Kappa Cassiopeiae

Kappa Cassiopeiae (κ Cas, κ Cassiopeiae) is a star in the constellation Cassiopeia.

κ Cassiopeiae
Location of κ Cassiopeiae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
Right ascension  00h 32m 59.991s[1]
Declination +62° 55′ 54.42″[1]
Apparent magnitude (V) 4.16[2]
Characteristics
Spectral type BC0.7 Ia[2]
Apparent magnitude (U) 3.50[3]
Apparent magnitude (B) 4.276[3]
Apparent magnitude (J) 4.141[3]
Apparent magnitude (H) 4.148[3]
Apparent magnitude (K) 4.013[3]
U−B color index -0.776[3]
B−V color index +0.0869[3]
J−H color index -0.0069[3]
J−K color index +0.128[3]
Variable type α Cyg[4]
Astrometry
Radial velocity (Rv)0.30[5] km/s
Proper motion (μ) RA: 3.65 ± 0.17[1] mas/yr
Dec.: –2.07 ± 0.16[1] mas/yr
Parallax (π)0.73 ± 0.17[1] mas
Distanceapprox. 4,000 ly
(approx. 1,400 pc)
Absolute magnitude (MV)−7.00[6]
Details[6]
Mass33 M☉
Radius33.0 R☉
Luminosity302,000 L☉
Surface gravity (log g)2.75 cgs
Temperature23,500 K
Rotational velocity (v sin i)66[7] km/s
Other designations
15 Cassiopeiae, HR 130, HD 2905, BD+62°102, FK5 16, HIP 2599, SAO 11256, GC 645
Database references
SIMBADdata
Kappa Cassiopeiae and its bow shock. Spitzer infrared image (NASA/JPL-Caltech)

κ Cassiopeiae has an unusual spectrum that has anomalously weak nitrogen lines, taken as an actual nitrogen deficiency in the atmosphere. This is indicated by the modified letter C. It is also interpolated to BC0.7, being slightly hotter than a standard B1 star.[8][9] It is assumed to be a member of the Cas OB14 stellar association at about 1,100 parsecs, while its distance found from the Hipparcos parallax is 1,369 parsecs.[9]

It is classified as an Alpha Cygni type variable star and its brightness varies by a few hundredths of a magnitude. Periods of two hours,[10] nine days,[11] and 2.65 days[12] have been reported from observations at different times.

It is a runaway star, moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second). Its magnetic field and wind of particles creates a visible bow shock 4 light-years ahead of it, colliding with the diffuse, and usually invisible, interstellar gas and dust. This is about the same distance that Earth is from Proxima Centauri, the nearest star to the Sun.[13] The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.[14]

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.Vizier catalog entry
  2. Kraus, M.; Borges Fernandes, M.; Kubát, J. (2009). "Parameters of galactic early B supergiants. The influence of the wind on the interstellar extinction determination". Astronomy and Astrophysics. 499: 291. Bibcode:2009A&A...499..291K. doi:10.1051/0004-6361/200810319.
  3. 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.
  4. 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.
  5. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. Searle, S. C.; Prinja, R. K.; Massa, D.; Ryans, R. (2008). "Quantitative studies of the optical and UV spectra of Galactic early B supergiants. I. Fundamental parameters". Astronomy and Astrophysics. 481 (3): 777. arXiv:0801.4289. Bibcode:2008A&A...481..777S. doi:10.1051/0004-6361:20077125.
  7. Simón-Díaz, S.; Herrero, A. (2014). "The IACOB project. I. Rotational velocities in northern Galactic O- and early B-type stars revisited. The impact of other sources of line-broadening". Astronomy & Astrophysics. 562: A135. arXiv:1311.3360. Bibcode:2014A&A...562A.135S. doi:10.1051/0004-6361/201322758.
  8. Walborn, Nolan R. (1971). "Some Spectroscopic Characteristics of the OB Stars: An Investigation of the Space Distribution of Certain OB Stars and the Reference Frame of the Classification". Astrophysical Journal Supplement. 23: 257. Bibcode:1971ApJS...23..257W. doi:10.1086/190239.
  9. Walborn, Nolan R. (1971). "On the Existence of OB Stars with Anomalous Nitrogen and Carbon Spectra". Astrophysical Journal. 164: L67. Bibcode:1971ApJ...164L..67W. doi:10.1086/180693.
  10. Elst, E. W. (1979). "Spectroscopic and Photometric Variation of kappa Cas". Information Bulletin on Variable Stars. 1697: 1. Bibcode:1979IBVS.1697....1E.
  11. Percy, J. R. (1981). "Photometric Variability of kappa Cassiopeiae". Information Bulletin on Variable Stars. 1946: 1. Bibcode:1981IBVS.1946....1P.
  12. Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331: 45. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x.
  13. Clavin, Whitney (21 February 2014). "The bow shock of Kappa Cassiopeiae, a massive, hot supergiant". Phys.org. Retrieved 6 December 2016.
  14. Peri, C. S.; Benaglia, P.; Brookes, D. P.; Stevens, I. R.; Isequilla, N. L. (2012). "E-BOSS: An Extensive stellar BOw Shock Survey. I. Methods and first catalogue". Astronomy & Astrophysics. 538: A108. arXiv:1109.3689. Bibcode:2012A&A...538A.108P. doi:10.1051/0004-6361/201118116.
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