9 Boötis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Boötes |
| Right ascension | 13h 56m 34.18103s |
| Declination | +27° 29′ 31.4932″ |
| Apparent magnitude (V) | 5.02 |
| Characteristics | |
| Evolutionary stage | AGB |
| Spectral type | K3 III |
| B−V color index | 1.441±0.005 |
| Variable type | suspected irregular |
| Astrometry | |
| Radial velocity (Rv) | −41.07±0.14 km/s |
| Proper motion (μ) | RA: +28.154 mas/yr Dec.: −48.279 mas/yr |
| Parallax (π) | 5.2113±0.1011 mas |
| Distance | 630 ± 10 ly (192 ± 4 pc) |
| Absolute magnitude (MV) | −1.23 |
| Details | |
| Mass | 3.5±0.5 M☉ |
| Radius | 44 R☉ |
| Luminosity | 857 L☉ |
| Surface gravity (log g) | 1.85 cgs |
| Temperature | 4,197 K |
| Metallicity [Fe/H] | −0.27 dex |
| Rotational velocity (v sin i) | 1.5 km/s |
| Other designations | |
| 9 Boo, NSV 6502, BD+28°2278, GC 18850, HD 121710, HIP 68103, HR 5247, SAO 83084 | |
| Database references | |
| SIMBAD | data |
9 Boötis is a single, variable star in the northern constellation of Boötes, located around 630 light years away from the Sun. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 5.0. This object is moving closer to the Earth with a heliocentric radial velocity of −41 km/s.
This is an aging giant star with a stellar classification of K3 III, which indicates it has exhausted the hydrogen at its core and evolved of the main sequence. As a consequence, its outer atmosphere has swollen to 44 times the radius of the Sun. It is a suspected irregular variable that ranges in photographic magnitude from 6.1 down to 6.6. 9 Boötis is considered mildly lithium-rich with a moderate level of chromospheric activity. It is radiating 857 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,197 K.