HD 210277 Aquarii

(The Planet Project)



The circle toward lower right shows the location of the class G dwarf HD 210277 Aquarii in the constellation Aquarius. The star's planet has a mass at least 1.28 times that of Jupiter and orbits with a period of 1.20 years at an average distance from its star of 1.10 Astronomical Units (165 million kilometers, 102 million miles), just 10 percent larger than Earth's orbit around the Sun. A high orbital eccentricity takes the planet between 1.59 and 0.60 AU from its star, the latter 83 percent the size of Venus's orbit.


HD 210277 Aquarii is just-barely seventh magnitude (6.63) G8 dwarf (sometimes called a subgiant) in Aquarius. Much too faint to have a proper or Greek letter name, or even Flamsteed number, it is known best by its number in the Henry Draper (HD) Catalogue. From a distance of 69 light years, it shines with a low luminosity of 0.90 times that of the Sun from a surface at 5545 Kelvin (235 degrees cooler than the Sun), which tells of a star with a radius 1.03 solar and a mass of about 0.92 solar. Like most stars with planets, it is rich in metals, its iron abundance (relative to hydrogen) 1.5 times solar.

The circle at upper left shows HR 8734 Piscium, which hosts a hot Jupiter.
Written by Jim Kaler. Return to The Planet Project or go to STARS.