| 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−Bcolor index | +0.90[4] |
| B−Vcolor index | +1.003±0.002[1] |
| Astrometry | |
| Radial velocity (Rv) | 82.785±0.0008[5] km/s |
| Proper motion (μ) | RA: 182.473±0.012mas/yr[2] Dec.: 270.012±0.017mas/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 | |
| CD−59° 829,HD 27894,HIP 20277,LTT 1953[4] | |
| Database references | |
| SIMBAD | data |
HD 27894 is a singlestar with a system of orbitingexoplanets, located in the southernconstellation ofReticulum. It is too faint to be seen with the naked eye at anapparent visual magnitude of 9.36.[1] This system lies at a distance of 142.5 light years from the Sun, as determined viaparallax measurements, and is drifting further away with aradial velocity of 83 km/s.[5]
Thespectrum of HD 27894 presents as aK-type main-sequence star, an orange dwarf,[6] with astellar classification of K2 V.[3] This is a quiescentsolar-type star that displays no significantmagnetic activity in itschromosphere[9] and is spinning slowly with arotation period of roughly 44 days.[6] The abundance of iron in the star is much higher than in the Sun, an indicator that it ismetal-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 itsphotosphere at aneffective temperature of 4,923 K.[7]
In 2005, theGeneva Extrasolar Planet Search Team announced the discovery of anextrasolar 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 viaastrometry. 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[12] | ≥0.674±0.021 MJ | 0.1286+0.0019 −0.0020 | 18.0071±0.0002 | 0.0334+0.0088 −0.0091 | — | — |
| c[9] | ≥0.162+0.011 −0.040 MJ | 0.198±0.001 | 36.07+0.26 −0.09 | 0.015+0.020 −0.002 | — | — |
| d[12] | 7.58+0.60 −0.56 MJ | 5.514±0.084 | 5,042±19 | 0.3239+0.0092 −0.0089 | 117.8+6.9 −11.0° | — |
