V752 Centauri

V752 Centauri (HD 101799) is multiple star system[10] and variable star in the constellation of Centaurus. An eclipsing binary, its apparent magnitude has a maximum of 9.10, dimming to 9.66 during primary eclipse and 9.61 during secondary eclipse.[2] Its variability was discovered by Howard Bond in 1970.[11] From parallax measurements by the Gaia spacecraft, the system is located at a distance of 410 light-years (125.6 parsecs) from Earth.[1]

V752 Centauri
Observation data
Epoch J2000      Equinox J2000
Constellation Centaurus
Right ascension 11h 42m 48.08s[1]
Declination −35° 48′ 57.50″[1]
Apparent magnitude (V) 9.10 – 9.66[2]
Characteristics
Evolutionary stage F7/G0(V)[3]
Variable type W UMa[4]
Astrometry
Proper motion (μ) RA: -52.175[1] mas/yr
Dec.: -24.364[1] mas/yr
Parallax (π)7.9641 ± 0.0495[1] mas
Distance410 ± 3 ly
(125.6 ± 0.8 pc)
Absolute magnitude (MV)4.00 ± 0.34[5]
Orbit
Period (P)0.37023198 days[6]
Semi-major axis (a)2.59 ± 0.05 R☉[6]
Inclination (i)82.07 ± 0.06[6]°
Semi-amplitude (K1)
(primary)		83.2±5.7[7] km/s
Semi-amplitude (K2)
(secondary)		267.2±6.9[7] km/s
Details
Age3.84[8] Gyr
Primary
Mass1.31 ± 0.07[6] M☉
Radius1.30 ± 0.02[6] R☉
Luminosity2.00 ± 0.07}[6] L☉
Temperature5,955 ± 77[4] K
Secondary
Mass0.39 ± 0.02[6] M☉
Radius0.77 ± 0.01[6] R☉
Luminosity0.75 ± 0.03[6] L☉
Temperature6,221 ± 81[4] K
Other designations
V752 Cen, CD−35°7392, HD 101799, HIP 57129, SAO 202729[9]
Database references
SIMBADdata

V752 Centauri is a contact binary of the W Ursae Majoris type, composed of two F-type stars with a combined spectral type of F7/G0(V).[3] Individually, the components have been classified as F8 + F5,[7] and F8 + F7.5.[12] With effective temperatures of 5,955 and 6,221 K,[4] the system is classified as a W Ursae Majoris variable of subtype W, where the secondary star is hotter than the primary; for this reason, the primary eclipses are caused by the occultation of the secondary star.[7][4] The system has an orbital period of only 0.3702 days and a separation of 2.59 solar radii. The orbit is inclined by 82° in relation to the plane of the sky.[6]

The combination of photometric and spectroscopic data have allowed the direct determination of the parameters of the stars. The primary component has a mass of 1.31 times the solar mass, radius of 1.30 times the solar radius and a luminosity double that of the Sun. The secondary has only 0.39 times the solar mass, 0.77 times the solar radius, and 0.75 times the solar luminosity.[6] Since the stars are in contact, there is considerable mass transfer from the secondary to the primary. It is estimated that the secondary star was initially the more massive star, with 1.76 times the solar mass, while the primary had an initial mass of 0.84 time the solar mass.[8] The system's age is estimated at 3.8 billion years.[8] All contact binary stars are expected to eventually merge into a single, fast-rotating star.[13]

The system's spectrum shows the spectral lines of a third star, which seems to be a K-type main sequence star. This third star is itself a spectroscopic binary with a period of 5.147 days, with a small companion that is probably an M-type red dwarf. The V752 Centauri system is thus composed of four stars, with two binary pairs that orbit each other.[10] Most contact binary stars have one or more distant companions, and were possibly formed by angular momentum loss due to gravitational interactions with these companion stars.[14][6]

The light curve analysis of V752 Centauri reveals that between 1970 and 2000, the orbital period of the eclipsing binary remained approximately constant, indicating there was no significant mass transfer. Around the year 2000, the period abruptly increased, possibly accompanied by a slightly dimmer primary eclipse.[15] Since then, the period has been increasing at a rate of 0.044 seconds per year, which is caused by mass transfer from the less massive star to the more massive one at a rate of 2.52×10−7 M☉ per year. This period change and the beginning of the mass transfer phase were possibly caused by interactions with the companion binary star.[6]

