HD 30177
Star in the constellation Dorado
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HD 30177 is a single star with a pair of orbiting exoplanets in the southern constellation Dorado. Based on parallax measurements, it is located at a distance of 181 light years from the Sun. It has an absolute magnitude of 4.72,[3] but at that distance the star is too faint to be viewed by the naked eye with an apparent visual magnitude of 8.41.[1] The star is drifting further away with a radial velocity of 62.7 km/s.[5]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Dorado[1] |
| Right ascension | 04h 41m 54.374s[2] |
| Declination | −58° 01′ 14.73″[2] |
| Apparent magnitude (V) | 8.41[1] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | G8V[4] |
| B−V color index | 0.773±0.015[1] |
| Astrometry | |
| Radial velocity (Rv) | 62.697±0.0013[5] km/s |
| Proper motion (μ) | RA: 66.303±0.023 mas/yr[2] Dec.: −11.795±0.024 mas/yr[2] |
| Parallax (π) | 18.0190±0.0195 mas[2] |
| Distance | 181.0 ± 0.2 ly (55.50 ± 0.06 pc) |
| Absolute magnitude (MV) | 4.72±0.09[3] |
| Details[6] | |
| Mass | 1.053±0.023 M☉ |
| Radius | 1.019±0.034 R☉ |
| Luminosity | 1.04±0.01[7] L☉ |
| Surface gravity (log g) | 4.417±0.034 cgs |
| Temperature | 5,680±56[8] K |
| Metallicity [Fe/H] | 0.43±0.04[8] dex |
| Rotation | ~45 d |
| Rotational velocity (v sin i) | 2.96±0.50[9] km/s |
| Age | 3.6+2.5 −2.2[8] Gyr |
| Other designations | |
| CD−58°984, HD 30177, HIP 21850, SAO 233633, 2MASS J04415438-5801146[10] | |
| Database references | |
| SIMBAD | data |
The spectrum of HD 30177 matches a late G-type main-sequence star with a stellar classification of G8V.[4] It is a yellow dwarf with a mass and radius similar to the Sun that is fusing hydrogen in its core. The chromosphere shows a negligible level of magnetic activity.[3] The abundance of iron, an indicator of the star's metallicity, is more than double the Sun's. It is radiating a similar luminosity to the Sun from its photosphere at an effective temperature of 5,607 K.[6]
A 2024 multiplicity survey, using astrometry from the Gaia spacecraft, identified a proper motion companion to HD 30177. This co-moving companion is a red dwarf star, around 10% the mass of the Sun, is located at 780" from HD 30177 with a position angle of 188°. The angular distance translates to an observed separation of 43,300 astronomical units.[11]
Planetary system
The Anglo-Australian Planet Search team announced the discovery of HD 30177 b, which has a minimum mass 8 times that of Jupiter, on June 13, 2002. The scientific paper describing the discovery was published in The Astrophysical Journal in 2003.[12][3] A second massive gas giant planet was later discovered in an approximately 32 year orbit.[13] In 2022, the inclination and estimated mass of both planets were measured via astrometry,[14] figures which were updated in a 2026 publication.[8]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 8.25+1.05 −0.85 MJ |
3.49+0.18 −0.14 |
2,539+1 −3 |
0.186+0.002 −0.004 |
65.5+1.7 −4.2° |
— |
| c | 4.67+0.44 −0.43 MJ |
9.90+0.29 −0.62 |
11,320+490 −940 |
0.21+0.01 −0.02 |
72.7+17.8 −5.8° |
— |