HR 8832

HR 8832
PIA19832-StarHD219134-Location-20150730.jpg
Star HR 8832 (circled) lies just off the "W" shape of the constellation Cassiopeia.
Observation data
Epoch J2000      Equinox J2000
ConstellationCassiopeia
Right ascension23h 13m 16.97632s[1]
Declination+57° 10′ 06.0823″[1]
Apparent magnitude (V)5.574[2]
Characteristics
Spectral typeK3V[3]
U−B color index+0.902[2]
B−V color index+0.983[2]
Variable typeSuspected[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)152.76 ± 0.29[1] mas
Distance21.35 ± 0.04 ly
(6.55 ± 0.01 pc)
Absolute magnitude (MV)6.46[6]
Details
Mass0.81±0.03[7] M
Radius0.778±0.005[7] R
Luminosity0.2646[7] L
Surface gravity (log g)4.567±0.018[7] cgs
Temperature4699[7] K
Metallicity [Fe/H]+0.11 (± 0.04)[7] dex
Rotational velocity (v sin i)6.94[8] km/s
Age11.0[7] Gyr
Other designations
BD+56 2966, FK5 875, GCTP 5616.00, Gl 892, HD 219134, HIP 114622, LFT 1767, LHS 71, LTT 16826, SAO 35236.[9]
Database references
data

HR 8832 (or HD 219134, or Gliese 892) 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-red hued star. HR 8832 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.

Companions

This star has a magnitude 9.4 companion at an angular separation of 106.6 arcseconds.[10] The star is reported to host a rocky super-Earth, HD 219134 b, based on size (1.6 times the size of Earth), and density (6.4 grams per cubic cm).[11][12] A further three exoplanets, two super-Earths and one Jovian world, have been deduced using Harps-N radial velocity data.[13] Two more were discovered two months later.[14] A total of four independent studies regarding the planetary system of HR 8832 have been done, with many of their results conflicting with each other. As of March 2017, the star is known to have at least 5 planets, two of them (HD 219134 b and c) known to be transiting, rocky Super-Earths. Two previously reported planets, HD 219134 e and HD 219134 g, were not found in following HARPS-N analyses in March 2017 by Gillon et al.[15]

The HR 8832 planetary system[16][17][18][19][20][21][22]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius [23]
b 4.74 (± 0.19) M 0.038764 (± 0.0047) 3.092926 0 (fixed) 85.058 (± 0.08)° 1.602 (± 0.055) R
c 4.36 (± 0.22) M 0.06530 (± 0.0008) 6.76458 (± 0.00033) 0.062 (± 0.039) 87.28 (± 0.10)° 1.511 (± 0.047) R
f >7.30 (± 0.40) M 0.1463 (± 0.0018) 22.717 (± 0.015) 0.148 (± 0.047)
d >16.17 (± 0.64) M 0.2370 (± 0.003) 46.859 (± 0.028) 0.138 (± 0.025)
g (unconfirmed) >10.8 M 0.3753 (± 0.0004) 94.2 (± 0.2) ~0
e (unconfirmed) >3.72 M 2.56+3.41
−0.15
1842.0+4199.0
−292.0
0.34 (± 0.17)
h >76.0 M 2.96 2121.0 0.06±0.04
Other Languages
asturianu: Gliese 892
Deutsch: HR 8832
español: Gliese 892
فارسی: گلیز ۸۹۲
français: Gliese 892
한국어: 글리제 892
italiano: HD 219134
Lëtzebuergesch: HR 8832
Nederlands: HR 8832
日本語: グリーゼ892
norsk: Gliese 892
polski: HR 8832
português: HR 8832
русский: Глизе 892
slovenčina: Gliese 892
svenska: Gliese 892
中文: 格利泽892