View source for Astronomy:HD 219134 f

{{Short description|Exoplanet located in the constellation Cassiopeia}}
{{Infobox planet
| name                     = HD 219134 f
<!-- DISCOVERY           -->
| discovered               = 2015 November 17
| discovery_method         = radial velocity method
<!-- DESIGNATIONS        -->
<!-- ORBITAL             --> 
| apsis                    = astron
| aphelion                 = 0.1679 (± 0.00908) [[Astronomy:Astronomical unit|AU]]
| perihelion               = 0.1246 (± 0.00908) [[Astronomy:Astronomical unit|AU]]
| semimajor                = 0.1463 (± 0.0018)<ref name="NASAExoplanetArchive"/><br />0.14574 (± 2e-05)<ref name="NASAExoplanetArchive2">{{cite web
 | url=https://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=HD+219134+f&type=CONFIRMED_PLANET
 | title=HD 219134 f
 | work=exoplanetarchive.ipac.caltech.edu
 | access-date=2017-12-24
}}</ref> [[Astronomy:Astronomical unit|AU]]
| eccentricity             = 0.148 (± 0.047)<ref name="NASAExoplanetArchive"/>
| period                   = 22.805 (± 0.005)<ref name=NASAExoplanetArchive>{{cite web
 | url=https://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=HD+219134&type=PLANET_HOST
 | title=HD 219134
 | work=exoplanetarchive.ipac.caltech.edu
 | access-date=2017-12-24
}}</ref> [[Day|d]]
| inclination              = ?<ref name="NASAExoplanetArchive"/>
| star                     = [[Astronomy:HD 219134|HD 219134]]
<!-- PHYS CHARS          --> 
| mean_radius              = >1.31 (± 0.02)<ref name="NASAExoplanetArchive"/> {{Earth radius|link=y}}
| mass                     = >7.30 (± 0.40)<ref name="NASAExoplanetArchive"/> {{Earth mass|link=y}}
| density                  = <17.9 [[Gram|g]] [[Cubic centimetre|cm<sup>−3</sup>]]
| surface_grav             = <4.25 [[Physics:G-force|g]]
| single_temperature       = {{convert|522.6|K|C F}}
<!-- ATMOSPHERE          --> 
<!-- NOTES               --> 
}}
'''HD 219134 f''', also known as '''HR 8832 f''', is an [[Astronomy:Exoplanet|exoplanet]] orbiting around the K-type star [[Astronomy:HD 219134|HD 219134]] in the constellation of [[Astronomy:Cassiopeia (constellation)|Cassiopeia]]. It is a [[Astronomy:Super-Earth|Super-Earth]] with a [[Astronomy:Minimum mass|minimum mass]] of over 7 times that of Earth. Unlike [[Astronomy:HD 219134 b|HD 219134 b]] and [[Astronomy:HD 219134 c|HD 219134 c]] it was not observed by the [[Astronomy:Spitzer Space Telescope|Spitzer Space Telescope]] and thus its radius and density are unknown. Only a minimum radius can be given.

==Characteristics==

===Mass, Radius, and Temperature===
HD 219134 f is known as a Super-Earth, a planet that's more massive than Earth but less massive than [[Astronomy:Uranus|Uranus]] or [[Astronomy:Neptune|Neptune]]. However, because it is not known to transit its star, only the minimum mass can be determined. The planet is at least 7.30 {{Earth mass}}, indicating that it could be anything from a dense rocky planet to a low-density ice giant. Gillon et al. gives the planet a minimum radius of about 1.31 {{Earth radius}}, which would result in an almost impossible density. For a more likely mixed composition of rock, water, and hydrogen, HD 219134 f would have a radius closer to about 2.10 {{Earth radius}}.

Being close to its star, HD 219134 f is hot, with an equilibrium temperature of {{convert|522.6|K|C F}}. Therefore, if a rocky planet, it is too hot for liquid water. It receives about 12 times the stellar flux as Earth.

===Orbit===
HD 219134 f has an orbital period lasting about 22.72 days, only about a quarter of [[Astronomy:Mercury (planet)|Mercury's]], which lasts about 88 days. The planet also has an orbital radius, or semi-major axis, of 0.146 [[Astronomy:Astronomical unit|AU]]. For comparison, Mercury orbits at 0.38 AU, and Earth at 1 AU. Because of this close proximity, HD 219134 f is likely tidally locked. The planet is near a 1:3 resonance with [[Astronomy:HD 219134 c|HD 219134 c]] and a 2:1 resonance with [[Astronomy:HD 219134 d|HD 219134 d]].

===Host Star===
The planet HD 219134 f orbits the K3V orange dwarf HD 219134, also known as HR 8832. It is 79% the radius and 80% the mass of the Sun with 28% the luminosity. It has a temperature of 4699 K and is around 12.5 billion years old or less. For comparison, the Sun has a temperature of 5778 K and is 4.55 billion years old.

The apparent magnitude of the star, or how bright it appears from Earth, is around 5. Therefore, it is only just visible to the unaided eye.

==References==
{{reflist}}

{{HD 219134}}
{{2015 in space}}

[[Category:Cassiopeia (constellation)]]
[[Category:Exoplanets detected by radial velocity]]

{{Sourceattribution|HD 219134 f}}