HD 187123 is a star almost identical to the Sun, in the constellation Cygnus, around which has been discovered a planet with at least half the mass of Jupiter. At one ninth the average separation distance of Mercury from the Sun, HD 187123 b orbits more closely to its host star than any other planet discovered up to that time.1 See also exoplanets.
|Distance||156.3 light-years (47.92 pc)|
|Position||R.A. 19h 46m 58.11s; Dec. +34° 25' 10.29"|
|Other catalog designations||BD+34°3708, HIP 97336, SAO 68845|
|Mass (Jupiter=1)||> 0.52|
|Semi-major axis||0.042 AU (6.3 million km, 3.9 million miles)|
|Orbital period||3.097 days|
|Eccentricity||0.03 ± 0.003|
|Discovery||1998, Butler et al., SFSU Planet Search, Keck|
1. Butler, P., Marcy, G., Vogt, S., and Apps, K. "A Planet with a 3.1-day Period Around a Solar Twin," Publications of the Astronomical Society of the Pacific, 110, 1389 (1998).