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]

16 Lyrae
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]
Distance125.9 ± 0.7 ly
(38.6 ± 0.2 pc)
Absolute magnitude (MV)+2.13[2]
Details
Mass1.80±0.01[3] M☉
Radius1.87+0.04
−0.09[1] R☉
Luminosity12.043±0.079[1] L☉
Surface gravity (log g)4.28[6] cgs
Temperature7870+191
−93[1] K
Rotational velocity (v sin i)124[3] km/s
Age791[6] Myr
Other designations
16 Lyr, NSV 11677, BD+46°2602, HD 177196, HIP 93408, HR 7215, SAO 48011, WDS J19014+4656A, GSC 03545-03041[7]
Database references
SIMBADdata

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
  1. 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.
  2. 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.
  3. 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.
  4. 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
  5. 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.
  6. 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.
  7. "16 Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-05-28.
  8. 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.
  9. 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
  10. 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.
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