V373 Cassiopeiae

V373 Cas is a binary star system in the northern constellation Cassiopeia. It is a suspected eclipsing binary with an apparent visual magnitude that decreases from a baseline of 6.03 down to 6.13.[3] The system is located at a distance of approximately 6,200 light years from the Sun, but is drifting closer with a radial velocity of around −25.5 km/s.[4]

V373 Cassiopeiae

V373 Cassiopeiae (center) in optical light. The bright yellow star to the upper right of V373 Cas is ρ Cas.
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 23h 55m 33.83878s[1]
Declination +57° 24′ 43.8057″[1]
Apparent magnitude (V) 6.03[2]
Characteristics
Spectral type B0.5II + B4III/V[2]
B−V color index 0.155±0.005[2]
Variable type Eclipsing?[3]
Astrometry
Radial velocity (Rv)−25.5±0.9[4] km/s
Proper motion (μ) RA: −4.098[1] mas/yr
Dec.: −0.101[1] mas/yr
Parallax (π)0.5267 ± 0.0583[1] mas
Distanceapprox. 6,200 ly
(approx. 1,900 pc)
Orbit[5]
Period (P)13.41921 days
Eccentricity (e)0.126±0.019
Periastron epoch (T)2,420,801.98 JD
Argument of periastron (ω)
(secondary)		16±8°
Semi-amplitude (K1)
(primary)		106.7±2.7 km/s
Semi-amplitude (K2)
(secondary)		144.6±2.6 km/s
Details[6]
A
Mass18.6±2.4 M☉
Surface gravity (log g)3.0±0.2 cgs
Temperature23,200±600 K
Rotational velocity (v sin i)130±10 km/s
Age7–8 Myr
B
Mass14.2±1.9 M☉
Surface gravity (log g)3.5±0.2 cgs
Temperature26,800±1,500 K
Rotational velocity (v sin i)60±5 km/s
Other designations
V373 Cas, BD+56°3115, GC 33184, HD 224151, HIP 117957, HR 9052, SAO 35899[7]
Database references
SIMBADdata

The binary nature of this system was announced in 1912 by Walter S. Adams.[8] It is a double-lined spectroscopic binary with an orbital period of 13.4 days and an eccentricity of 0.13.[5] The system was found to be variable in 1958 by C. Roger Lynds, and the variability cycle was shown to be related to the orbital period.[8] It has been described as a heartbeat star rather than an eclipsing system. This is a type of pulsating star where the pulsations are induced by the tidal attraction of a close companion.[9]

V373 Cas is composed of two hot blue-white giant stars that have exhausted their core hydrogen and expanded off the main sequence. Lyubimkov and colleagues analysed spectral and radial velocity to calculate that the stars were ~19 and ~15 times as massive as the Sun and the age of the system is around 7-8 million years old.[6] The primary component is the more evolved and now comes close to filling its Roche lobe when it is at periastron.[10]

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. 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.
  3. 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.
  4. Wilson, R. E. (1953). "General Catalogue of Stellar Radial Velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  5. Hill, G.; Fisher, W. A. (January 1987). "Studies of early-type variable stars. IV. The orbit and physical dimensions for V373 Cas". Astronomy and Astrophysics. 171: 123–130. Bibcode:1987A&A...171..123H.
  6. Lyubimkov, L. S.; et al. (1998). "The binary system V373 Cas: orbital elements, parameters of the components, and helium abundance". Astronomy Reports. 42 (3): 312–321. Bibcode:1998ARep...42..312L.
  7. "V373 Cas". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-11-19.
  8. Lynds, C. R. (September 1959). "The Light-Variation of HD 224151". Astrophysical Journal. 130: 599. Bibcode:1959ApJ...130..599L. doi:10.1086/146748.
  9. "V0373 Cas". Retrieved 2020-11-20.
  10. Karami, K.; Mohebi, R. (December 2009). "Velocity curve studies of spectroscopic binary stars V380 Cygni, V401 Cyg, V523 Cas, V373 Cas and V2388 Oph". Journal of Astrophysics and Astronomy. 30 (3–4): 153–163. Bibcode:2009JApA...30..153K. doi:10.1007/s12036-009-0010-0.
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