Zeta2 Lyrae

Zeta2 Lyrae is a single,[10] white-hued star in the northern constellation of Lyra. It is a dim star that is just visible to the naked eye with an apparent visual magnitude of 5.74[2] An annual parallax shift of 20.6 mas as seen from Earth provides a distance estimate of about 158 light years from the Sun. It is moving closer to the Sun with a radial velocity of −25 km/s.[5]

For other stars with this Bayer designation, see ζ Lyrae.
Zeta2 Lyrae
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra
Right ascension 18h 44m 48.200240s[1]
Declination +37° 35′ 40.5566″[1]
Apparent magnitude (V) 5.74[2]
Characteristics
Spectral type F0 IVn[3] or F1Vnn[4]
U−B color index +0.06[2]
B−V color index +0.29[2]
Astrometry
Radial velocity (Rv)−25.0±3.7[5] km/s
Proper motion (μ) RA: +23.159[1] mas/yr
Dec.: +23.592[1] mas/yr
Parallax (π)20.6121 ± 0.0576[1] mas
Distance158.2 ± 0.4 ly
(48.5 ± 0.1 pc)
Absolute magnitude (MV)+2.34[6]
Details
Mass1.74[7] M☉
Radius2.05±0.08[1] R☉
Luminosity9.614+0.036
−0.037[1] L☉
Surface gravity (log g)3.94[7] cgs
Temperature7,100+134
−37[1] K
Rotational velocity (v sin i)212[8] km/s
Age1.223[7] Gyr
Other designations
ζ2 Lyr, 7 Lyr, BD+37° 3223, GC 25678, HD 173649, HIP 91973, HR 7057, SAO 67324, WDS J18448+3736D[9]
Database references
SIMBADdata

This star has a stellar classification of F0 IVn,[3] suggesting it is an F-type subgiant star that is evolving away from the main sequence as its supply of hydrogen at the core has been consumed. The n suffix indicates "nebulous" lines caused by its rotation. It is spinning rapidly with a projected rotational velocity of 212 km/s.[8] This is giving the star an oblate shape with an equatorial bulge that is an estimated 29% larger than the polar radius.[11] The star is radiating approximately 9.6 times the Sun's luminosity from the photosphere at an effective temperature of 7,000 K.[1] It has 1.7[7] times the mass of the Sun, twice the Sun's radius,[1] and is about 1.2[7] billion years old.

It is a suspected variable.[9]

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. Deutschman, W. A.; et al. (February 1976), "The galactic distribution of interstellar absorption as determined from the Celescope catalog of ultraviolet stellar observations and a new catalogue of UBV, Hbeta photoelectric observations", Astrophysical Journal Supplement Series, 30: 97–225, Bibcode:1976ApJS...30...97D, doi:10.1086/190359.
  3. 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
  4. Gray, R. O.; Napier, M. G.; Winkler, L. I. (2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal, 121 (4): 2148, Bibcode:2001AJ....121.2148G, doi:10.1086/319956.
  5. Kharchenko, N. V.; et al. (2007), "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations", Astronomische Nachrichten, 328 (9): 889–896, arXiv:0705.0878, Bibcode:2007AN....328..889K, doi:10.1002/asna.200710776.
  6. 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.
  7. 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. Vizier catalog entry
  8. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224.
  9. "zet02 Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 July 2015.
  10. De Rosa, R. J.; et al. (2014). "The VAST Survey - III. The multiplicity of A-type stars within 75 pc". Monthly Notices of the Royal Astronomical Society. 437 (2): 1216. arXiv:1311.7141. Bibcode:2014MNRAS.437.1216D. doi:10.1093/mnras/stt1932.
  11. Belle, G. T. (2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20: 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2.
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