Astronomy:Theta Lyrae
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 16m 22.0951s[1] |
| Declination | +38° 08′ 01.431″[1] |
| Apparent magnitude (V) | 4.38[2] |
| Characteristics | |
| Spectral type | K0II[3] |
| U−B color index | +1.23[2] |
| B−V color index | +1.26[2] |
| Astrometry | |
| Radial velocity (Rv) | −31.05±0.14[1] km/s |
| Proper motion (μ) | RA: −2.864[1] mas/yr Dec.: 4.114[1] mas/yr |
| Parallax (π) | 4.2005 ± 0.1053[1] 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[3] |
| Details | |
| Radius | 60.31+1.92 −2.99[4] R☉ |
| Luminosity | 1,374±43[4] L☉ |
| Surface gravity (log g) | 1.93[3] cgs |
| Temperature | 4,523±44[4] K |
| Metallicity [Fe/H] | −0.01[3] dex |
| Rotational velocity (v sin i) | 3.6±1.4[3] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Theta Lyrae (θ Lyr), also named Ninnisig,[5] 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.
Ninnisig and Erragal are two ancient Sumerian deities associated with a pair of stars, identified as Theta Lyrae and Eta Lyrae (Aladfar).[7] The IAU Working Group on Star Names adopted the name Ninnisig for this star on 18 June 2026.[5]
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.[8] BD+37° 3399B is an 11th magnitude star of an unknown spectral type.[9]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". Vizier Online Data Catalog 2237. Bibcode: 2002yCat.2237....0D.
- ↑ 3.0 3.1 3.2 3.3 3.4 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. doi:10.1088/0004-6256/135/3/892. Bibcode: 2008AJ....135..892C.
- ↑ 4.0 4.1 4.2 Baines, Ellyn K.; Clark, ((James H., III)); Schmitt, Henrique R.; Stone, Jordan M.; von Braun, Kaspar (2023-12-01). "33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble". The Astronomical Journal 166 (6): 268. doi:10.3847/1538-3881/ad08be. ISSN 0004-6256. Bibcode: 2023AJ....166..268B.
- ↑ 5.0 5.1 5.2 "IAU Catalog of Star Names". https://exopla.net/star-names/modern-iau-star-names/.
- ↑ "* tet Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+tet+Lyr.
- ↑ Hoffmann, Susanne M. "Ninnisig". IAU Working Group on Star Names. https://ase.exopla.net/index.php/Ninnisig.
- ↑ "BD+37 3399". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD%2B37+3399.
- ↑ "Simbad Query Result". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=Simbad+Query+Result.
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