Lambda Virginis
Lambda Virginis (λ Virginis, abbreviated Lambda 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 (formally named Khambalia /kæmˈbeɪliə/)[9] and B.
| 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 mas[3] |
| 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 | |
| Database references | |
| SIMBAD | data |
Nomenclature
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 occurs in the lunar station that was given the name χαμβαλια (khambalia)[11] in a Coptic manuscript list of lunar stations, which Crum concluded were either in "debased" Greek or in a few cases Coptic equivalents of Greek names. Given that the Greeks are not known to have used lunar stations, the origin of the names is unknown.[12] Allen's source[13] translates the name as "the crooked-clawed", and identifies it with the Greek word γαμψωλή gampsôlê, which Liddell & Scott identify as a variant of γαμψότης gampsotês "crookedness, of talons". (Coptic has no /ɡ/ sound, and so often substitutes k for g in Greek words, though not usually kh.)
In 2016, the IAU organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[15] It 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.[16] Consequently, Lambda Virginis itself is known as 亢宿四 (Kàngsusì, English: the Fourth Star of Neck.)
Properties
Lambda Virginis is a double-lined spectroscopic binary[17] 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,[17] indicating they appear chemically peculiar. The primary appears to be rotating around 3.5 times faster than the secondary.[3]
References
- ^ a b c d van Leeuwen, F. (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, S2CID 18759600.
- ^ 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.
- ^ 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/0612135, Bibcode:2007ApJ...659..626Z, doi:10.1086/511415, S2CID 13233388.
- ^ a b Houk, N.; Smith-Moore, M. (1988), Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars, vol. 4, Bibcode:1988mcts.book.....H.
- ^ Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
- ^ 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.
- ^ 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.
- ^ "* lam Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-09-08.
- ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
- ^ 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:1012.0707 [astro-ph.SR].
- ^ 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.
- ^ See station 16 in footnote 12 in Stefan Weinstock, "Lunar Mansions and Early Calendars", Journal of Hellenic Studies, Volume 69, November 1949, pp. 48-69.
- ^ p.33 of Robert Brown Jr, "Euphratean Stellar Researches", part V, in the Proceedings of the Society of Biblical Archeology, vol. xviii, no. cxxxiv, 1896 Jan 14, pp.25–44.
- ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
- ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
- ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 28 日
- ^ 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/0401268, Bibcode:2004ApJ...602L..57M, doi:10.1086/382213, S2CID 14580216.