HR 8832

HR 8832

Star HR 8832 (circled) lies just off the "W" shape of the constellation Cassiopeia.
Observation data Epoch J2000      Equinox J2000
Constellation	Cassiopeia
Right ascension	23^h 13^m 16.97632^s[1]
Declination	+57° 10′ 06.0823″[1]
Apparent magnitude (V)	5.574[2]
Characteristics
Spectral type	K3 V[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)	152.76 ± 0.29[1] mas
Distance	21.35 ± 0.04 ly (6.55 ± 0.01 pc)
Absolute magnitude (MV)	6.50
Details
Mass	0.794+0.037 −0.022[6] M☉
Radius	0.80±0.04[7] R☉
Luminosity	0.28[note 1] L☉
Surface gravity (log g)	4.50[3] cgs
Temperature	4710[3] K
Metallicity [Fe/H]	+0.20[3] dex
Rotational velocity (v sin i)	6.94[8] km/s
Age	~12.46[6] 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
SIMBAD	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.

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 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]

Planetary system

The HR 8832 planetary system^{[15][16][17][18][19][20] [21]}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	0.012±0.001 MJ	0.038474±8e-07	3.0931±0.0001	0.0+0.13 −0.0	85.058±0.08°	0.1433±0.0077 RJ
c	0.011±0.002 MJ	0.064816±4e-06	6.7635±0.0006	0.0+0.26 −0.0	—	—
f	0.028±0.003 MJ	0.14574±2e-05	22.805±0.005	0.0	—	—
d	0.067±0.004 MJ	0.23508±4e-06	46.71±0.01	0.0	—	—
g	0.034±0.004 MJ	0.3753±0.0004	94.2±0.2	—	—	—
e	0.0117+0.19 −0.006 MJ	2.56+3.41 −0.15	1842.0+4199.0 −292.0	0.34±0.17	—	—
h	0.34 MJ	3.11±0.04	2247.0±43.0	0.06±0.04	—	—

References

1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
2. Oja, T. (August 1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series 65 (2): 405–409, Bibcode:1986A&AS...65..405O.
3. Frasca, A.; et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics 508 (3): 1313–1330, Bibcode:2009A&A...508.1313F, doi:10.1051/0004-6361/200913327.
4. Kukarkin, B. V.; et al. (1981), "Nachrichtenblatt der Vereinigung der Sternfreunde e.V. (Catalogue of suspected variable stars)", Nachrichtenblatt der Vereinigung der Sternfreunde e.V. (1981) (Moscow: Academy of Sciences USSR Shternberg): 0, Bibcode:1981CSV...C......0K.
5. Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb (Astronomisches Rechen-Institut Heidelberg) 35 (35): 1, Bibcode:1999VeARI..35....1W.
6. Takeda, Genya; et al. (February 2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series 168 (2): 297–318, arXiv:astro-ph/0607235, Bibcode:2007ApJS..168..297T, doi:10.1086/509763.
7. Perrin, M.-N.; Karoji, H. (1987), "Stellar radius determination from IRAS 12-micron fluxes", Astronomy and Astrophysics 172: 235–240, Bibcode:1987A&A...172..235P.
8. Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter", Astronomy and Astrophysics 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725.
9. "HR 8832 -- Flare Star", SIMBAD Astronomical Object Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-04-08.
10. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
11. "PIA19832: Location of Nearest Rocky Exoplanet Known". NASA. 30 July 2015. Retrieved 30 July 2015.
12. Chou, Felicia; Clavin, Whitney (30 July 2015). "NASA's Spitzer Confirms Closest Rocky Exoplanet". NASA. Retrieved 31 July 2015.
13. "Cassiopeia's Hidden Gem". Harvard. 30 July 2015. Retrieved 30 July 2015.
14. Vogt; et al. (25 September 2015). "A Six-Planet System Orbiting HD 219134". arXiv:1509.07912 [astro-ph.EP].
15. http://exoplanet.eu/catalog/hd_219134_b/
16. http://exoplanet.eu/catalog/hd_219134_c/
17. http://exoplanet.eu/catalog/hd_219134_d/
18. http://exoplanet.eu/catalog/hd_219134_e/
19. "Planet HD 219134 f". Exoplanet.eu. Retrieved 2015-11-17.
20. "Planet HD 219134 g". Exoplanet.eu. Retrieved 2015-11-17.
21. "Planet HD 219134 h". Exoplanet.eu. Retrieved 2015-11-17.

Notes

1. From $\begin{smallmatrix}L=4 \pi R^2 \sigma T_{\rm eff}^4 \end{smallmatrix}$, where $\begin{smallmatrix}L \end{smallmatrix}$ is the luminosity, $\begin{smallmatrix}R \end{smallmatrix}$ is the radius, $\begin{smallmatrix}T_{\rm eff}\end{smallmatrix}$ is the effective surface temperature and $\begin{smallmatrix}\sigma \end{smallmatrix}$ is the Stefan–Boltzmann constant

External links

• "BD+56 2966 / HR 8832". SolStation. Retrieved November 7, 2005.

Coordinates: 23^h 13^m 16.98^s, +57° 10′ 06.1″