Astronomy:Kappa Doradus

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Short description: Suspected variable in the constellation Dorado
κ Doradus
Dorado constellation map.svg
Red circle.svg
Location of κ Doradus on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Dorado
Right ascension  04h 44m 21.17834s[1]
Declination −59° 43′ 57.8563″[1]
Apparent magnitude (V) 5.28[2] (5.27 - 5.30)[3]
Characteristics
Spectral type A8 IV[4]
B−V color index +0.20[5]
Variable type suspected δ Scuti[3]
Astrometry
Radial velocity (Rv)0.00±3.70[6] km/s
Proper motion (μ) RA: +23.860[1] mas/yr
Dec.: +39.974[1] mas/yr
Parallax (π)14.8207 ± 0.0795[1] mas
Distance220 ± 1 ly
(67.5 ± 0.4 pc)
Absolute magnitude (MV)+1.15[7]
Details
Mass1.78+0.36−0.20[8] M☉
Radius2.88+0.21−0.19[9] R☉
Luminosity26.6[10] L☉
Surface gravity (log g)3.79±0.08[9] cgs
Temperature7,623±123[11] K
Metallicity [Fe/H]−0.18[12] dex
Rotational velocity (v sin i)230[13] km/s
Other designations
κ Dor, NSV 16162, CPD−59°376, FK5 2354, GC 5810, HD 30478, HIP 22040, HR 1530, SAO 233664[14]
Database references
SIMBADdata

Kappa Doradus, Latinized from κ Doradus, is a solitary star[15] located in the southern constellation Dorado. It is faintly visible to the naked eye as a white-hued point of light with an apparent magnitude of 5.28.[2] The object is located relatively close at a distance of 220 light-years based on Gaia DR3 parallax measurements[1] and its distance from the Solar System is not changing, having a somewhat constrained heliocentric radial velocity of 0.00 km/s.[6] At its current distance, Kappa Doradus' brightness is diminished by two-tenths of a magnitude due to interstellar extinction[16] and it has an absolute magnitude of +1.15.[7]

The object has been given many different classes. Houk & Cowley (1975) gave a class of A8/9 III/IV,[17] indicating that it is an evolved A-type star with the characteristics of an A8 and A9 star and the blended luminosity class of a giant star and a subgiant. It has also been given a class of A8 IV and A5 III,[4][18] indicating either a slightly evolved subgiant or an evolved giant star. Kappa Doradus has 1.78 times the mass of the Sun[8] and 2.88 times the radius of the Sun.[9] However, this is only its polar radius, as it has an equatorial bulge 26% greater than its polar radius.[19] It radiates 26.6 times the luminosity of the Sun[10] from its photosphere at an effective temperature of 7,623 K.[11] Kappa Doradus is metal deficient with an iron abundance 66.1% of the Sun's or [Fe/H] = −0.18.[12] Like many hot stars it spins rapidly, having a projected rotational velocity of 230 km/s,[13] which causes the aforementioned oblation.[19]

Kappa Doradus variability was first observed in 1981 by astronomer H. M. Matizen.[20] In the paper, it is used as a comparison star for Alpha Doradus. Matizen found out that Kappa Doradus show Delta Scuti-like amplitudes of 0.03 magnitudes in the visual passband within hours.[3] As of 2004 however, it has not been confirmed to be variable.[21]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 3.2 Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80–88. doi:10.1134/S1063772917010085. ISSN 1063-7729. Bibcode: 2017ARep...61...80S. 
  4. ↑ 4.0 4.1 Gray, R. O.; Garrison, R. F. (July 1989). "The late A-type stars - Refined MK classification, confrontation with Stromgren photometry, and the effects of rotation". The Astrophysical Journal Supplement Series 70: 623. doi:10.1086/191349. ISSN 0067-0049. Bibcode: 1989ApJS...70..623G. 
  5. ↑ Lake, R. (1965). "Photometric Magnitudes and Colours for Bright Southern Stars (Sixth List)". Monthly Notes of the Astronomical Society of South Africa 24: 41. ISSN 0024-8266. Bibcode: 1965MNSSA..24...41L. 
  6. ↑ 6.0 6.1 Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (November 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten 328 (9): 889–896. doi:10.1002/asna.200710776. ISSN 0004-6337. Bibcode: 2007AN....328..889K. 
  7. ↑ 7.0 7.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  9. ↑ 9.0 9.1 9.2 Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics 352: 555–562. ISSN 0004-6361. Bibcode: 1999A&A...352..555A. 
  10. ↑ 10.0 10.1 McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society 427 (1): 343–357. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711. Bibcode: 2012MNRAS.427..343M. 
  11. ↑ 11.0 11.1 Paunzen, E.; Schnell, A.; Maitzen, H. M. (October 2006). "An empirical temperature calibration for the Δa photometric system II: The A-type and mid F-type stars". Astronomy & Astrophysics 458 (1): 293–296. doi:10.1051/0004-6361:20064889. ISSN 0004-6361. Bibcode: 2006A&A...458..293P. 
  12. ↑ 12.0 12.1 Anders, F. et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  13. ↑ 13.0 13.1 Huang, Su-Shu (September 1953). "A Statistical Study of the Rotation of the Stars.". The Astrophysical Journal 118: 285. doi:10.1086/145751. ISSN 0004-637X. Bibcode: 1953ApJ...118..285H. 
  14. ↑ "* kap Dor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+kap+Dor. 
  15. ↑ Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society 389 (2): 869–879. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E. 
  16. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  17. ↑ Houk, N.; Cowley, A. P. (1975). University of Michigan Catalogue of two-dimensional spectral types for the HD stars: Declinations −90° to −53°. 1. Bibcode: 1975mcts.book.....H. 
  18. ↑ Abt, Helmut A.; Morrell, Nidia I. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series 99: 135. doi:10.1086/192182. ISSN 0067-0049. Bibcode: 1995ApJS...99..135A. 
  19. ↑ 19.0 19.1 van Belle, Gerard T. (14 March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review 20 (1): 51. doi:10.1007/s00159-012-0051-2. ISSN 0935-4956. Bibcode: 2012A&ARv..20...51V. 
  20. ↑ Maitzen, H. M. (April 1981). "Variability of the Extreme Silicon Star alpha Dor = HD 29305". Information Bulletin on Variable Stars 1950: 1. ISSN 0374-0676. Bibcode: 1981IBVS.1950....1M. 
  21. ↑ Samus, N. N.; Durlevich, O. V. (November 2004). "VizieR Online Data Catalog: Combined General Catalogue of Variable Stars (Samus+ 2004)". VizieR Online Data Catalog: II/250. Bibcode: 2004yCat.2250....0S. 
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