q-1 Eridani

(The Planet Project)



The right-hand circle shows the location of the class F dwarf star q-1 Eridani, known as well in the Bright Star Catalogue as HR 506 and found in the deep southern end of the constellation Eridanus (as well as another planet-holding star, Iota Horologii). The star's planet, with a mass at least 0.91 times that of Jupiter, orbits with a period of 1040 days, or 2.85 years at an average distance of 2.10 Astronomical Units (315 million kilometers, 196 million miles), or 38 percent greater than the size of Mars's path around the Sun. A modest orbital eccentricity takes the planet from as far as 2.48 AU from its parent star to 1.72 AU.


HR 506, q-1 Eridani, is a just-over-the-line sixth magnitude (5.52) class F9 dwarf star in southern Eridanus not far from first magnitude Achernar. The name q-1 is a vestige of Bayer's extended naming system, wherein Roman letters were applied (by him and others) after he ran out of Greek ones. From a distance of 57 light years, it shines with a luminosity 1.53 times that of the Sun, but with a higher surface temperature of 6140 Kelvin, 350 Kelvin warmer than the Sun. That combination gives a radius 10 percent greater than solar and a mass of about 1.15 solar. Unlike most stars with planets, which are metal- enhanced, the iron abundance of HD 50554 is very close to that found in the Sun.
Written by Jim Kaler. Return to The Planet Project or go to STARS.