Astronomy:Kappa Scorpii

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Short description: Star in the constellation Scorpius
κ Scorpii
Location of κ Sco (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Scorpius
Right ascension  17h 42m 29.27520s[1]
Declination −39° 01′ 47.9391″[1]
Apparent magnitude (V) 2.41 - 2.42[2]
Characteristics
Spectral type B1.5 III[3]
U−B color index −0.914[4]
B−V color index −0.228[4]
Variable type β Cephei[2]
Astrometry
Radial velocity (Rv)−14.0[5] km/s
Proper motion (μ) RA: −6.05[1] mas/yr
Dec.: −25.54[1] mas/yr
Parallax (π)6.75 ± 0.17[1] mas
Distance480 ± 10 ly
(148 ± 4 pc)
Absolute magnitude (MV)−3.48±0.06[6]
Orbit[7][note 1]
Period (P)195.458±0.007 days
Semi-major axis (a)10.91±0.12 mas
Eccentricity (e)0.520±0.006
Inclination (i)102.3±0.2°
Longitude of the node (Ω)281.96±0.12°
Periastron epoch (T)2449983.23±0.4
Argument of periastron (ω)
(secondary)		87.6±0.6°
Semi-amplitude (K1)
(primary)		48.0±0.3[8] km/s
Details[6]
κ Sco A
Mass10.2±0.3 M☉
Radius6.45±0.55 R☉
Surface gravity (log g)3.83±0.06 cgs
Temperature23,170 K
Rotation2.97±0.25 days
Rotational velocity (v sin i)105[9] km/s
Age15.1+1.8
−1.6 Myr
κ Sco B
Mass9.3±0.3 M☉
Radius5.8[8] R☉
Surface gravity (log g)3.92 cgs
Temperature22,750 K
Age15.1+1.8
−1.6 Myr
Other designations
Girtab, κ Sco, CD−38°12137, CPD−38°6992, FK5 660, HD 160578, HIP 86670, HR 6580, SAO 209163
Database references
SIMBADdata

Kappa Scorpii, Latinized from κ Scorpii, is a binary star system in the southern constellation of Scorpius. With an apparent visual magnitude of 2.4, this star system is readily visible to the naked eye. Parallax measurements place it at an estimated distance of roughly 480 light-years (150 parsecs) from the Earth.

Nomenclature

κ Scorpii has been called Girtab /ˈɡɜːrtæb/,[10] which is the Sumerian word for 'scorpion'. The name has survived through the Babylonian star catalogues,[11] and was originally applied to an asterism comprising this star, λ Scorpii, υ Scorpii, and ι Scorpii.[10] Other sources have used the name Girtab for θ Scorpii (Sargas)[12] or ι1 Scorpii.[13] The latter appeared in a 1971 NASA catalog of star names that listed κ Scorpii as Mula, after an Indian asterism (nakshatra) in the same region.[13]

In Chinese, 尾宿 (Wěi Xiù), meaning Tail, refers to an asterism consisting κ Scorpii, μ1 Scorpii, ε Scorpii, ζ1 Scorpii and ζ2 Scorpii, η Scorpii, θ Scorpii, ι1 Scorpii and ι2 Scorpii, λ Scorpii and υ Scorpii.[14] Consequently, the Chinese name for κ Scorpii itself is 尾宿七 (Wěi Xiù qī), "the Seventh Star of Tail".[15]

Properties

This is a spectroscopic binary, which is a type of binary star system in which the two stars are so close together that they have not been individually resolved with a telescope. The pair orbit each other with a period of about 195 days and an eccentricity of about 0.5.[7] The combined spectrum of this pair matches a star with a stellar classification of B1.5 III.[3] The 'III' luminosity class indicates the presence of a giant star that has exhausted the supply of hydrogen at its core and is in a late evolutionary stage.

A light curve for Kappa Scorpii, adapted from Lomb and Shobbrook (1975)[16]

The primary component of the pair, κ Sco A, is a variable star of Beta Cephei type. It is undergoing radial pulsations with a dominant frequency of five cycles per day, or 4.8 hours per cycle. There are overlapping secondary pulsation frequencies of about 4.85 and 5.69 cycles per day.[17] This star has about 11 times the mass of the Sun and is nearly 7 times the Sun's radius.[7][8] The effective temperature of the outer envelope is 23,400 K,[8] giving it a blue-white hue. It is rotating rapidly, with an estimated period of only 1.9 days and an axis of rotation that is inclined by about 40° to the line of sight from the Earth.[8]

The secondary component, κ Sco B, is smaller than the primary, but still much larger than the Sun. It has about 10 times the mass of the Sun and nearly six times the Sun's radius.[7][8] The effective temperature of 18,800 K[8] is also higher than the Sun's, which is at 5,778 K.

