HD 209458 b
Description: HD 209458 b is an exoplanet, specifically a hot Jupiter, that orbits the solar analog HD 209458 in the constellation Pegasus, some 157 light-years from the Solar System. The radius of the planet's orbit is 0.047 AU, or one-eighth the radius of Mercury's orbit. This small orbital distance results in a year that is 3.5 Earth-days long and an estimated surface temperature of about 1,000 °C. Its mass is 220 times that of Earth and its volume is some 2.5 times greater than that of Jupiter. The high mass and volume of HD 209458 b indicate that it is a gas giant.
Physical Properties
Mass (Jupiter mass): 0.73 MJ
Radius (Jupiter radius): 1.39 RJ
Density: 0.362 g/cm³
Equilibrium Temperature: 1459.0 K
Orbital Parameters
Orbital Period: 3.52474859 days
Semi-major Axis: 0.04707 AU
Eccentricity: Unknown
Inclination: 86.71°
Host Star Properties
Host Star: HD 209458
Spectral Type: Unknown
Temperature: 6091.0 K
Stellar Mass: 1.13 M☉
Stellar Radius: 1.18 R☉
Discovery Information
Planet Letter: b
Object ID: 3.11218
Host ID: 2.59237
Discovery Date: 2000-01
Discovery Year: 1999
Discovery Method: Radial Velocity
Discovery Locale: Ground
Discovery Facility: W. M. Keck Observatory
Discovery Instrument: HIRES Spectrometer