HR 8832

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.

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  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)152.76 ± 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
SIMBADdata

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 (retracted candidate) >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 — —
gollark: (Small = below 700M parameters)
gollark: I can run small GPT models for us.
gollark: Just have it arrange them into an overly large grid and make some of the connections skip over the empty cells.
gollark: In that case, we can probably apinate the topology somehow.
gollark: Anyway, it could be philosophically a "webring" but topologically have four direction buttons or something.

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, arXiv:0911.0760, 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. Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191.
  7. "HD 219134". exoplanetarchive.ipac.caltech.edu. Retrieved 2017-12-24.
  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" (PDF), Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725.
  9. "HR 8832". SIMBAD. 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". The Astrophysical Journal. 814: 12. arXiv:1509.07912. Bibcode:2015ApJ...814...12V. doi:10.1088/0004-637X/814/1/12.
  15. http://backalleyastronomy.blogspot.com/2017/04/hd-219134-scorecard-5-planets-2.html?m=1
  16. "The Extrasolar Planet Encyclopaedia — HD 219134 b". exoplanet.eu.
  17. "The Extrasolar Planet Encyclopaedia — HD 219134 c". exoplanet.eu.
  18. "The Extrasolar Planet Encyclopaedia — HD 219134 d". exoplanet.eu.
  19. "The Extrasolar Planet Encyclopaedia — HD 219134 e". exoplanet.eu.
  20. "Planet HD 219134 f". Exoplanet.eu. Retrieved 2015-11-17.
  21. "Planet HD 219134 g". Exoplanet.eu. Retrieved 2015-11-17.
  22. "Planet HD 219134 h". Exoplanet.eu. Retrieved 2015-11-17.
  23. Gillon, Michaël; et al. (2017). "Two massive rocky planets transiting a K-dwarf 6.5 parsecs away". Nature Astronomy. 1. 0056. arXiv:1703.01430. Bibcode:2017NatAs...1E..56G. doi:10.1038/s41550-017-0056.

Notes

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