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AH Virginis

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Star in the constellation Virgo
AH Virginis

A visual band light curve for AH Virginis, plotted from INTEGRAL-OMC data
Observation data
Epoch J2000      Equinox J2000
Constellation Virgo
Right ascension 12 14 20.996
Declination +11° 49′ 09.39″
Apparent magnitude (V) 9.18
Characteristics
Spectral type G8V
B−V color index 0.81±0.25
Variable type Eclipsing W UMa
Astrometry
Radial velocity (Rv)6.6±0.9 km/s
Proper motion (μ) RA: 47.828 mas/yr
Dec.: −107.737 mas/yr
Parallax (π)9.6552 ± 0.0203 mas
Distance337.8 ± 0.7 ly
(103.6 ± 0.2 pc)
Absolute magnitude (MV)4.25±0.16
Absolute bolometric
magnitude (Mbol)		4.07±0.16
Orbit
Period (P)0.4075 d
Semi-major axis (a)2.796±0.017 R☉
Eccentricity (e)0.0 (assumed)
Inclination (i)85.2±1.2°
Periastron epoch (T)2,448,765 JD
Argument of periastron (ω)
(secondary)		0.0°
Semi-amplitude (K1)
(primary)		79.6±1.6 km/s
Semi-amplitude (K2)
(secondary)		263.5±1.9 km/s
Details
Primary
Mass1.360 M☉
Radius1.397 R☉
Luminosity1.860 L☉
Temperature5,300 K
Age4.622 Gyr
Secondary
Mass0.412 M☉
Radius0.826 R☉
Luminosity0.634 L☉
Temperature5,671 K
Other designations
AH Vir, BD+12°2437A, HD 106400A, HIP 59683A, SAO 100003A, WDS 12143+1149A
Database references
SIMBADdata

AH Virginis is a contact binary star system in the equatorial constellation of Virgo, abbreviated AH Vir. It is a variable star with a brightness that peaks at an apparent visual magnitude of 9.18, making it too faint to be viewed with the naked eye. The distance to this system is approximately 338 light years based on parallax measurements, and it is drifting further away with a mean radial velocity of 7 km/s. O. J. Eggen in 1969 included this system as a probable member of the Wolf 630 group of co-moving stars.

In 1905, this source was identified as an optical double star by W. J. Hussey, with the pair showing an angular separation of 1.27″ along a position angle of 15.2°. Gaia Data Release 3 astrometry for the companion is flagged as potentially unreliable but shows a similar parallax and proper motion to AH Virginis.

The brighter visual component was found to be variable by P. Guthnick and R. Prager in 1929, and designated AH Vir. This component was determined to be a W Ursae Majoris variable, and an orbital period of 9.78 hours was found by F. Lause in 1934–1935. Y. C. Chang computed orbital elements of this close binary in 1948 and found the system is eclipsing.

In 1960, L. Binnendijk interpreted the particular shape of the light curve for AH Vir as being due to a sub-luminous region on the primary. Multiple observers noted frequent changes to the light curve and period over time, and in 1977 G. A. Bakos found emission in the calcium K line that suggested mass transfer is taking place. The amplitude of these changes compared to the overall brightness variation is among the largest known among W UMa-type variables. The primary eclipse is total with a duration of around 43 minutes. It was proposed in 1991 that the observed variations in the light curve may be caused by magnetic activity and magnetic interactions between the components.

There has been uncertainty as to whether the two stars are in direct contact with each other, or if the system is semi-detached with only the primary being close to its Roche lobe. The evidence now suggests that they are an overcontact system. The orbital period is showing a increase over time of (2.1869±0.0161)×10 d·yr, combined with a cyclical variation with a period of 37.19 years. The system shows a strong level of magnetic activity, with the primary being the more active component. The mean magnetic field strength of the primary is estimated as 1.487 kG. The cyclical variation in orbital period may be related to the activity on the primary.

