Astronomy:Delta1 Lyrae

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Short description: Binary star system in the constellation of Lyra


Delta1 Lyrae
Observation data
Equinox J2000.0]] (ICRS)
Constellation Lyra
Right ascension  18h 53m 43.55924s[1]
Declination +36° 58′ 18.1891″[1]
Apparent magnitude (V) 5.56[2]
Characteristics
Spectral type B2.5V[3][4]
U−B color index −0.67[2]
B−V color index −0.15[2]
Astrometry
Radial velocity (Rv)−25.8[5] km/s
Proper motion (μ) RA: +1.350[1] mas/yr
Dec.: −2.985[1] mas/yr
Parallax (π)2.8072 ± 0.1334[1] mas
Distance1,160 ± 60 ly
(360 ± 20 pc)
Absolute magnitude (MV)−1.55[6]
Orbit[7]
Period (P)88.352 days
Semi-major axis (a)≥46.8 Gm (0.313 astronomical unit|AU)
Eccentricity (e)0.37±0.03
Periastron epoch (T)2428406.613±0.500 JD
Argument of periastron (ω)
(secondary)
191.3±0.1°
Semi-amplitude (K1)
(primary)
39.7±1.8 km/s
Details
δ1 Lyr A
Mass7.9±0.1 M[4]
7.75±0.50 M[8]
6.6+0.68
−0.61
[9] M
Luminosity838[6] L
Luminosity (bolometric)3,620[8] L
Surface gravity (log g)3.764±0.032 (3.848 polar)[10] cgs
Temperature20,350[8] K
Metallicity [Fe/H]−0.05[6] dex
Rotational velocity (v sin i)86±10[10] km/s
Age21.1±2.2 Myr[4]
9+9
−4
[9] Myr
Other designations
Delta1 Lyr, 11 Lyrae, NSV 11504, BD+36°3307, GC 25934, HD 175426, HIP 92728, HR 7131, SAO 67537, WDS J18537+3658A, GSC 02650-02146[11]
Database references
SIMBADdata

Delta1 Lyrae, its name Latinized from δ1 Lyrae, is a binary star system in the northern constellation of Lyra. It is dimly visible to the naked eye at night with a combined apparent visual magnitude of 5.56.[2] The system is located at a distance of approximately 1,160 light years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −26 km/s.[5] O. J. Eggen originally included this as a candidate member of the proposed Delta Lyrae cluster.[12]

The variable radial velocity of this star was discovered from photographic plates taken at the Yerkes Observatory in 1904.[13] The first set of orbital elements was computed by Frank Craig Jordan in 1916.[14] It is a single-lined spectroscopic binary with an orbital period of 88.4 days and an eccentricity (ovalness) of 0.37.[7]

The visible component of the pair has a blue-white hue with a stellar classification of B2.5V,[3][4] indicating that it is a B-type main-sequence star undergoing core hydrogen fusion. It is a few million years old with a relatively high rotation rate and around 7–8 times the mass of the Sun. The star is radiating about 3,620[8] times the Sun's luminosity from its photosphere at an effective temperature of 20,350 K.[8]

There is a magnitude 9.93 visual companion at an angular separation of 175.30 arcseconds along a position angle of 20°, as of 2012. This component was discovered by William Herschel.[15] It is an evolved giant star with a class of K2III at a distance of around 1,760 light years.[16]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. 2.0 2.1 2.2 2.3 Guetter, H. H. (October 1974), "UBV photometry of 180 early-type stars", Publications of the Astronomical Society of the Pacific 86: 795–797, doi:10.1086/129675, Bibcode1974PASP...86..795G. 
  3. 3.0 3.1 Guetter, Harry H. (April 1968), "Spectral classification of 239 early-type stars", Publications of the Astronomical Society of the Pacific 80 (473): 197, doi:10.1086/128611, Bibcode1968PASP...80..197G. 
  4. 4.0 4.1 4.2 4.3 Tetzlaff, N. et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, doi:10.1111/j.1365-2966.2010.17434.x, Bibcode2011MNRAS.410..190T. 
  5. 5.0 5.1 Wilson, Ralph Elmer (1953), "General catalogue of stellar radial velocities", Carnegie Institute Washington D.C. Publication (Carnegie Institution of Washington), Bibcode1953GCRV..C......0W. 
  6. 6.0 6.1 6.2 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode2012AstL...38..331A. 
  7. 7.0 7.1 Richardson, E. H.; McKellar, A. (1957), "Redetermination of the spectrographic orbit of delta1 Lyrae", Publ. Dominion Astrophys. Obs. 10: 407–413, Bibcode1958PDAO...10..407R.  , p. 412
  8. 8.0 8.1 8.2 8.3 8.4 Hohle, M. M. et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, doi:10.1002/asna.200911355, Bibcode2010AN....331..349H. 
  9. 9.0 9.1 Gullikson, Kevin et al. (July 26, 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal 152 (2): 40–53, doi:10.3847/0004-6256/152/2/40, Bibcode2016AJ....152...40G. 
  10. 10.0 10.1 Huang, W.; Gies, D. R. (August 2008), "Stellar Rotation in Field and Cluster B Stars", The Astrophysical Journal 683 (2): 1045–1051, doi:10.1086/590106, Bibcode2008ApJ...683.1045H. 
  11. "del01 Lyr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=del01+Lyr. 
  12. Eggen, O. J. (July 1983), "Concentrations in the Local Association- II. The northern concentrations including the alf Per, Pleiades, M 34 and del LYR clusters.", Monthly Notices of the Royal Astronomical Society 204: 391–403, doi:10.1093/mnras/204.2.391, Bibcode1983MNRAS.204..391E. 
  13. Frost, E. B.; Adams, W. S. (1904), "Observations with the Bruce spectrograph", The Astrophysical Journal 19: 352, doi:10.1086/141124, Bibcode1904ApJ....19..350F. 
  14. Jordan, Frank Craig (1916), "The orbit of [delta]1 Lyrae", Publications of the Allegheny Observatory of the University of Pittsburgh 3 (14): 119–124, Bibcode1916PAllO...3..119J. 
  15. Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal 122 (6): 3466–3471, doi:10.1086/323920, Bibcode2001AJ....122.3466M. 
  16. "BD+36 3308". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD%2B36+3308.