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G Doradus
Spectroscopic binary in Dorado. / From Wikipedia, the free encyclopedia
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[16] 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.[17]
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.