Lambda Virginis

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λ Virginis
Virgo IAU.svg
Cercle rouge 100%.svg
Location of λ Virginis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Virgo
Right ascension 14h 19m 06.59235s[1]
Declination −13° 22′ 15.9459″[1]
Apparent magnitude (V) +4.52[2] (5.00 + 5.63)[3]
Characteristics
Spectral type A1 V[4] (A1V + A1V)[3]
U−B color index +0.12[2]
B−V color index +0.12[2]
Astrometry
Radial velocity (Rv) −10.9[5] km/s
Proper motion (μ) RA: −15.91[1] mas/yr
Dec.: +28.92[1] mas/yr
Parallax (π) 18.81 ± 0.10[3] mas
Distance 173.4 ± 0.9 ly
(53.2 ± 0.3 pc)
Absolute magnitude (MV) +0.73[6]
Orbit[3]
Period (P) 206.7321±0.0040 d
Semi-major axis (a) 19.759±0.079 mas
Eccentricity (e) 0.0610±0.0036
Inclination (i) 109.86±0.24°
Longitude of the node (Ω) 196.40±0.22°
Periastron epoch (T) 53,070.30±0.32
Argument of periastron (ω)
(secondary)
272.28±0.46°
Semi-amplitude (K1)
(primary)
24.78±0.17 km/s
Semi-amplitude (K2)
(secondary)
27.308±0.067 km/s
Details
λ Vir A
Mass 1.897[3] M
Radius 2.35[3] R
Luminosity 20.84±0.25[3] L
Surface gravity (log g) 3.97[3] cgs
Temperature 8,280±200[7] K
Metallicity [Fe/H] 0.0097[3] dex
Rotational velocity (v sin i) 36±1[3] km/s
Age 935[3] Myr
λ Vir B
Mass 1.721[3] M
Radius 1.84[3] R
Luminosity 12.58±0.16[3] L
Surface gravity (log g) 4.14[3] cgs
Temperature 8,280±200[7] K
Rotational velocity (v sin i) 10±2[3] km/s
Other designations
Khambalia, 100 Virginis, λ Vir, BD−12° 4018, FK5 1371, HD 125337, HIP 69974, HR 5359, SAO 158489.[8]
Database references
SIMBAD data

Lambda Virginis (λ Virginis, abbreviated Lam Vir, λ Vir) is a binary star system in the zodiac constellation of Virgo. With an apparent visual magnitude of 4.5, it is bright enough to be seen with the naked eye. Based upon parallax measurements, the system is about 173 light-years away from the Sun. Its two components are designated Lambda Virginis A (also named Khambalia[9]) and B.

Nomenclature[edit]

λ Virginis (Latinised to Lambda Virginis) is the system's Bayer designation. The designations of the two components as Lambda Virginis A and B derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[10]

The system bore the traditional name Khambalia (meaning crooked-clawed) in the culture of the Copts;[11] in 2016, the IAU organized a Working Group on Star Names (WGSN)[12] to catalog and standardize proper names for stars. The WGSN approved the name Khambalia for the component Lambda Virginis A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[9]

In China, 亢宿 (Kàng Xiù), meaning Neck, refers to an asterism consisting of this system, Kappa Virginis, Iota Virginis and Phi Virginis.[13] Consequently, Lambda Virginis itself is known as 亢宿四 (Kàngsusì, English: the Fourth Star of Neck.)

Properties[edit]

Lambda Virginis is a double-lined spectroscopic binary[14] with an orbital period of 206.7 days and an eccentricity of 0.0610. The semi-major axis has an angular size of 0.02 arcseconds, which, at the distance of this system, is equivalent to a physical span of 1.050±0.007 AU. The orbit is inclined by an angle of 110° to the line of sight from the Earth. Tidal theory predicts that eventually the orbit of the stars will circularize and their rotation rates will become synchronized with their orbital motion. However, this will occur over a time scale of more than 1.2 billion years, whereas their estimated age is 935 million years.[3]

The combined spectra of the two components has a stellar classification of A1V,[4] which matches an A-type main-sequence star, they have magnitudes of +5.0 and +5.6.[3] Both components are Am stars,[14] indicating they appear chemically peculiar, the primary appears to be rotating around 3.5 times faster than the secondary.[3]

References[edit]

  1. ^ a b c d van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ a b c d e f g h i j k l m n o p q r s Zhao, M.; et al. (April 2007), "Physical Orbit for λ Virginis and a Test of Stellar Evolution Models", The Astrophysical Journal, 659 (1): 626–641, arXiv:astro-ph/0612135Freely accessible, Bibcode:2007ApJ...659..626Z, doi:10.1086/511415. 
  4. ^ a b Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, 4, Bibcode:1988MSS...C04....0H. 
  5. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W. 
  6. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  7. ^ a b Abt, Helmut A.; Morrell, Nidia I. (July 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. 
  8. ^ "* lam Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-08. 
  9. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017. 
  10. ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707Freely accessible [astro-ph.SR]. 
  11. ^ Allen, Richard Hinckley (1963) [1899]. Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 472. ISBN 0-486-21079-0. 
  12. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016. 
  13. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 28 日
  14. ^ a b Monnier, J. D.; et al. (February 2004), "First Results with the IOTA3 Imaging Interferometer: The Spectroscopic Binaries λ Virginis and WR 140", The Astrophysical Journal, 602 (1): L57–L60, arXiv:astro-ph/0401268Freely accessible, Bibcode:2004ApJ...602L..57M, doi:10.1086/382213.