HD 219134
 Star HD 219134 (circled) lies just off the "W" shape of the constellation Cassiopeia. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 13m 16.97632s[1] |
| Declination | +57° 10′ 06.0823″[1] |
| Apparent magnitude (V) | 5.574[2] |
| Characteristics | |
| Spectral type | K3V[3] |
| U−B color index | +0.902[2] |
| B−V color index | +0.983[2] |
| Variable type | Suspected[4] |
| Astrometry | |
| Radial velocity (Rv) | –18.5[5] km/s |
| Proper motion (μ) | RA: +2075.07±0.33[1] mas/yr Dec.: +295.45±0.25[1] mas/yr |
| Parallax (π) | 152.8640 ± 0.0494[6] mas |
| Distance | 21.336 ± 0.007 ly (6.542 ± 0.002 pc) |
| Absolute magnitude (MV) | 6.46[7] |
| Details | |
| Mass | 0.81±0.03[8] M☉ |
| Radius | 0.778±0.005[8] R☉ |
| Luminosity | 0.2646[8] L☉ |
| Surface gravity (log g) | 4.567±0.018[8] cgs |
| Temperature | 4699[8] K |
| Metallicity [Fe/H] | +0.11 (± 0.04)[8] dex |
| Rotational velocity (v sin i) | 6.94[9] km/s |
| Age | 11.0[8] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 219134 (also known as Gliese 892 or HR 8832) is a main-sequence star in the constellation of Cassiopeia. It is smaller and less luminous than our Sun, with a spectral class of K3V, which makes it an orange-hued star. HD 219134 is relatively close to our system, with an estimated distance of 21.25 light years. This star is close to the limit of apparent magnitude that can still be seen by the unaided eye. The limit is considered to be magnitude 6 for most observers. This star has a magnitude 9.4 optical companion at an angular separation of 106.6 arcseconds.[11]
Planetary system[]
HD 219134 has a system of 6 exoplanets. The innermost planet, HD 219134 b, is a rocky super-Earth based on size (1.6 times the size of Earth), and density (6.4 grams per cubic cm).[12][13] This and three additional exoplanets; one super-Earth (designated c and later found to be rocky as well), one Neptunian world (d), and one Jovian world (e); were deduced using HARPS-N radial velocity data by Motalebi et al. in 2015.[14][15] Two months later, Vogt et al. published a paper on this system which found a 6-planet solution, with planets b & c corresponding to those in Motalebi et al., e & g corresponding to Motalebi's d & e, and d & f being new planets.[16][note 1][17] A total of four independent studies have been done regarding the planetary system of HD 219134, with some of their results conflicting with each other. As of March 2017, the star is known to have at least 5 planets, with two of them (HD 219134 b and c) known to be transiting, rocky super-Earths. The previously reported planets HD 219134 g and h were not reported in following HARPS-N analyses in March 2017 by Gillon et al.[18][19]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 4.74±0.19 M
|