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Star in the constellation Reticulum From Wikipedia, the free encyclopedia
HD 27894 is a single star with a system of orbiting exoplanets, located in the southern constellation of Reticulum. It is too faint to be seen with the naked eye at an apparent visual magnitude of 9.36.[1] This system lies at a distance of 142.5 light years from the Sun, as determined via parallax measurements, and is drifting further away with a radial velocity of 83 km/s.[5]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Reticulum[1] |
Right ascension | 04h 20m 47.046s[2] |
Declination | −59° 24′ 39.02″[2] |
Apparent magnitude (V) | 9.36[1] |
Characteristics | |
Spectral type | K2 V[3] |
U−B color index | +0.90[4] |
B−V color index | +1.003±0.002[1] |
Astrometry | |
Radial velocity (Rv) | 82.785±0.0008[5] km/s |
Proper motion (μ) | RA: 182.473±0.012 mas/yr[2] Dec.: 270.012±0.017 mas/yr[2] |
Parallax (π) | 22.8888 ± 0.0121 mas[2] |
Distance | 142.50 ± 0.08 ly (43.69 ± 0.02 pc) |
Absolute magnitude (MV) | 6.225[6] |
Details | |
Mass | 0.83±0.03[7] M☉ |
Radius | 0.79±0.02[7] R☉ |
Luminosity | 0.33±0.01[7] L☉ |
Surface gravity (log g) | 4.56±0.03[7] cgs |
Temperature | 4,923±32[7] K |
Metallicity [Fe/H] | +0.30±0.07[6] dex |
Rotation | 44 days[6] |
Rotational velocity (v sin i) | ≤ 1.5[6] km/s |
Age | 7.7±2.3[8] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
The spectrum of HD 27894 presents as a K-type main-sequence star, an orange dwarf,[6] with a stellar classification of K2 V.[3] This is a quiescent solar-type star that displays no significant magnetic activity in its chromosphere[9] and is spinning slowly with a rotation period of roughly 44 days.[6] The abundance of iron in the star is much higher than in the Sun, an indicator that it is metal-rich.[6] It has 83% of the mass of the Sun and 79% of the Sun's radius. The star is radiating 33% of the luminosity of the Sun from its photosphere at an effective temperature of 4,923 K.[7]
In 2005, the Geneva Extrasolar Planet Search Team announced the discovery of an extrasolar planet orbiting the star.[6] In 2017, the discovery of two additional exoplanets was announced. One is very close to the star like the one discovered earlier, while the other one orbits the star at a much larger distance. It is the first system where such a large gap between orbital distances has been found.[9][10] In 2022, the inclination and true mass of HD 27894 d were measured via astrometry. The study only found strong evidence for planets b and d.[11]
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
b | ≥0.665+0.009 −0.007 MJ |
0.125±0.0001 | 18.02+0.01 −0.02 |
0.047+0.012 −0.008 |
— | — |
c | ≥0.162+0.011 −0.040 MJ |
0.198±0.001 | 36.07+0.26 −0.09 |
0.015+0.020 −0.002 |
— | — |
d | 6.493+0.987 −0.353 MJ |
5.362+0.206 −0.223 |
5019.5+32.6 −31.1 |
0.343+0.031 −0.026 |
101.524+14.742 −31.503° |
— |
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