16 Lyrae
16 Lyrae is a suspected astrometric binary[8] star system in the constellation Lyra,[7] located 126 light years away from the Sun based on parallax.[1] It is visible to the naked eye as a dim, white-hued star with a combined apparent visual magnitude of 5.00.[2] The system is moving further away from the Earth with a heliocentric radial velocity of +5 km/s.[2] It is a suspected member of the Ursa Major Moving Group stream.[9]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 19h 01m 26.38228s[1] |
| Declination | +46° 56′ 05.1398″[1] |
| Apparent magnitude (V) | 5.00[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A6 IV[4] or A7 V[5] |
| B−V color index | +0.186±0.005[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.9±0.9[2] km/s |
| Proper motion (μ) | RA: +22.239[1] mas/yr Dec.: −80.409[1] mas/yr |
| Parallax (π) | 25.9005 ± 0.1377 mas[1] |
| Distance | 125.9 ± 0.7 ly (38.6 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.13[2] |
| Details | |
| Mass | 1.80±0.01[3] M☉ |
| Radius | 1.87+0.04 −0.09[1] R☉ |
| Luminosity | 12.043±0.079[1] L☉ |
| Surface gravity (log g) | 4.28[6] cgs |
| Temperature | 7870+191 −93[1] K |
| Rotational velocity (v sin i) | 124[3] km/s |
| Age | 791[6] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Cowley et al. (1969) found a stellar classification of A7 V[5] for the visible component, matching an A-type main-sequence star that is generating energy through hydrogen fusion at its core. Abt and Morrell (1995) instead listed a class of A6 IV,[4] suggesting it has left the main sequence and become a subgiant star. It is 791[6] million years old with a high rate of spin, showing a projected rotational velocity of 124 km/s.[3] This system is a source for X-ray emission with a luminosity of 105.3×1020 W, which is most likely coming from the unseen companion.[10]
References
- ^ a b c d e f g h i 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.
- ^ a b c d e f Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ a b c d Zorec, J.; Royer, F. (2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789, A120.
- ^ a b Abt, Helmut A.; Morrell, Nidia I (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182
- ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
- ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ a b "16 Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-28.
- ^ 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, S2CID 14878976.
- ^ King, Jeremy R.; et al. (2003), "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", The Astronomical Journal, 125 (4): 1980, Bibcode:2003AJ....125.1980K, doi:10.1086/368241
- ^ Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.