Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cassiopeia |
Right ascension | 23h 13m 16.97496s [1] |
Declination | +57° 10′ 06.0838″ [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) | −18.68±0.12 [1] km/s |
Proper motion (μ) | RA: 2074.414 mas/yr [1] Dec.: 294.452 mas/yr [1] |
Parallax (π) | 152.8640 ± 0.0494 mas [1] |
Distance | 21.336 ± 0.007 ly (6.542 ± 0.002 pc) |
Absolute magnitude (MV) | 6.46 [5] |
Details | |
Mass | 0.81±0.03 [6] M☉ |
Radius | 0.778±0.005 [6] R☉ |
Luminosity | 0.2646 [6] L☉ |
Surface gravity (log g) | 4.567±0.018 [6] cgs |
Temperature | 4699 [6] K |
Metallicity [Fe/H] | +0.11 (± 0.04) [6] dex |
Rotational velocity (v sin i) | 6.94 [7] km/s |
Age | 11.0 [6] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
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 relatively close to our system, with an estimated distance of 21.34 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. [9]
HD 219134 has a system of six known exoplanets. The innermost planet, HD 219134 b, is a rocky super-Earth based on size (1.6 Earth radii), and density (6.4 grams per cubic cm). [10] [11] 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. [12] [13] Two months later, Vogt et al. published a paper on this system which found a 6-planet solution, with planets b, c & d corresponding to those in Motalebi et al., f & g being new planets, and h corresponding to Motalebi's e but with different, and more accurate, estimated parameters. [14] [15]
A number of 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. [16] [17] While a 2016 study suggested that the radial velocity signal corresponding to planet f might be caused by stellar activity, [15] it has been confirmed by subsequent studies in 2017 [16] and 2021. [18] Planet g has not been reported by subsequent studies, and a 2020 study did not find evidence of its claimed 94-day period, but instead found a period of 192 days. [19]
Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | 4.74±0.19 M🜨 | 0.03876±0.00047 | 3.092926±0.000010 | 0 (fixed) | 85.05±0.09 ° | 1.602±0.055 R🜨 |
c | 4.36±0.22 M🜨 | 0.06530±0.00080 | 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±0.0030 | 46.859±0.028 | 0.138±0.025 | — | — |
g | >11±1 M🜨 | 0.3753±0.0004 | 94.2±0.2 | 0 | — | — |
h (e) [20] | >98 M🜨 | 3.11±0.04 | 2100.6±2.9 | 0.06±0.04 | — | — |
The conservative habitable zone (CHZ) of HD 219134 is estimated to extend from 0.516 to 0.948 AU. [21] [22] None of the planets orbiting the star are confirmed to orbit inside the habitable zone. [23] The planet candidate HD 219134 g may orbit slightly interior to the inner edge of the habitable zone based on its initially published parameters, [14] or may orbit within the habitable zone based on a more recent estimated orbital period of 192 days and semi-major axis of 0.603 AU. [19] This planet is significantly more massive than Earth and therefore it likely retains a dense atmosphere, comparable to the Solar System's ice giants.
HD 88133 is a yellow star with an orbiting exoplanet in the equatorial constellation of Leo. It has an apparent visual magnitude of 8.01, which is too faint to be visible to the naked eye. With a small telescope it should be easily visible. The distance to this system, as measured through parallax, is 240 light years, but it is slowly drifting closer with a radial velocity of −3.6 km/s.
HD 81040 is a star in the equatorial constellation of Leo. With an apparent visual magnitude of +7.73 it is too dim to be visible to the naked eye but can be viewed with a small telescope. The star is located at a distance of 112 light years from the Sun based on parallax. It is drifting further away with a radial velocity of +49 km/s, having come to within 48 light-years some 527,000 years ago.
HD 149143, also called Rosalíadecastro, is a star with a close orbiting exoplanet in the Ophiuchus constellation. Its apparent visual magnitude is 7.89 and the absolute magnitude is 3.87. The system is located at a distance of 239 light years from the Sun based on parallax measurements, and it is drifting further away with a radial velocity of 12 km/s.
