HD 156846
Star in the constellation Ophiuchus
From Wikipedia, the free encyclopedia
HD 156846 is a binary star[8] system in the equatorial constellation of Ophiuchus, positioned a degree SSE of Messier 9.[12] It has a yellow hue and is just barely bright enough to be visible to the naked eye with an apparent visual magnitude of 6.5. The system is located at a distance of 156 light years from the Sun based on parallax. It is drifting closer with a radial velocity of −68.5 km/s, and is predicted to come to within 85.0 light-years in about 476,000 years.[9]
The primary, component A, is a G-type star with a stellar classification of G1V.[6] The absolute visual magnitude of this star is 1.13 magnitudes above the main sequence, indicating it has evolved slightly off the main sequence.[3] It has 1.35 times the mass of the Sun and 2.12 times the Sun's radius.[3] The star is an estimated 2.8[9] billion years old and is spinning with a projected rotational velocity of 5 km/s.[3] It is radiating five[9] times the luminosity of the Sun from its photosphere at an effective temperature of 5,969 K.[3]
The magnitude 14.1 secondary companion, component B, was discovered by the American astronomer R. G. Aitken in 1910.[5] It lies at an angular separation of 5.1″ from the primary, corresponding to a projected separation of 250 AU. This is a red dwarf with a class of M4V and has an estimated 59% of the Sun's mass.[8]
Planetary system
On 26 October 2007, a planet HD 156846 b was found orbiting the primary star by Tamuz, using the radial velocity method.[13] It has an orbital period of 0.98 years and a large eccentricity of 0.85. The estimated mass of this object is, at a minimum, 10.6 times the mass of Jupiter. If it were following the same orbit within the Solar System, it would have a perihelion within the orbit of Mercury and an aphelion outside the orbit of Mars.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | ≥10.57±0.29 MJ | 1.096±0.021 | 359.5546±0.0071 | 0.84785±0.00050 | — | — |