Lambda Lyrae
λ Lyrae, Latinized from Lambda Lyrae, is a suspected binary star[8] system in the northern constellation of Lyra.[7] It is an orange-hued point of light that is dimly visible to the naked eye with an apparent visual magnitude of 4.94.[2] The system is located approximately 1,300 light years distant from the Sun based on parallax, but is drifting closer with a radial velocity of −17.7 km/s.[4]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 00m 00.82534s[1] |
| Declination | +32° 8′ 43.8418″[1] |
| Apparent magnitude (V) | 4.937[2] |
| Characteristics | |
| Spectral type | K2.5III:Ba0.5[3] |
| U−B color index | +1.609[2] |
| B−V color index | +1.455[2] |
| Astrometry | |
| Radial velocity (Rv) | −17.69±0.02[4] km/s |
| Proper motion (μ) | RA: 6.526[1] mas/yr Dec.: 9.765[1] mas/yr |
| Parallax (π) | 2.4502 ± 0.2016[1] mas |
| Distance | 1,300 ± 100 ly (410 ± 30 pc) |
| Absolute magnitude (MV) | −3.75+0.65 −0.50[5] |
| Details | |
| Mass | 6.3±0.8[6] M☉ |
| Radius | 102.11+3.94 −6.78[1] R☉ |
| Luminosity | 3073.1±287.7[1] L☉ |
| Surface gravity (log g) | 2.21[5] cgs |
| Temperature | 4,253+149 −80[1] K |
| Metallicity [Fe/H] | −0.02[5] dex |
| Rotational velocity (v sin i) | 3.2±1.0[5] km/s |
| Age | 58.4±22.6[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
The visible component is an aging giant star with a stellar classification of K2.5III:Ba0.5[3] and an estimated age of around 58[6] million years. The suffix notation indicates this is a mild barium star[9] and hence it may have a white dwarf companion,[8] while the colon indicates there is some uncertainty about the class. Having exhausted the supply of hydrogen at its core, it has cooled and expanded off the main sequence, and now has 102[1] times the radius of the Sun. The star has six[6] times the mass of the Sun and is radiating over 3,000 times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,253 K.[1]
References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society, 172: 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
- Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins Catalog of Revised MK Types for the Cooler Stars", The Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373
- Famaey, B.; et al. (2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430: 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272.
- 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.
- Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410: 190, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
- "Lam Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-17.
- Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
- Lu, Phillip K. (1991), "Taxonomy of barium stars", Astronomical Journal, 101: 2229, Bibcode:1991AJ....101.2229L, doi:10.1086/115845.