 188753A), in the constellation Cygnus. The stellar trio (yellow, orange, and red) is about 149 light-years from Earth. The planet, which is at least 14% larger than Jupiter, orbits the main star (HD 188753 A) once every 80 hours or so (3.3 days), at a distance of about 8 Gm, a twentieth of the distance between Earth and the Sun.
[edit] Characteristics
The existence of a planet in this system challenges prevailing planet formation models. Current theory suggests that gas giant planets form multiple AU from their central stars. Once formed, some of these planets may migrate close to their stars due to interactions with the protoplanetary disk. Such planets become Hot Jupiters.
The issue with HD 188753 is that its protoplanetary disk would have been truncated at about 1.3 AU from the primary star by the presence of the pair of secondary stars.[citation needed] A gas giant should not have been able to form so close to the primary, and with no disk material beyond 1.3 AU, a planet should not have been able to form beyond that distance to migrate inward. So how did HD 188753 Ab form?
One possibility is that the planet may have formed before the stars had reached their current configuration. Perhaps the pair were once more distant than they are now. Or perhaps the planet was captured somehow.
Further research into this system may provide more clues. But the existence of a planet in a close trinary system like HD 188753 makes it likely that more planets may exist in multiple star systems than had previously been thought.
This world has been nicknamed the "Tatooine Planet" in reference to the multiple suns of Luke Skywalker's homeworld in the movie Star Wars.[citation needed]
[edit] See also
[edit] References
- Konacki M (2005). "An extrasolar giant planet in a close triple-star system". Nature 436 (7048): 230-3. PMID 16015323.
- Hatzes AP, Wuchterl G (2005). "Astronomy: giant planet seeks nursery place". Nature 436 (7048): 182-3. PMID 16015311.
