Theta Lyrae
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| 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 / 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 / 0.0 / ? mas/yr Dec.: 1.23 / 14.0 / ? mas/yr |
| Parallax (π) | 4.24 ± 0.49 mas |
| Distance | approx. 770 ly (approx. 240 pc) |
| Details | |
| Radius | 57 ± 7[4] R☉ |
| 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.[1]
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.[2] BD+37° 3399B is an 11th magnitude star of an unknown spectral type.[3]
[edit] References
- ^ a b "Simbad Query Result". Simbad. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%402924945&Name=*%20tet%20Lyr. Retrieved October 15, 2007.
- ^ a b "Simbad Query Result". Simbad. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%402924947&Name=BD%2b37%20%203399. Retrieved October 15, 2007.
- ^ a b "Simbad Query Result". Simbad. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%402924946&Name=BD%2b37%20%203398B. Retrieved October 15, 2007.
- ^ 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
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