HD 66428
Star in the constellation Monoceros
From Wikipedia, the free encyclopedia
HD 66428 is a G-type subgiant star located approximately 174 light-years away in the constellation of Monoceros. This star is similar to the Sun with an apparent magnitude of 8.25, an effective temperature of 5,705±27 K and a solar luminosity 1.28. Its absolute magnitude is 11.1 while its U-V color index is 0.71. It is considered an inactive star and it is metal-rich ([Fe/H] = 0.310).[3][6][7] This star has a precise mass of 1.14552 solar masses. This precision comes from the Corot mission that measured asteroseismology.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Monoceros[1] |
| Right ascension | 08h 03m 28.66767s[2] |
| Declination | −01° 09′ 45.7581″[2] |
| Apparent magnitude (V) | 8.25[3] |
| Characteristics | |
| Evolutionary stage | subgiant[2] |
| Spectral type | G8IV(+G)[4] |
| Astrometry | |
| Radial velocity (Rv) | 44.26±0.13[2] km/s |
| Proper motion (μ) | RA: −65.766±0.029 mas/yr[2] Dec.: −206.999±0.019 mas/yr[2] |
| Parallax (π) | 18.7661±0.0312 mas[2] |
| Distance | 173.8 ± 0.3 ly (53.29 ± 0.09 pc) |
| Absolute magnitude (MV) | +4.56[1] |
| Details | |
| Mass | 1.09±0.02[5] M☉ |
| Radius | 1.13±0.03[5] R☉ |
| Luminosity | 1.28±0.01[5] L☉ |
| Surface gravity (log g) | 4.37±0.03[5] cgs |
| Temperature | 5,773±55[5] K |
| Age | 4.1±1.4[5] Gyr |
| Other designations | |
| BD−00°1891, HIP 39417, LTT 3038, SAO 135426 | |
| Database references | |
| SIMBAD | data |
Planetary system
In July 2006, the discovery of the extrasolar planet HD 66428 b was published in the Astrophysical Journal. It was found from observations at the W. M. Keck Observatory using the radial velocity method. It has a minimum mass of more than 3 times that of Jupiter and orbits at a distance of 3.47 AU away from the star.[3][8]
In 2015 a refined orbit was determined which led to the discovery of a linear trend in the radial velocities indicating a more distant companion of unknown character,[8] which was determined to be a gas giant planet HD 66428 c or brown dwarf in 2021.[9] In 2022, the inclination and true mass of both planets were measured via astrometry. The orbital period and mass of planet c were found to be significantly lower than the previous higher-error estimates, showing it to be planetary mass and not a brown dwarf.[10]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (years) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 10.946+2.442 −3.845 MJ |
3.395+0.141 −0.157 |
6.214+0.015 −0.016 |
0.471±0.012 | 16.639+10.121 −2.959° |
— |
| c | 1.764+3.404 −0.041 MJ |
9.408+1.945 −1.267 |
28.690+9.206 −5.348 |
0.207+0.097 −0.098 |
93.938+57.003 −55.476° |
— |
