HD 50554 Geminorum

(The Planet Project)



The upper circle shows the location of the class F dwarf star HD 50554, found in the constellation Gemini, the star of interest at dead center. The star's planet, with a mass at least 4.9 times that of Jupiter, orbits with a period of 1279 days, or 3.50 years, at an average distance of 2.38 Astronomical Units (357 million kilometers, 222 million miles), or 56 percent greater than the size of Mars's path around the Sun. A fairly high orbital eccentricity takes the planet from as far as 3.38 AU from its parent star to 1.38 AU.


HD 50554 is a seventh magnitude (6.86) class F8 dwarf star in Gemini that lies just below the limit of naked eye vision, but is plenty bright enough to find with binoculars. Too faint to have a proper or Greek letter name, or even Flamsteed number, it is known best by its number in Henry Draper (HD) Catalogue . From a distance of 101 light years, it shines with a luminosity 1.43 times that of the Sun, but with a higher surface temperature of 6025 Kelvin, some 250 Kelvin warmer than the Sun. That combination gives a radius and a mass both 10 percent greater than solar. Unlike most stars with planets, which are metal-enhanced, the iron abundance of HD 50554 is very close to the solar value.

Pollux and HR 2877 Geminorum, near the lower edge of the picture, also have orbiting planets.
Written by Jim Kaler. Return to The Planet Project or go to STARS.