36 G. Doradus
Astrometric binary star system in the constellation Dorado
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36 G. Doradus (HD 40409) is a suspected astrometric binary[8] star system in the southern constellation of Dorado. It is a faint system but visible to the naked eye with an apparent visual magnitude of 4.65.[2] Based upon an annual parallax shift of 36.60 mas,[1] it is located 89 light years away from the Sun. It is moving further away with a heliocentric radial velocity of +25 km/s.[2] The system has a relatively high proper motion, traversing the celestial sphere at the rate of 0.57 arcseconds per year along a position angle of 14.51°.[9]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 05h 54m 06.05459s[1] |
| Declination | −63° 05′ 23.2090″[1] |
| Apparent magnitude (V) | 4.65[2] |
| Characteristics | |
| Spectral type | K2 III[3] |
| B−V color index | 1.022±0.045[2] |
| Astrometry | |
| Radial velocity (Rv) | +25.1±0.8[2] km/s |
| Proper motion (μ) | RA: +148.129 mas/yr[1] Dec.: +550.143 mas/yr[1] |
| Parallax (π) | 36.5981±0.0924 mas[1] |
| Distance | 89.1 ± 0.2 ly (27.32 ± 0.07 pc) |
| Absolute magnitude (MV) | 2.56[2] |
| Details[4] | |
| Mass | 1.28±0.03[5] M☉ |
| Radius | 4.76±0.14 R☉ |
| Luminosity | 9.68±0.40[5] L☉ |
| Surface gravity (log g) | 3.020±0.155 cgs |
| Temperature | 4,807±62 K |
| Metallicity [Fe/H] | +0.141±0.035 dex |
| Age | 7.91[6] Gyr |
| Other designations | |
| CD−63°218, FK5 2452, GJ 224.1, GJ 9194, HD 40409, HIP 27890, HR 2102, SAO 249390[7] | |
| Database references | |
| SIMBAD | data |
Based on the stellar classification of K2 III assigned by Gray et al. (2006),[3] the visible component is a K-type giant star. In contrast, Keenan and McNeil (1989) gave it a somewhat less evolved classification of K2 III–IV.[10] It is about eight billion years old[6] with 28% more mass than the Sun,[5] and has expanded to 4.76 times the Sun's radius. The star is radiating 10[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,807 K.[4]