V381 Cephei

V381 Cephei (HR 8164) is a triple star system in the northern constellation of Cepheus. Its apparent magnitude is slightly variable between 5.5 and 5.7.

V381 Cephei
Location of V381 Cephei (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cepheus
Right ascension 21h 19m 15.682s[1]
Declination +58° 37′ 24.550″[1]
Apparent magnitude (V) 5.51 - 5.71[2]
Characteristics
Spectral type M1epIb + B[3]
U−B color index 0.00[4]
B−V color index +1.34[4]
Variable type Lc[2]
Astrometry
Radial velocity (Rv)−14.10[5] km/s
Proper motion (μ) RA: −1.435[6] mas/yr
Dec.: −5.427[6] mas/yr
Parallax (π)1.59 ± 0.23 mas[6]
Distanceapprox. 2,100 ly
(approx. 630 pc)
Absolute magnitude (MV)−5.2[7]
Details
Aa
Mass7.2[8] - 16[9] M☉
Radius276[1] R☉
Luminosity12,940 - 13,550[1] L☉
Temperature3,745±170[1] K
Ab
Mass13[9] M☉
B
Mass11[9] M☉
Age49.1[8] Myr
Other designations
V381 Cephei, HR 8164, HIP 105259, BD+58°2249, ADS 14864, 2MASS J21191567+5837246, WDS J21193+5837
A: HD 203338
B: HD 203339
Database references
SIMBADdata

System

V381 Cephei is a visual double star with components A and B separated by 4.6". The primary is HD 203338 and the secondary is the magnitude 9.2 HD 203339.[9]

HD 203338 is itself a spectroscopic binary with components Aa and Ab orbiting every 280 years.[9] It forms a VV Cephei-type binary system with a hot companion which is accreting mass from the primary. The long period means that it exhibits fewer peculiarities than other VV Cephei binaries.[10]

Properties
A visual band light curve for V381 Cephei, adapted from Halbedel (1991)[11]

Component Aa is a red supergiant and its close companion is a B2 main sequence star. The supergiant is a pulsating variable with a small amplitude and poorly defined period. It is generally given spectral class qualifiers indicating peculiarities and emission, which may be associated with the disc around the hot secondary.[10]

Component B, HD 203339, is a B3 main sequence star with a mass around 11 M☉.[9]

References
  1. Messineo, M.; Brown, A. G. A. (2019). "A Catalog of Known Galactic K-M Stars of Class I Candidate Red Supergiants in Gaia DR2". The Astronomical Journal. 158 (1): 20. arXiv:1905.03744. Bibcode:2019AJ....158...20M. doi:10.3847/1538-3881/ab1cbd. S2CID 148571616.
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. Josselin, E.; Plez, B. (2007). "Atmospheric dynamics and the mass loss process in red supergiant stars". Astronomy and Astrophysics. 469 (2): 671. arXiv:0705.0266. Bibcode:2007A&A...469..671J. doi:10.1051/0004-6361:20066353. S2CID 17789027.
  4. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  5. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  6. 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.
  7. Stothers, R.; Leung, K. C. (1971). "Luminosities, masses and periodicities of massive red supergiants". Astronomy and Astrophysics. 10: 290. Bibcode:1971A&A....10..290S.
  8. Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873.
  9. Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
  10. Halbedel, Elaine M. (1991). "Photometric variability for the VV Cephei-like star HR 8164". Astronomical Society of the Pacific. 103: 310. Bibcode:1991PASP..103..310H. doi:10.1086/132820.
  11. Halbedel, Elaine M. (March 1991). "Photometric Variability for the VV Cephei-Like Star HR 8164". Publications of the Astronomical Society of the Pacific. 103: 310. doi:10.1086/132820. Retrieved 6 December 2021.
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