HD 219134 f, also known as HR 8832 f, is an

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

orbiting around the

K-type star In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

HD 219134 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 the Sun, with a spectral class of K3V, which makes it an orange-hued star. HD 219134 is rela ...

in the constellation of Cassiopeia. It is a

Super-Earth A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to ...

with a

minimum mass In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets detected by the radial veloc ...

of over 7 times that of Earth. Unlike

HD 219134 b HD 219134 b (or HR 8832 b) is one of at least five exoplanets orbiting HD 219134, a main-sequence star in the constellation of Cassiopeia. HD 219134 b has a size of about 1.6 , and a density of 6.4 g/cm3 and orbits at 21.25 light-years away. ...

and HD 219134 c it was not observed by the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

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

Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...

Neptune Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...

. However, because it is not known to transit its star, only the minimum mass can be determined. The planet is at least 7.30 , 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 , 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 . Being close to its star, HD 219134 f is hot, with an equilibrium temperature of . 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 Mercury's, which lasts about 88 days. The planet also has an orbital radius, or semi-major axis, of 0.146 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 HD 219134 c and a 2:1 resonance with

HD 219134 d HD 219134 d, also known as HR 8832 d, is an exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. It has a minimum mass over 16 times that of Earth, indicating that it is likely a Hot Neptune. The exoplanet was i ...

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

{{2015 in space Cassiopeia (constellation) Exoplanets discovered in 2015 Exoplanets detected by radial velocity