HD 4308
Star in the constellation Tucana
From Wikipedia, the free encyclopedia
HD 4308 is a single[3] star with a planetary system in the southern constellation of Tucana.[10] It has a yellow hue and is a challenge to view with the naked eye even under good seeing conditions, having an apparent visual magnitude of 6.54.[3] This object is located at a distance of 72 light-years, as determined from parallax measurements. It is a population II star[3] and is considered to be a member of the thick disk.[11] The star is receding from the Sun with a radial velocity of +95 km/s.[7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Tucana[1] |
| Right ascension | 00h 44m 39.26721s[2] |
| Declination | −65° 38′ 58.2777″[2] |
| Apparent magnitude (V) | 6.544±0.005[3] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | G6VFe-0.9[4] |
| Apparent magnitude (B) | 7.193[5] |
| Apparent magnitude (V) | 6.552[5] |
| Apparent magnitude (J) | 5.366±0.024[6] |
| Apparent magnitude (H) | 5.101±0.016[6] |
| Apparent magnitude (K) | 4.945±0.020[6] |
| Astrometry | |
| Radial velocity (Rv) | +95.251±0.0162[7] km/s |
| Proper motion (μ) | RA: +157.639 mas/yr[2] Dec.: −741.913 mas/yr[2] |
| Parallax (π) | 45.3559±0.0178 mas[2] |
| Distance | 71.91 ± 0.03 ly (22.048 ± 0.009 pc) |
| Absolute magnitude (MV) | 4.83[1] |
| Details[8] | |
| Mass | 0.95±0.05 M☉ |
| Radius | 1.04±0.03 R☉ |
| Luminosity | 1.03±0.01 L☉ |
| Surface gravity (log g) | 4.38±0.02 cgs |
| Temperature | 5,714±61 K |
| Metallicity [Fe/H] | −0.35±0.07[3] dex |
| Rotational velocity (v sin i) | 1.0±1.0[3] km/s |
| Age | 10.0+0.5 −1.0[9] Gyr |
| Other designations | |
| CD−66°38, GC 897, GJ 31.5, GJ 9028, HD 4308, HIP 3497, SAO 248244, PPM 352003, LFT 71, LHS 1139, LPM 40, LTT 416, TYC 8847-598-1, GCRV 50662, 2MASS J00443925-6538581[10] | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
| ARICNS | data |
Stellar properties
This is a Sun-like G-type main-sequence star with a stellar classification of G6VFe-0.9,[4] where the suffix notation indicates an underabundance of iron in the spectrum. The age of the star is poorly constrained, with estimated ranging from 1.6[8] billion years up to 10 billion.[9] It has 95% of the mass of the Sun but 104% of the Sun's radius. The star is radiating nearly the same luminosity as the Sun from its photosphere at an effective temperature of 5,714 K.[8]
Planetary system
In 2005, a low-mass exoplanet was found in orbit around this star using the radial velocity method with the HARPS spectrograph. It is following a circular orbit close to its host star with a period of just 15.6 days. Unusual for a star with planets, HD 4308 has a metallicity lower than that of the Sun.[12] Further radial velocity observations allowed two additional planets to be detected by 2025.[13]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥0.0442 MJ | 0.115 | 15.56±0.02 | 0.00±0.01 | — | — |
| c | ≥0.15±0.07 MJ | — | 850±25 | 0.47±0.34 | — | — |
| d | ≥0.14±0.08 MJ | — | 1,500±60 | 0.37±0.30 | — | — |