Theta Lyrae
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 16m 22.0951s / 19h 16m 30.069s / 19h 16m 28.7s |
| Declination | +38° 8' 1.431" / +38° 8' 35.80" / +38° 7' 1" |
| Apparent magnitude (V) | 4.347 / 9.5 / 11.0 |
| Characteristics | |
| Spectral type | K0II[1] + K2III + ? |
| U−B color index | +1.23 |
| B−V color index | +1.25 |
| Astrometry | |
| Radial velocity (Rv) | -30.9 km/s |
| Proper motion (μ) | RA: -0.49 mas/yr Dec.: 1.23 / 14.0 mas/yr |
| Parallax (π) | 4.24 ± 0.49 mas |
| Distance | approx. 770 ly (approx. 240 pc) |
| Absolute magnitude (MV) | −2.76+0.27 −0.24[1] |
| Details | |
| θ Lyr | |
| Radius | 57±7[2] R☉ |
| Surface gravity (log g) | 1.93[1] cgs |
| Temperature | 4500[1] K |
| Metallicity [Fe/H] | −0.01[1] dex |
| Rotational velocity (v sin i) | 3.6±1.4[1] km/s |
| Other designations | |
Theta Lyrae (θ Lyr) is a star in a trinary star system, in the constellation Lyra, approximately 770 light years away from Earth. Theta Lyrae is an orange bright giant star of the spectral type K0II, meaning it possesses a surface temperature of about 5,000 kelvins, and is many times bigger and brighter, yet cooler, than our Sun.[3]
It is orbited by a subsystem composed of BD+37° 3399 and BD+37° 3399B. 10th magnitude BD+37° 3399 is a giant star with a spectral type of K2III. It is therefore almost the same temperature as Theta Lyrae, but smaller and dimmer.[4] BD+37° 3399B is an 11th magnitude star of an unknown spectral type.[5]
References
- ^ a b c d e f Carney, Bruce W.; et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal, 135 (3): 892–906, arXiv:0711.4984, Bibcode:2008AJ....135..892C, doi:10.1088/0004-6256/135/3/892
- ^ Nordgren, Tyler E.; et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal, 118 (6): 3032–3038, Bibcode:1999AJ....118.3032N, doi:10.1086/301114
{{citation}}: CS1 maint: multiple names: authors list (link) - ^ a b "Simbad Query Result". Simbad. Retrieved October 15, 2007.
- ^ a b "Simbad Query Result". Simbad. Retrieved October 15, 2007.
- ^ a b "Simbad Query Result". Simbad. Retrieved October 15, 2007.