WZ Andromedae

WZ Andromedae (abbreviated to WZ And) is an eclipsing binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 11.6,[3] but drops down to 12.00 during the main eclipse which occurs roughly every 16.7 hours.[2]

WZ Andromedae
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 01h 01m 43.64665s[1]
Declination +38° 05′ 46.48949″[1]
Apparent magnitude (V) 11.6 – 12.0 variable [2][3]
Characteristics
Spectral type F5 + G3 [3]
Apparent magnitude (B) 11.87[4]
Apparent magnitude (V) 11.26[4]
Apparent magnitude (G) 11.2631[1]
Apparent magnitude (J) 10.252[5]
Apparent magnitude (H) 9.930[5]
Apparent magnitude (K) 9.896[5]
B−V color index 0.5729[4]
Variable type EB
Astrometry
Proper motion (μ) RA: 14.260±0.072 [1] mas/yr
Dec.: −0.723±0.079[1] mas/yr
Parallax (π)1.8634 ± 0.0520[1] mas
Distance1,750 ± 50 ly
(540 ± 10 pc)
Orbit[3]
Period (P)0.6956612±0.0000001 yr
Periastron epoch (T)2446025.734±0.002
Details
Mass2.27[3][lower-alpha 1] M☉
Other designations
2MASS J01014364+3805464, TYC 2799-1250-1
Database references
SIMBADdata

Variability

This binary star was found variable by Henrietta Leavitt, and shows the usual two eclipses, a main one and a secondary one with a less pronounced drop in magnitude. The period of 16.7 days, however, was found to vary in time without any consolidated trend.[3]

System

In an eclipsing binary system, the 16.7 days period is also the orbital period. The two stars are of spectral type F5 and G3, and they have almost the same mass. They could be so close that mass transfer is occurring in the system, changing the orbital period in time. An alternative explanation could be the presence in the system of two low mass companions with orbital periods of 50 and 70 years, respectively. Their contribution to the luminosity of the system, however, would be negligible (less than 1%), but they would have a large angular separation (45 and 72 mas) from the two main stars.[3]

Notes
  1. Total mass of the two main components

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. WZ And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-17.
  3. Zasche, P.; Liakos, A.; Niarchos, P.; Wolf, M.; Manimanis, V.; Gazeas, K. (February 2009). "Period changes in six contact binaries: WZ And, V803 Aql, DF Hya, PY Lyr, FZ Ori, and AH Tau". New Astronomy. 14 (2): 121–128. arXiv:0811.0640. Bibcode:2009NewA...14..121Z. doi:10.1016/j.newast.2008.06.002. S2CID 14302260.
  4. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy & Astrophysics, 355: L27–L30, Bibcode:2000A&A...355L..27H.
  5. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; et al. (June 2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues (2246): II/246. Bibcode:2003yCat.2246....0C.
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