HD 156668 b
|Extrasolar planet||List of extrasolar planets|
|Right ascension||(α)||17h 17m 40s|
|Declination||(δ)||+29° 13′ 38″|
|Distance||78.5 ± 2.0 ly
(24.1 ± 0.6 pc)
|Minimum mass||(m sin i)||3.1 ± 0.4 M⊕|
|Semimajor axis||(a)||0.0211 ± 0.0002 AU|
|Orbital period||(P)||1.26984 ± 0.00007 d|
|Time of conjunction||(Tc)||2454718.57 ± 0.11 JD|
|Semi-amplitude||(K)||2.2 ± 0.3 m/s|
|Discoverer(s)||Howard et al.|
|Discovery method||Doppler Spectroscopy|
|Discovery site||Keck Observatory|
HD 156668 b is an extrasolar planet orbiting the star HD 156668 78.5 light-years away in the constellation Hercules. It has a minimum mass of 3.1 Earth masses. At the time of discovery it was the second least massive planet discovered by the radial velocity method, subject to the mass/inclination degeneracy that affects radial velocity measurements. The only radial velocity planet less massive than this planet is Gliese 581 e, which was discovered on April 21, 2009, and has a minimum mass of 1.94 Earth masses. In addition to this, it has the lowest semi-amplitude, or the speed of the stellar wobble caused by planet's gravity tugging on the star determined by radial velocity, at 2.2 m/s. This planet was discovered on January 6, 2010; it is the 8th planet discovered in 2010 after the first five planets detected by Kepler on January 4 and two planets around HD 9446 on January 5.
- Rebekah et al. (2010-05-21). "Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e". arXiv:1005.4050.
- Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Howard Isaacson, Jeff A. Valenti, Jay Anderson, Nikolai E. Piskunov (2010). "The NASA-UC Eta-Earth Program: II. A Planet Orbiting HD 156668 with a Minimum Mass of Four Earth Masses". arXiv:1003.3444v1 [astro-ph.EP].
- "Second Smallest Exoplanet Found To Date At Keck". W.M. Keck Observatory. 2010-01-07. Retrieved 2010-01-07.
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