Epoch J2000 Equinox J2000
|Right ascension||23h 13m 16.97632s|
|Declination||+57° 10′ 06.0823″|
|Apparent magnitude (V)||5.574|
|U−B color index||+0.902|
|B−V color index||+0.983|
|Radial velocity (Rv)||–18.5 km/s|
|Proper motion (μ)|| RA: +2075.07±0.33 mas/yr |
Dec.: +295.45±0.25 mas/yr
|Parallax (π)||152.76 ± 0.29 mas|
|Distance||21.35 ± 0.04 ly |
(6.55 ± 0.01 pc)
|Absolute magnitude (MV)||6.46|
|Surface gravity (log g)||4.567±0.018 cgs|
|Metallicity [Fe/H]||+0.11 (± 0.04) dex|
|Rotational velocity (v sin i)||6.94 km/s|
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.
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). 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. 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.[note 1] 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.
(in order from star)
|b||4.74±0.19 M⊕||0.03876±0.00047||3.092926±0.000010||0 (fixed)||85.05±0.09°||1.602±0.055 R⊕|
|c||4.36±0.22 M⊕||0.06530±0.00080||6.76458±0.00033||0.062±0.039||87.28±0.10°||1.511±0.047 R⊕|
The Circumstellar habitable zone of HD 219134 is predicted to extend from 0.372 to 1.153 AU. Of the planets found orbiting the star, the unconfirmed HD 219134 g orbits within the inner edge at a relative distance similar to Earth, though it appears to be significantly more massive likely retaining a dense atmosphere and probably tidally locked with no planetary mass satellites discovered in orbit around it.