A GALEX Far-ultraviolet Study of Dwarf Stars in Moving Groups. (7th October 2019)

• Record Type: Journal Article
• Authors: Cochrane, Kevin M.; Smith, Graeme H.
• Is Part Of: Publications of the Astronomical Society of the Pacific. Volume 131:Number 1005(2019)
• Publication Date: 2019-10-07
• Subjects: open clusters and associations: general -- stars: chromospheres; Astronomy -- Periodicals; Astronomy; Periodicals; Periodicals; 520.5
• DOI: 10.1088/1538-3873/ab3712
• Languages: English
• ISSNs: 0004-6280

Abstract

Abstract: Far-ultraviolet (FUV) GALEX photometry of main-sequence stars in moving groups is used to verify that there is a relationship between age and FUV broadband magnitude among such stars. Samples of dwarf stars were compiled for twelve moving groups and a search made for both GALEX FUV magnitudes on the AB system and Johnson BV photometry. These data sets were used to calculate a (FUV − B ) color index for each star, which in turn was plotted against B − V in a two-color diagram. Based on the loci that the group dwarfs define in this two-color space, there is strong evidence that among candidate members of the Hyades, HR 1614, Wolf 630, Ursa Major, Arcturus, AB Doradus, η Cephei, β Pictoris, and Tucana–Horologium moving groups there are populations of coeval stars. Evidence for coevality is weaker in the case of the ζ Herculis group, and no conclusion can be drawn for candidate stars that have previously been assigned to the Kapteyn's Star and σ Puppis groups. Polynomials of up to fifth order were fitted to the two-color loci of the dwarfs in each group. These fits were used to calculate fiducial values of (FUV − B ) throughout a range in B − V color on the main sequence for most of the groups studied here. Evidence is found that at a fixed B − V there is a logarithmic dependence of (FUV − B ) color on stellar age for FGK dwarfs. The relationships presented herein could potentially serve as a tool for estimating the ages of late-type Population I dwarf stars.