Iota Lyrae

ι Lyrae, Latinised as Iota Lyrae, is a binary star[2] in the northern constellation of Lyra. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude that fluctuates around 5.22.[2] This object is located approximately 950 light years distant from the Sun based on parallax, but is drifting nearer with a radial velocity of −26 km/s.[5]

Iota Lyrae
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lyra
Right ascension 19h 07m 18.13251s[1]
Declination +36° 06′ 00.5592″[1]
Apparent magnitude (V) 5.22[2]
Characteristics
Spectral type B6IV[3]
Variable type Be star[4]
Astrometry
Radial velocity (Rv)−26.0±4.6[5] km/s
Proper motion (μ) RA: −1.04±0.16[6] mas/yr
Dec.: −4.29±0.20[6] mas/yr
Parallax (π)3.5858 ± 0.1924[1] mas
Distance910 ± 50 ly
(280 ± 10 pc)
Absolute magnitude (MV)−1.94[7]
Orbit[8]
Period (P)216.93 yr
Semi-major axis (a)0.172″
Eccentricity (e)0.637
Inclination (i)145.5°
Longitude of the node (Ω)171.4°
Periastron epoch (T)B 1997.28
Argument of periastron (ω)
(secondary)		201.2°
Details
Mass5.02±0.09[9] M☉
Luminosity1,349+175
−155[9] L☉
Temperature13,428+124
−123[9] K
Rotational velocity (v sin i)224[9] km/s
Other designations
ι Lyr, 18 Lyr, BD+35°3485, GC 26338, HD 178475, HIP 93903, HR 7262, SAO 67834, WDS 19073+3606, GSC 02652-01709[10]
Database references
SIMBADdata

This is a wide binary system with a computed orbital period of 217 years and an eccentricity of 0.6.[8] The primary component has a stellar classification of B6IV,[3] matching a B-type subgiant star. It is a Be star,[11] displaying emission lines in its spectrum, and is spinning rapidly with a projected rotational velocity of 224 km/s.[9] The star ranges in brightness from magnitude 5.20 down to 5.27.[4] It has five[9] times the mass of the Sun and is radiating 1,349[9] times the Sun's luminosity from its photosphere at an effective temperature of 13,428 K.[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. 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.
  3. Lesh, Janet Rountree (December 1968). "The Kinematics of the Gould Belt: an Expanding Group?". Astrophysical Journal Supplement. 17: 371. Bibcode:1968ApJS...17..371L. doi:10.1086/190179.
  4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S.
  5. Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  7. 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.
  8. "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 15 March 2017.
  9. 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.
  10. "iot Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-04.
  11. Abt, H. A.; Cardona, O. (October 1984), "Be stars in binaries", Astrophysical Journal, 285: 190–194, Bibcode:1984ApJ...285..190A, doi:10.1086/162490
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