HD 69830 b

HD 69830 b is a Neptune-mass or super-Earth-mass exoplanet orbiting the star HD 69830. It is at least 10 times more massive than Earth. It also orbits very close to its parent star and takes 8²/₃ days to complete an orbit.

HD 69830 b

Discovery
Discovered by	C. Lovis et al.[1]
Discovery date	May 18, 2006
Detection method	Radial velocity
Orbital characteristics
Semi-major axis	0.0764 ± 0.0017 AU (11,430,000 ± 250,000 km)[2]
Eccentricity	0.128±0.028[2]
Orbital period (sidereal)	8.66897±0.00028 d[2]
Time of periastron	2,453,496.8 ± 0.06
Argument of periastron	340 ± 26
Semi-amplitude	3.4±0.1 m/s[2]
Star	HD 69830
Physical characteristics
Mass	≥10.1+0.38 −0.37 M🜨[2]
Temperature	~804 K

Based on theoretical modeling in the 2006 discovery paper, this is likely to be a rocky planet, not a gas giant.^[1] However, other work has found that if it had formed as a gas giant, it would have stayed that way,^[3] and it is now understood that planets this massive are rarely rocky.^[4]

If HD 69830 b is a terrestrial planet, models predict that tidal heating would produce a heat flux at the surface of about 55 W/m². This is 20 times that of Io.^[5]