Beta Boötis
A star chart showing the position of β Boötis (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 15h 01m 56.7623s |
| Declination | +40° 23′ 26.047″ |
| Apparent magnitude (V) | 3.488 |
| Characteristics | |
| Evolutionary stage | Yellow giant |
| Spectral type | G8IIIa Fe-0.5 |
| U−B color index | +0.75 |
| B−V color index | +0.94 |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | −18.35±0.21 km/s |
| Proper motion (μ) | RA: −40.708 mas/yr Dec.: −30.168 mas/yr |
| Parallax (π) | 13.878±0.131 mas |
| Distance | 235 ± 2 ly (72.1 ± 0.7 pc) |
| Absolute magnitude (MV) | −0.70 |
| Details | |
| Mass | 3.23±0.07 M☉ |
| Radius | 18.44±0.19 R☉ |
| Luminosity | 188±10 L☉ |
| Surface gravity (log g) | 2.45±0.03 cgs |
| Temperature | 4,997 K |
| Metallicity [Fe/H] | –0.086 dex |
| Rotation | 200±10 days |
| Rotational velocity (v sin i) | 4.1±1.0 km/s |
| Age | 320±20 Myr |
| Other designations | |
| Nakkar, Nekkar, Merez, Meres, Merets, Beta Boo, β Boo, 42 Boötis, BD+40°2840, FK5 555, GC 20226, HD 133208, HIP 73555, HR 5602, SAO 45337 | |
| Database references | |
| SIMBAD | data |
Beta Boötis is a star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from β Boötis, and abbreviated Beta Boo or β Boo. The star has the official name Nekkar, pronounced /ˈnɛkɑːr/, which is derived from an Arabic name for 'the Herdsman'. It has an apparent visual magnitude of 3.5, making it visible to the naked eye and one of the brighter members of the constellation. In the modern constellation, it marks the head of Boötes the herdsman. Based upon parallax measurements obtained by the Gaia spacecraft, this star is approximately 235 light-years (72 parsecs) from the Sun. It is drawing closer to the Sun with a radial velocity of −18 km/s. The magnitude of the star is reduced by 0.06 from extinction caused by intervening gas and dust.