HR 2622 Monocerotis

(The Planet Project)

Mon While HR 2622 Monocerotis is spectroscopically classed as a giant- subgiant, which would make it rather unusual for planet discovery, it has the characteristics of an ordinary hydrogen-fusing dwarf (or possibly subgiant).


The circle shows the location of the class G giant-subgiant (?) star HR 2622, found in the constellation Monoceros. The planet, whose mass is at least 1.13 times that of Jupiter, orbits with a period of 119 days at a close average distance of 0.49 Astronomical Units (73.5 million kilometers, 46 million miles), only 27 percent bigger than the orbit of Mercury. Even though fairly close to its star, the orbit is still modestly eccentric, the planet ranging between 0.63 and 0.35 AU (the latter closer than Mercury is to the Sun).


HR 2622, also called HD 52265, is a sixth magnitude (6.30) star in Monoceros that is curiously classed as a G0 giant-subgiant. Too faint to have a proper or Greek letter name, or even Flamsteed number, it is known best by its numbers in the Bright Star(HR) and the Henry Draper (HD) Catalogues. The class is an anomaly. From a distance of 92 light years, the star shines with a luminosity only 1.96 times that of the Sun (far too small for a giant), with a surface temperature of 6075 Kelvin (300 Kelvin hotter than the Sun), from which we derive a mass about 15 percent higher than solar and also see that the star fits into the realm of the ordinary hydrogen fusing dwarfs, though a subgiant status (core hydrogen fusion shut down) cannot be excluded. Like many of the stars that host planets, HR 2622 is metal-rich, with an iron abundance almost 60 percent greater than the solar value.
Written by Jim Kaler. Return to The Planet Project or go to STARS.