Astronomy:G Doradus

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Short description: Spectroscopic binary in Dorado.
G Doradus
Dorado constellation map.svg
Red circle.svg
Location of G Doradus on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Dorado
Right ascension  05h 32m 59.56572s[1]
Declination −64° 13′ 39.0537″[1]
Apparent magnitude (V) 5.34±0.01[2]
Characteristics
Spectral type G8/K0 III[3]
U−B color index +0.85[4]
B−V color index +1.04[4]
Astrometry
Radial velocity (Rv)9.8±2.8[5] km/s
Proper motion (μ) RA: +45.741[1] mas/yr
Dec.: −3.051[1] mas/yr
Parallax (π)13.9330 ± 0.2335[1] mas
Distance234 ± 4 ly
(72 ± 1 pc)
Absolute magnitude (MV)+1.08[6]
Orbit[7]
Period (P)180.8757 d
Semi-major axis (a)0.320 astronomical unit|AU
Eccentricity (e)0.509±0.010
Inclination (i)52.2±5.2[8]°
Longitude of the node (Ω)45.4±6.6[8]°
Periastron epoch (T)2,423,108.42±0.65 JD
Argument of periastron (ω)
(secondary)		332.93±1.61°
Semi-amplitude (K1)
(primary)		22.36±0.35 km/s
Details
A
Mass3.47[9] M☉
Radius10.5+0.1−0.2[1] R☉
Luminosity48.4+1.6−1.5[1] L☉
Surface gravity (log g)2.61[10] cgs
Temperature4819±123[11] K
Metallicity [Fe/H]−0.20[12] dex
Rotational velocity (v sin i)<1.0[13] km/s
Age556+153−188[1] Myr
B
Mass1.87[9] M☉
Other designations
G Dor, CPD−64°456, FK5 2418, GC 6927, HD 37297, HIP 26001, HR 1917, SAO 249309[14]
Database references
SIMBADdata

G Doradus (HD 37297; HR 1917; 28 G. Doradus) is a spectroscopic binary located in the southern constellation Dorado, the dolphinfish. It has an apparent magnitude of 5.34,[2] making it faintly visible to the naked eye under ideal conditions. The system is located relatively close at a distance of 234 light-years based on Gaia DR3 parallax measurements but it is receding with a heliocentric radial velocity of approximately 9.8 km/s.[5] At its current distance, G Doradus' brightness is diminished by a quarter of a magnitude due to interstellar extinction[15] and it has an absolute magnitude of +1.08.[6] The bayer designation "G Doradus" was not assigned by Benjamin Gould or Lacaille. It merely arose due to the designation assigned by Gould; 28 G. Doradus.[16]

The visible component has a stellar classification of G8/K0 III,[3] indicating that it is an evolved star with the characteristics of a G8 and K0 giant star. It has 3.47 times the mass of the Sun[9] but at the age of 556 million years, it has expanded to 10.5 times the radius of the Sun.[1] It radiates 48.4 times the luminosity of the Sun[1] from its enlarged photosphere at an effective temperature of 4,819 K,[11] giving it an orangish-yellow hue when viewed in the night sky. G Doradus is slightly metal deficient with an iron abundance of [Fe/H] = −0.20[12] and it spins too slowly for its projected rotational velocity to be measured accurately.[13]

G Doradus is a single-lined spectroscopic binary; the components – which have a separation of 0.32 AU – take 181 days to circle each other in an elliptical orbit, but the orbit is not well constrained.[7] Although only the primary can be observed in the spectrum, the masses of both components can be determined. Krachieva et al. (1980) derives a mass of 1.87 M☉ for the companion,[9] which might be an A-type star.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 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 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. 
  4. ↑ 4.0 4.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J. 
  5. ↑ 5.0 5.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  6. ↑ 6.0 6.1 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. 
  7. ↑ 7.0 7.1 Lunt, Joseph (1924). "On the orbits of the seven spectroscopic-binary stars : ί Gruis, θ1 Crucis, 28 Doradus, α Phoenicis, β Doradus, W Velorum, ρ Tucanae". Annals of the Cape Observatory 10: 7. Bibcode: 1924AnCap..10....7L. 
  8. ↑ 8.0 8.1 Jancart, S.; Jorissen, A.; Babusiaux, C.; Pourbaix, D. (September 30, 2005). "Astrometric orbits of SB9 stars". Astronomy & Astrophysics (EDP Sciences) 442 (1): 365–380. doi:10.1051/0004-6361:20053003. ISSN 0004-6361. Bibcode: 2005A&A...442..365J. 
  9. ↑ 9.0 9.1 9.2 9.3 Kraicheva, Z.; Popova, E.; Tutukov, A.; Yungelson, L. (July 1980). "Catalogue of physical parameters of spectroscopic binary stars.". Bull. Inf. Centre Données Stellaires 19: 71. Bibcode: 1980BICDS..19...71K. 
  10. ↑ 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. 
  11. ↑ 11.0 11.1 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. 
  12. ↑ 12.0 12.1 Eggen, Olin J. (January 1989). "Large and Kinematically Unbiased Samples of G- and K-Type Stars. III. Evolved Young Disk Stars in the Bright Star Sample". Publications of the Astronomical Society of the Pacific 101: 54. doi:10.1086/132404. ISSN 0004-6280. Bibcode: 1989PASP..101...54E. 
  13. ↑ 13.0 13.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars *". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D. 
  14. ↑ "* G Dor". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+G+Dor. 
  15. ↑ 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. 
  16. ↑ Wagman, Morton (2003). Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others. Blacksburg, VA: The McDonald & Woodward Publishing Company. pp. 137. ISBN 978-0-939923-78-6. 
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