HD 47186 is a star with a pair of orbiting exoplanets in the southern constellation of Canis Major. The system is located at a distance of 122 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 4.2 km/s.[4] Although it has an absolute magnitude of 4.64,[2] at the distance of this system the apparent visual magnitude is 7.63;[2] too faint to be seen with the naked eye. It has a high proper motion, traversing the celestial sphere at an angular rate of 0.272″·yr−1.[8]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 06h 36m 08.788s[1] |
| Declination | −27° 37′ 20.27″[1] |
| Apparent magnitude (V) | 7.63[2] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | G6V[3] |
| B−V color index | 0.714±0.002[2] |
| Astrometry | |
| Radial velocity (Rv) | 4.238±0.0003[4] km/s |
| Proper motion (μ) | RA: 21.582 mas/yr[1] Dec.: −262.843 mas/yr[1] |
| Parallax (π) | 26.7476 ± 0.0217 mas[1] |
| Distance | 121.94 ± 0.10 ly (37.39 ± 0.03 pc) |
| Absolute magnitude (MV) | 4.64[2] |
| Details | |
| Mass | 1.05±0.01[5] M☉ |
| Radius | 1.12±0.01[5] R☉ |
| Luminosity | 1.219±0.005[5] L☉ |
| Surface gravity (log g) | 4.35±0.01[5] cgs |
| Temperature | 5,736±21[5] K |
| Metallicity [Fe/H] | 0.23[6] dex |
| Rotational velocity (v sin i) | 1.953[6] km/s |
| Age | 5.5±0.6[5] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
The spectrum of HD 47186 matches a G-type main-sequence star with a stellar classification of G6V.[3] It is an estimated 5.5[5] billion years old and is spinning with a projected rotational velocity of 2 km/s.[6] The star has 5% greater mass and a 12% larger girth compared to the Sun.[5] The abundance of iron, a measure of the star's metallicity, is 1.7 times more than the Sun, making it metal-rich.[6] HD 47186 is radiating 1.2 times the luminosity of the Sun from its photosphere at an effective temperature of 5,736 K.[5]
Planetary system
Announced in June 2008, two extrasolar planets were discovered orbiting the star. Both planets are less massive than Jupiter. The inner planet HD 47186 b orbits close to the star and is termed a “hot Neptune”. The outer planet HD 47186 c orbits in a similar distance from the star as the asteroid Vesta, at around 2.4 AU. The inner planet orbits in a circular path while the outer planet orbits in an eccentric path.[9]
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥0.07167 MJ | 0.050 | 4.0845 ± 0.0002 | 0.038 ± 0.020 | — | — |
| c | ≥0.35061 MJ | 2.395 | 1353.6 ± 57.1 | 0.249 ± 0.073 | — | — |
See also
References
Further reading
- Kopparapu, Ravi Kumar; et al. (April 2009). "Stability of Additional Planets in and Around the Habitable Zone of the HD 47186 Planetary System". The Astrophysical Journal Letters. 695 (2): L181–L184. arXiv:0903.3597. Bibcode:2009ApJ...695L.181K. doi:10.1088/0004-637X/695/2/L181.
- "HD 47186". Exoplanets. Archived from the original on 2012-03-18. Retrieved 2008-12-16.