Xi Cassiopeiae

Xi Cassiopeiae (ξ Cassiopeiae) is a blue-white hued binary star[6] system in the northern constellation of Cassiopeia. It has an apparent visual magnitude of +4.81[2] and thus is faintly visible to the naked eye. Based upon an annual parallax shift of 2.28 mas as seen from Earth,[1] this system is located roughly 1,400 light years from the Sun. At that distance, the visual magnitude of the system is diminished by an extinction factor of 0.20 due to interstellar dust.[5] It is advancing in the general direction of the Sun with a radial velocity of roughly −10.6 km/s.[4]

Xi Cassiopeiae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cassiopeia
Right ascension  00h 42m 03.89542s[1]
Declination +50° 30′ 45.0915″[1]
Apparent magnitude (V) +4.81[2]
Characteristics
Spectral type B2.5 V[3]
U−B color index −0.60[2]
B−V color index −0.11[2]
Astrometry
Radial velocity (Rv)−10.6±7.4[4] km/s
Proper motion (μ) RA: +12.24±0.38[1] mas/yr
Dec.: −6.58±0.32[1] mas/yr
Parallax (π)2.28 ± 0.51[1] mas
Distanceapprox. 1,400 ly
(approx. 440 pc)
Absolute magnitude (MV)−0.42[5]
Orbit[6]
Period (P)940.2 d
Eccentricity (e)0.4
Periastron epoch (T)2441738 JD
Argument of periastron (ω)
(secondary)		119°
Semi-amplitude (K1)
(primary)		11.90 km/s
Details
Mass10.1±0.1[7] M☉
Radius4.5[8] R☉
Luminosity2,873[9] L☉
Surface gravity (log g)3.571±0.032[10] cgs
Temperature15,585±250[10] K
Rotational velocity (v sin i)139±7[11] km/s
Age19[10] Myr
Other designations
ξ Cas, 19 Cas, BD+49° 164, FK5 2046, HD 3901, HIP 3300, HR 179, SAO 21637[12]
Database references
SIMBADdata

This is a single-lined spectroscopic binary star system with an orbital period of 940.2 days and an eccentricity of 0.4.[6] The visible component has the spectrum of a B-type main-sequence star with a stellar classification of B2.5 V.[3] It has an estimated 10.1[7] times the mass of the Sun and around 4.5[8] times the Sun's radius. At the age of 19[10] million years, it has a high rate of rotation with a projected rotational velocity of about 139 km/s.[11] The star is radiating 2,873[9] times the Sun's luminosity from its photosphere at an effective temperature of around 15,585 K.[10]

References
  1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. Crawford, D. L.; et al. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220.
  3. Lesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?", Astrophysical Journal Supplement, 17: 371, Bibcode:1968ApJS...17..371L, doi:10.1086/190179
  4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  5. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  6. Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
  7. Tetzlaff, N.; et al. (January 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.
  8. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy & Astrophysics (3rd ed.), 367: 521–24, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  9. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  10. Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, arXiv:1604.06456, Bibcode:2016AJ....152...40G, doi:10.3847/0004-6256/152/2/40, 40.
  11. Huang, Wenjin; et al. (October 2010), "A Stellar Rotation Census of B Stars: From ZAMS to TAMS", The Astrophysical Journal, 722 (1): 605–619, arXiv:1008.1761, Bibcode:2010ApJ...722..605H, doi:10.1088/0004-637X/722/1/605.
  12. "ksi Cas". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-30.
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