References

  1. "OMC Archive", OMC Archive, The Astronomical Data Centre at CAB, retrieved 19 December 2021.
  2. ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. ^ 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.
  4. ^ Lu, W. -X.; Rucinski, S. M. (July 1993), "Spectral-Line Broadening Functions of W UMa-Type Binaries. II. AH Vir", Astronomical Journal, 106: 361, Bibcode:1993AJ....106..361L, doi:10.1086/116645.
  5. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  6. ^ Bilir, S.; et al. (2005), "Kinematics of W Ursae Majoris type binaries and evidence of the two types of formation", Monthly Notices of the Royal Astronomical Society, 357 (2): 497–517, arXiv:astro-ph/0411291, Bibcode:2005MNRAS.357..497B, doi:10.1111/j.1365-2966.2005.08609.x, S2CID 16274339.
  7. ^ Latković, Olivera; et al. (2021), "Statistics of 700 Individually Studied W UMa Stars", The Astrophysical Journal Supplement Series, 254 (1): 10, arXiv:2103.06693, Bibcode:2021ApJS..254...10L, doi:10.3847/1538-4365/abeb23, S2CID 232185576.
  8. "AH Vir". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-09-09.
  9. Eggen, Olin J. (October 1969), "Stellar Groups in the Old Disk Population", Publications of the Astronomical Society of the Pacific, 81 (482): 553, Bibcode:1969PASP...81..553E, doi:10.1086/128823, S2CID 122212885.
  10. Hussey, William Joseph (1905), "Observations of one hundred new double stars : eleventh catalogue", Lick Observatory Bulletin, 81, Berkeley: The University Press: 151–158, Bibcode:1905LicOB...3..151H, doi:10.5479/ADS/bib/1905LicOB.3.151H. Identified as HU 1137.
  11. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  12. Guthnick, P.; Prager, R. (December 1929), "Benennung von veränderlichen Sternen", Astronomische Nachrichten (in German), 237 (10): 169, Bibcode:1929AN....237..169G, doi:10.1002/asna.19292371002.
  13. Lause, Friedrich (December 1935), "Beobachtungen von Bedeckungsveräderlichen V", Astronomische Nachrichten, 257 (13): 211–214, Bibcode:1935AN....257..211L, doi:10.1002/asna.19352571304.
  14. Chang, Y. C. (January 1948), "Spectrographic Observations of the Eclipsing Binaries of the W Ursae Majoris Type: AH Virginis and TZ Bootis", Astrophysical Journal, 107: 96, Bibcode:1948ApJ...107...96C, doi:10.1086/144990.
  15. Binnendijk, L. (August 1960), "The light variation and orbital elements of AH Virginis", Astronomical Journal, 65: 358–373, Bibcode:1960AJ.....65..358B, doi:10.1086/108270.
  16. Bakos, G. A. (1977), "Variations of the Light Curve and the Period of AH VIR", Bulletin of the Astronomical Institute of Czechoslovakia, vol. 28, p. 157, Bibcode:1977BAICz..28..157B.
  17. Kaluzny, J. (1984), "Determination of parameters of W UMa-type systems : V757 Cen, GW Cep, BX Peg, AH Vir", Acta Astronautica, 34: 217–224, Bibcode:1984AcA....34..217K.
  18. Demircan, O.; et al. (January 1991), "A Period Analysis of AH Virginis", Astronomical Journal, 101: 201, Bibcode:1991AJ....101..201D, doi:10.1086/115679.
  19. ^ Chen, Ming; Xiang, Fu-Yuan; Yu, Yun-Xia; Xiao, Ting-Yu (February 2015), "The orbital period variations of AH Virginis", Research in Astronomy and Astrophysics, 15 (2): 275–280, Bibcode:2015RAA....15..275C, doi:10.1088/1674-4527/15/2/010, S2CID 121701577, 275-280.

Further reading

  • Demircan, Osman (July 1987), "BV Observations of W-Ursae Type Binaries - CK-Bootis, BI-Canum, and AH-Virginis", Astrophysics and Space Science, 135 (1): 169–174, Bibcode:1987Ap&SS.135..169D, doi:10.1007/BF00644471, S2CID 119406541.
  • Niarchos, P. G. (July 1983), "Light curves and elements of AH Virginis", Astronomy and Astrophysics Supplement Series, 53: 13–19, Bibcode:1983A&AS...53...13N.
  • Hoffmann, M. (March 1981), "B and Mg Band Observations of AH Vir in 1977", Information Bulletin on Variable Stars, 1933: 1, Bibcode:1981IBVS.1933....1H.
  • Hopp, U.; Witzigmann, S. (August 1981), "Note on the Period of the W UMa Star AH Vir", Information Bulletin on Variable Stars, 2005: 1, Bibcode:1981IBVS.2005....1H.
  • Landolt, Arlo U. (June 1972), "A Time of Minimum for AH Virginis", Publications of the Astronomical Society of the Pacific, 84 (499): 448, Bibcode:1972PASP...84..448L, doi:10.1086/129312, S2CID 122352284.
  • Sievers, J. R. (October 1963), "A Photoelectric Study of AH Virginis", Publications of the Astronomical Society of the Pacific, 75 (446): 446, 418, Bibcode:1963PASP...75..418S, doi:10.1086/127995.
  • Kitamura, M.; et al. (1957), "Photoelectric Observations of AH Virginis and the Interpretation of its Color Changes at Light Minima", Publications of the Astronomical Society of Japan, 9: 119, Bibcode:1957PASJ....9..119K.
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