HD 38858
Star in the constellation Orion
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HD 38858 is a star in the Orion constellation. It is a G-type main-sequence star, located at a distance of about 50 light-years. It has an apparent magnitude of 5.97, so it can be seen by the naked eye only in sufficiently dark skies.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Orion[1] |
| Right ascension | 05h 48m 34.94026s[2] |
| Declination | −04° 05′ 40.7218″[2] |
| Apparent magnitude (V) | +5.97[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | G4V[4] |
| U−B color index | +0.10[3] |
| B−V color index | +0.64[3] |
| Astrometry | |
| Radial velocity (Rv) | +31.2[5] km/s |
| Proper motion (μ) | RA: +61.427[2] mas/yr Dec.: −229.291[2] mas/yr |
| Parallax (π) | 65.7446±0.0307 mas[2] |
| Distance | 49.61 ± 0.02 ly (15.210 ± 0.007 pc) |
| Absolute magnitude (MV) | +5.06[6] |
| Details | |
| Mass | 0.886[7] M☉ |
| Radius | 0.9331±0.0162[7] R☉ |
| Luminosity | 0.7943±0.0101[7] L☉ |
| Surface gravity (log g) | 4.36±0.06[4] cgs |
| Temperature | 5,660±20[4] K |
| Metallicity [Fe/H] | −0.27±0.03[4] dex |
| Rotational velocity (v sin i) | 2.61[8] km/s |
| Age | 6.2[9] Gyr |
| Other designations | |
| BD−04°1244, FK5 1155, GJ 1085, HD 38858, HIP 27435, LTT 2380, SAO 132554 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
This system was observed for a dust disc or comet belt in 2009 by the Spitzer Space Telescope; a belt was inferred at 102 AU.[9] It has an inclination of 48°.[10]
The star exhibits a magnetic activity cycle remarkably similar to that of the Sun, with a period of 10.8 years.[11]
Planetary system
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The exoplanet HD 38858 b was discovered in 2011 in orbit in its host star's habitable zone, a zone in which Earth-like conditions (namely the presence of liquid water) on a planet's surface are possible.[13][14] The planet is likely a gas giant, a type of planet which astronomers believe is unlikely to support life as it is currently understood. However, the planet could have a rocky natural satellite capable of sustaining an Earth-like environment.[15]
The existence of this planet was disputed since 2015 though, attributing the planetary signal to the frequency-domain alias of the star magnetic activity cycle, although the existence of another planet on the 198-day orbit is suspected.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (disputed[11]) | 32[17] M🜨 | 1.0376±0.0189 | 407.15±4.2857 | 0.27±0.17 | — | — |
| Disk | 102 AU | — | — | |||