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Kappa Cassiopeiae

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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) 4.12 - 4.21[2]
Characteristics
Spectral type BC0.7 Ia[3]
Apparent magnitude (U) 3.50[4]
Apparent magnitude (B) 4.276[4]
Apparent magnitude (J) 4.141[4]
Apparent magnitude (H) 4.148[4]
Apparent magnitude (K) 4.013[4]
U−B color index −0.776[4]
B−V color index +0.0869[4]
J−H color index −0.0069[4]
J−K color index +0.128[4]
Variable type α Cyg[5]
Astrometry
Radial velocity (Rv)0.30[6] km/s
Proper motion (μ) RA: +3.65[1] mas/yr
Dec.: −2.07[1] mas/yr
Parallax (π)0.73 ± 0.17 mas[1]
Distanceapprox. 4,000 ly
(approx. 1,400 pc)
Absolute magnitude (MV)−7.1[7]
Details
Mass33[8] M☉
Radius39[7] R☉
Luminosity490,000[7] L☉
Surface gravity (log g)2.79[7] cgs
Temperature24,600[7] K
Rotational velocity (v sin i)58[7] km/s
Age4.5[9] Myr
Other designations
15 Cassiopeiae, HR 130, HD 2905, BD+62°102, FK5 16, HIP 2599, SAO 11256, GC 645, MWC 7
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 on the assumption that it is also carbon-rich, although this might not actually be the case.[8] It is also interpolated to BC0.7, being slightly hotter than a standard B1 star.[10][11]

κ Cassiopeiae is assumed to be a member of the Cassiopeia OB14 stellar association (Cas OB14) and treated as being at a distance of about 1,100 pc,[11] while its distance found from the Hipparcos parallax is about 1,400 parsecs.[1] Its Gaia parallaxes are somewhat uncertain due to the brightness of the star, but a modern determination of the distance to Cas OB14 is 880 pc.[12]

A light curve for Kappa Cassiopeiae, plotted from Hipparcos data[13]

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,[14] 2.65 days,[15] and nine days[16] have been reported from observations at different times.

It is a runaway star. 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.[17] The dimensions of the bow shock are vast: around 12 light-years long and 1.8 light-years wide.[18]

References

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  1. ^ a b c d e f 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. S2CID 18759600.Vizier catalog entry
  2. ^ "kappa Cas". Omternational Variable Star Index. AAVSO. Retrieved 2022-08-13.
  3. ^ 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 (1): 291. Bibcode:2009A&A...499..291K. doi:10.1051/0004-6361/200810319.
  4. ^ a b c d e f g h i 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. ^ 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.
  6. ^ 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.
  7. ^ a b c d e f Simón-Díaz, S.; Aerts, C.; Urbaneja, M. A.; Camacho, I.; Antoci, V.; Fredslund Andersen, M.; Grundahl, F.; Pallé, P. L. (2018). "Low-frequency photospheric and wind variability in the early-B supergiant HD 2905". Astronomy and Astrophysics. 612: A40. arXiv:1711.08994. Bibcode:2018A&A...612A..40S. doi:10.1051/0004-6361/201732160. S2CID 20158464.
  8. ^ a b 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. S2CID 1552752.
  9. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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. S2CID 118629873.
  10. ^ 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.
  11. ^ a b 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.
  12. ^ Melnik, A. M.; Dambis, A. K. (April 2020). "Internal motions in OB associations with Gaia DR2". Monthly Notices of the Royal Astronomical Society. 493 (2): 2339–2351. arXiv:2002.05044. Bibcode:2020MNRAS.493.2339M. doi:10.1093/mnras/staa454.
  13. ^ "Light Curve". Hipparcos ESA. ESA. Retrieved 17 February 2022.
  14. ^ Elst, E. W. (1979). "Spectroscopic and Photometric Variation of kappa Cas". Information Bulletin on Variable Stars. 1697: 1. Bibcode:1979IBVS.1697....1E.
  15. ^ Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x. S2CID 10505995.
  16. ^ Percy, J. R. (1981). "Photometric Variability of kappa Cassiopeiae". Information Bulletin on Variable Stars. 1946: 1. Bibcode:1981IBVS.1946....1P.
  17. ^ Clavin, Whitney (21 February 2014). "The bow shock of Kappa Cassiopeiae, a massive, hot supergiant". Phys.org. Retrieved 6 December 2016.
  18. ^ 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. S2CID 62840857.
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