Cultural significance

κ Scorpii appears on the flag of Brazil, symbolising the state of Paraíba.[18]

Notes

  1. ↑ from "Fixed Period Only" model

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V 
  2. ↑ 2.0 2.1 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S. 
  3. ↑ 3.0 3.1 Houk, Nancy (1978), "Michigan catalogue of two-dimensional spectral types for the HD star", Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 3. Declinations -40.0° to -26.0° (Ann Arbor: Dept. of Astronomy, University of Michigan: distributed by University Microfilms International) 3, Bibcode: 1982mcts.book.....H 
  4. ↑ 4.0 4.1 Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement 15: 459, doi:10.1086/190168, Bibcode: 1968ApJS...15..459G 
  5. ↑ Wielen, R. et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb (Astronomisches Rechen-Institut Heidelberg) 35 (35): 1, Bibcode: 1999VeARI..35....1W 
  6. ↑ 6.0 6.1 Handler, G.; Schwarzenberg-Czerny, A. (2013). "Time-resolved multicolour photometry of bright B-type variable stars in Scorpius". Astronomy & Astrophysics 557: A1. doi:10.1051/0004-6361/201321886. Bibcode: 2013A&A...557A...1H. 
  7. ↑ 7.0 7.1 7.2 7.3 Robertson, J. Gordon; Ireland, Michael J.; Tango, William J.; Tuthill, Peter G.; Warrington, Benjamin A.; Kok, Yitping; Rizzuto, A. C.; Cheetham, Anthony et al. (12 September 2012). "Science and technology progress at the Sydney University Stellar Interferometer". Optical and Infrared Interferometry III. 8445. Proceedings of the SPIE. doi:10.1117/12.924946. 84450N. Bibcode: 2012SPIE.8445E..0NR. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 Uytterhoeven, K. et al. (June 2001), "Line-profile variations of the double-lined spectroscopic binary kappa Scorpii", Astronomy and Astrophysics 371 (3): 1035–1047, doi:10.1051/0004-6361:20010456, Bibcode: 2001A&A...371.1035U 
  9. ↑ Bernacca, P. L.; Perinotto, M. (1970), "A Catalogue of Stellar Rotational Velocities", Contributi Osservatorio Astronomico di Padova in Asiago 239 (1): 1, Bibcode: 1970CoAsi.239....1B 
  10. ↑ 10.0 10.1 Falkner, David E. (2011), The Mythology of the Night Sky: An Amateur Astronomer's Guide to the Ancient Greek and Roman Legends, Patrick Moore's Practical Astronomy, Springer, p. 106, ISBN 978-1-4614-0136-0, https://books.google.com/books?id=tyj8UUE968wC&pg=PA106 
  11. ↑ Ridpath, Ian (1989), Star tales, James Clarke & Co., p. 114, ISBN 0-7188-2695-7, https://books.google.com/books?id=gFrdcTdeVaEC&pg=RA1-PA14 
  12. ↑ Kaler, James B., "Girtab", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/girtab.html 
  13. ↑ 13.0 13.1 Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology, https://ntrs.nasa.gov/api/citations/19720005197/downloads/19720005197.pdf. 
  14. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  15. ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum. Accessed on line November 23, 2010.
  16. ↑ Lomb, N. R.; Shobbrook, R. R. (December 1975). "New radial velocities and further photometric observations of lambda Sco and kappa Sco". Monthly Notices of the Royal Astronomical Society 173 (3): 709–728. doi:10.1093/mnras/173.3.709. Bibcode: 1975MNRAS.173..709L. https://articles.adsabs.harvard.edu/pdf/1975MNRAS.173..709L. Retrieved 18 August 2022. 
  17. ↑ Uytterhoeven, K. et al. (March 2005), "Disentangling component spectra of κ Scorpii, a spectroscopic binary with a pulsating primary. II. Interpretation of the line-profile variability", Astronomy and Astrophysics 432 (3): 955–967, doi:10.1051/0004-6361:20041444, Bibcode: 2005A&A...432..955U 
  18. ↑ "Astronomy of the Brazilian Flag". FOTW Flags Of The World website. https://flagspot.net/flags/br_astro.html. 

Coordinates: Sky map 17h 42m 29.27520s, −39° 01′ 47.9391″



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