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'''HD 219134''' (also known as '''Gliese 892''' or '''HR 8832''') is a ] star in the ] of ]. It is smaller and less luminous than the ], with a ] of K3V, which makes it an orange-hued star. HD 219134 is relatively close to our system, with an estimated distance of 21.25 ]s. This star is close to the limit of ] 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 ]s.<ref name=mnras389_2_869/>
'''HD 219134''' (also known as '''Gliese 892''' or '''HR 8832''') is a ] star in the ] of ]. It is smaller and less luminous than our ], with a ] of K3V, which makes it an orange-hued star. HD 219134 is relatively close to our system, with an estimated distance of 21.25 ]s. This star is close to the limit of ] 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 ]s.<ref name=mnras389_2_869/>
== Planetary system ==
== Planetary system ==
Revision as of 17:36, 16 October 2022
Main-sequence star in the constellation Cassiopeia
HD 219134
Star HD 219134 (circled) lies just off the "W" shape of the constellation Cassiopeia.
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.
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). 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. 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.
The conservative habitable zone (CHZ) of HD 219134 is predicted to extend from 0.516 to 0.948 AU. None of the planets found orbiting the star are inside this habitable zone, although HD 219134 g orbits closest, but slightly interior, to the inner edge of the more optimistic empirical habitable zone, or recent Venus as it is sometimes described, which lies at 0.408 AU. The planet also appears to be significantly more massive than Earth and therefore it likely retains a dense atmosphere. It is probably tidally locked with as yet no planetary mass satellites discovered in orbit.
^ 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.
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.
Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1, Bibcode:1999VeARI..35....1W.
Dietrich, Jeremy; Apai, Dániel; Malhotra, Renu (2021). "An Integrative Analysis of the HD 219134 Planetary System and the Inner Solar System: Extending DYNAMITE with Enhanced Orbital Dynamical Stability Criteria". arXiv:2112.05337 .
Notes
The NASA Exoplanet Archive redesignated Vogt's d & f as f & g for consistency with Motalebi et al., and initially incorrectly listed Vogt's g as a separate planet from Motalebi's e due to the difference in reported parameters, introducing the designation h for it. The Exoplanet Archive designations have been used in subsequent papers on this system. (See also the Johnson et al. 2016 reference.)
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