Alruba
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Draco |
| Pronunciation | /ælˈruːbə/ |
| Right ascension | 17h 43m 59.17049s |
| Declination | +54° 48′ 06.1637″ |
| Apparent magnitude (V) | 5.76 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | A0V |
| Astrometry | |
| Radial velocity (Rv) | −2.0 km/s |
| Proper motion (μ) | RA: 17.450 mas/yr Dec.: −18.125 mas/yr |
| Parallax (π) | 7.1436±0.0605 mas |
| Distance | 457 ± 4 ly (140 ± 1 pc) |
| Absolute magnitude (MV) | −0.3 |
| Details | |
| Mass | 2.97±0.07 M☉ |
| Luminosity | 146.7+29.6 −24.7 L☉ |
| Surface gravity (log g) | 3.80±0.10 cgs |
| Temperature | 9,226+107 −106 K |
| Metallicity [Fe/H] | −0.40±0.11 dex |
| Rotational velocity (v sin i) | 170 km/s |
| Age | 58 Myr |
| Other designations | |
| Alruba, BD+53°1978, CPD–51°9815, HD 161693, HIP 86782, HR 6618, SAO 30538 | |
| Database references | |
| SIMBAD | data |
Alruba, a name derived from Arabic for "the foal", is a suspected astrometric binary star system in the northern circumpolar constellation of Draco. It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76. Based on parallax measurements obtained during the Gaia mission, it is located at a distance of about 457 light-years (140 parsecs) from the Sun. The system is drifting closer with a radial velocity of −2 km/s.
The visible component is an A-type main-sequence star with a stellar classification of A0 V. It is about 58 million years old with three times the mass of the Sun and has a high rate of spin, showing a projected rotational velocity of 170 km/s. The star is radiating 147 times the luminosity of the Sun from its photosphere at an effective temperature of 9,226 K. The system is a source for X-ray emission, which is most likely coming from the unseen companion.