HR 6 Phoenecis

(The Planet Project)

Phe HR 6 is classed as a double star, which would make it odd as a planet host. The companionship, however, is probably just a line- of-sight coincidence.


The circle shows the location of the class G1 subgiant star HR 6, found in the constellation Phoenix. The planet, whose mass is at least 1.36 times that of Jupiter, orbits with a period of 328 days at an average distance of 0.98 Astronomical Units (147 million kilometers, 91.3 million miles), which places it much like the Earth relative to the Sun. The big difference, other than mass, is a much higher orbital eccentricity, which takes the planet between 1.34 and 0.62 AU, the latter 85 percent closer than Venus is to the Sun. Such a swing would make life on Earth impossible (not to mention that life on a Jupiter- like planet would be impossible as well).


HR 6, also called HD 142, is a sixth magnitude (5.70) star in Phoenix that is classed as a G1 subgiant (implying that it has given up core hydrogen fusion). 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 84 light years, the star shines with a luminosity 2.8 times that of the Sun with a surface temperature of 6300 Kelvin (over 500 degrees hotter than the Sun), from which we derive a mass about 1.3 times solar, a radius 1.4 solar, and also see that the star fits better into the realm of the ordinary hydrogen fusing dwarfs more than it does into that of the subgiants. Like many of the stars that host planets, HR 6 is metal-rich, with an iron abundance almost 40 percent greater than the solar value. HR 6 is listed as having a "common proper motion" companion, meaning that the two move through space together, and therefore orbit over a long period of time, rendering HR 6 a true double star. However, the two are gradually separating at an angular rate greater than one would expect, showing that the "companion" is probably just a line-of- sight coincidence. HR 6 is, however, a modest "high velocity star" that speeds along at 70 kilometers per second relative to the Sun, some 4 times higher than average, suggesting it is a visitor from a different part of the Galaxy.
Written by Jim Kaler. Return to The Planet Project or go to STARS.