Theta Lyrae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 16m 22.0951s |
| Declination | +38° 08′ 01.431″ |
| Apparent magnitude (V) | 4.38 |
| Characteristics | |
| Spectral type | K0II |
| U−B color index | +1.23 |
| B−V color index | +1.26 |
| Astrometry | |
| Radial velocity (Rv) | −31.05±0.14 km/s |
| Proper motion (μ) | RA: −2.864 mas/yr Dec.: 4.114 mas/yr |
| Parallax (π) | 4.2005±0.1053 mas |
| Distance | 755.9+21.9 −20.2 ly (237.9+6.7 −6.2 pc) |
| Absolute magnitude (MV) | −2.76+0.27 −0.24 |
| Details | |
| Radius | 60.31+1.92 −2.99 R☉ |
| Luminosity | 1,374±43 L☉ |
| Surface gravity (log g) | 1.93 cgs |
| Temperature | 4,523±44 K |
| Metallicity [Fe/H] | −0.01 dex |
| Rotational velocity (v sin i) | 3.6±1.4 km/s |
| Other designations | |
| θ Lyrae, 21 Lyrae, HR 7314, BD+37°3398, HD 180809, SAO 68065, HIP 94713, GC 26585, IDS 19129+3757, GSC 03121-02287 | |
| Database references | |
| SIMBAD | data |
Theta Lyrae (θ Lyr) is a red giant star in the constellation Lyra, approximately 760 light years away from Earth.
Theta Lyrae is an orange bright giant star of the spectral type K0II, which means that it possesses a surface temperature of about 5,000 K, and is many times bigger and brighter, yet cooler, than the Sun.
BD+37°3399 and BD+37°3399B are respectively 10th- and 11th-magnitude companions, although not at the same distance. BD+37°3399 is a giant star with a spectral type of K2III. It is therefore almost the same temperature as Theta Lyrae. BD+37° 3399B is an 11th magnitude star of an unknown spectral type.