HD 85512 is a solitary K-type main-sequence star 36.8 light-years away in the constellation Vela. It is about 1 billion years older than the Sun. It is extremely chromospherically inactive, only slightly more active than Tau Ceti. It exhibits a long-term variability and was thought to host one low-mass planet, although this is now doubtful.
HD 45364 is a star in the southern constellation of Canis Major. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 8.08. The distance to this system is 112 light years based on parallax. It is drifting further away from the Sun with a radial velocity of +16.4 km/s, having come within 49 light-years some 1.5 million years ago.
HD 175167 b is an exoplanet orbiting HD 175167, which is a G type star within the Pavo constellation 232 light-years away from the Earth. The planet was discovered by the Magellan Planet Search Program as the astronomical object fit the Keplerian orbital model. During the observations 13 doppler velocity tests were conducted, which showed this object's mass was at least 7.8 Jovian-masses and its orbit has a high eccentricity. The exoplanet takes 3.53 years to complete a full stellar orbit.
HD 190007, also known as Gliese 775, is a star with a close orbiting exoplanet in the constellation of Aquila. Parallax measurements by Gaia put the star at a distance of 41.5 light-years away from the Sun. It is drifting closer with a radial velocity of −30.3 km/s, and is predicted to come within 11.8 light-years in 375,000 years. The star has an absolute magnitude of 6.91, but at its present distance the apparent visual magnitude is 7.46, which is too faint to be viewed with the naked eye.
HD 219134 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 R🜨, and a density of 6.4 g/cm3 and orbits at 21.25 light-years away. The exoplanet was initially detected by the instrument HARPS-N of the Italian Telescopio Nazionale Galileo via the radial velocity method and subsequently observed by the Spitzer telescope as transiting in front of its star. The exoplanet has a mass of about 4.5 times that of Earth and orbits its host star every three days. In 2017, it was found that the planet likely hosts an atmosphere.
HD 219134 h, also known as HR 8832 h, is an exoplanet orbiting around the K-type star HD 219134 in the constellation of Cassiopeia. It has a minimum mass of 108 Earth masses, which indicates that the planet is likely a gas giant. Unlike HD 219134 b and c it is not observed to transit and thus its radius and density are unknown.
LTT 1445 is a triple M-dwarf system 22.4 light-years distant in the constellation Eridanus. The primary LTT 1445 A hosts two exoplanets—one discovered in 2019 that transits the star every 5.36 days, and another found in 2021 that transits the star every 3.12 days, close to a 12:7 resonance. As of October 2022 it is the second closest transiting exoplanet system discovered, with the closest being HD 219134 bc.
HD 164509 is a binary star system in the constellation of Ophiuchus. The primary component has an orbiting exoplanet companion. This system is located at a distance of 175 light years based on parallax measurements, and is drifting further away with a radial velocity of 13.7 km/s. It has an absolute magnitude of 4.64, but at that distance the system has an apparent visual magnitude of 8.10, which is too faint to be seen with the naked eye.
HD 7449 is a binary star system about 126 light-years way. The primary star, HD 7449 A, is a main-sequence star belonging to the spectral class F9.5. It is younger than the Sun. The primary star is slightly depleted of heavy elements, having 80% of solar abundance.
HD 121056, or HIP 67851, is an aging giant star with a pair of orbiting exoplanets located in the southern constellation of Centaurus. This star is dimly visible to the naked eye with an apparent visual magnitude of 6.17. It is located at a distance of 209 light years from the Sun, based on parallax measurements, and is drifting further away with a radial velocity of 5.6 km/s.
HD 106315, or K2-109, is a single star with a pair of close-orbiting exoplanets, located in the constellation of Virgo. Based on parallax measurements, this system lies at a distance of 356 light years from the Sun. At that range, the star is too faint to be seen with the naked eye, as it has an apparent visual magnitude of 8.95. But it is slowly drifting closer with a radial velocity of −3 km/s. As of 2020, multiplicity surveys have not detected any stellar companions to HD 106315.