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. Avvakumova, E. A.; Malkov, O. Yu.; Kniazev, A. Yu. (2013). "Eclipsing variables: Catalogue and classification". Astronomische Nachrichten. 334 (8): 860. Bibcode:2013AN....334..860A. doi:10.1002/asna.201311942. hdl:10995/27061.
  3. Houk, Nancy (1982), "Michigan catalogue of two-dimensional spectral types for the HD stars", Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, 3, Bibcode:1982mcts.book.....H
  4. Barone, F.; Di Fiore, L.; Milano, L.; Russo, G. (1993). "Analysis of Contact Binary Systems: AA Ursae Majoris, V752 Centauri, AO Camelopardalis, and V677 Centauri". The Astrophysical Journal. 407: 237. Bibcode:1993ApJ...407..237B. doi:10.1086/172509.
  5. Rucinski, S. M.; Duerbeck, H. W. (1997). "Absolute Magnitude Calibration for the W UMa-Type Systems Based on HIPPARCOS Data". Publications of the Astronomical Society of the Pacific. 109: 1340. arXiv:astro-ph/9710214. Bibcode:1997PASP..109.1340R. doi:10.1086/134014.
  6. Zhou, X.; Soonthornthum, B.; Qian, S. -B.; Fernández Lajús, E. (2019). "V752 Cen – a triple-lined spectroscopic contact binary with sudden and continuous period changes". Monthly Notices of the Royal Astronomical Society. 489 (4): 4760. arXiv:1909.06038. Bibcode:2019MNRAS.489.4760Z. doi:10.1093/mnras/stz2508. S2CID 202572782.
  7. Sisteró, R. F.; Castore De Sisteró, M. E. (1974). "Radial velocity curves of HD 101799". The Astronomical Journal. 79: 391. Bibcode:1974AJ.....79..391S. doi:10.1086/111556.
  8. Yildiz (2014). "Origin of W UMa-type contact binaries – age and orbital evolution". Monthly Notices of the Royal Astronomical Society. 437 (1): 185–94. arXiv:1310.5526. Bibcode:2014MNRAS.437..185Y. doi:10.1093/mnras/stt1874. S2CID 119121897.
  9. "V752 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 14 January 2020.
  10. Schumacher, H. (2009). "Analysis of the W UMa-type Eclipsing Binary V752 Centauri". The Eighth Pacific Rim Conference on Stellar Astrophysics: A Tribute to Kam-Ching Leung. 404: 199. Bibcode:2009ASPC..404..199S.
  11. Bond, Howard E. (1970). "Three Eclipsing Binaries Found Spectroscopically". Publications of the Astronomical Society of the Pacific. 82 (489): 1065. Bibcode:1970PASP...82.1065B. doi:10.1086/129004.
  12. Leung, K. -C (1976). "The contact binary HD 101799". Publications of the Astronomical Society of the Pacific. 88: 936. Bibcode:1976PASP...88..936L. doi:10.1086/130049.
  13. Gazeas, K.; Stȩpień, K. (2008). "Angular momentum and mass evolution of contact binaries". Monthly Notices of the Royal Astronomical Society. 390 (4): 1577. arXiv:0803.0212. Bibcode:2008MNRAS.390.1577G. doi:10.1111/j.1365-2966.2008.13844.x. S2CID 14661232.
  14. Pribulla, T.; Rucinski, S. M. (2006). "Contact Binaries with Additional Components. I. The Extant Data". The Astronomical Journal. 131 (6): 2986–3007. arXiv:astro-ph/0601610. Bibcode:2006AJ....131.2986P. doi:10.1086/503871. S2CID 15762240.
  15. Mallama, A.; Pavlov, H. (2015). "Sudden Period Change and Dimming of the Eclipsing Binary V752 Centauri". Journal of the American Association of Variable Star Observers (Jaavso). 43 (1): 38. Bibcode:2015JAVSO..43...38M.
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