A measurement of radius inflation in the Pleiades and its relation to rotation and lithium depletion. (2017)
Keywords :
stars activity - stars: fundamental parameters - stars: rotation - starspot
Abstract:Precise measurements of eclipsing binary parameters and statistical studies of young clusters have suggested that some magnetically active low-mass dwarfs possess radii inflated by ~5%-15% relative to theoretical expectations. If true, this effect should be pronounced in young open clusters, due to the rapid rotation and strong magnetic activity of their most extreme members. We explore this possibility by determining empirical radii for 83 members of the nearby Pleiades open cluster, using spectral energy distribution fitting to establish F_bol_ with a typical accuracy of ~3% together with color and spectro-photometric indices to determine T_eff_. We find several Pleiades members with radii inflated above radius-T_eff_ models from
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We began with the newly assembled catalog of literature lithium
measurements reported by Barrado et al. (2016, J/A+A/596/A113), who
accepted only stars with membership probability >0.75. A small number
of Pleiads lie behind an HI cloud, and are thus far more extincted
than the rest (e.g., Gordon & Arny 1984AJ.....89..672G); for simplicity,
we discard these members. We then cross-correlated this sample with
the famous UBV photometric catalog of Johnson & Mitchell
(1958ApJ...128...31J), who produced homogeneous photometry for a large
sample of Pleiades members. We further selected stars with measured
rotation rates, either from the HATNet collaboration (Hartman et al.
2010, J/MNRAS/408/475), or the recent analysis of K2 data (Rebull et al.
2016, J/AJ/152/113, J/AJ/152/114; Stauffer et al. 2016, J/AJ/152/115),
preferring the latter for joint detections. Finally, we queried VizieR
(http://vizier.u-strasbg.fr/) to obtain K_S_-band magnitudes from the
Two-Micron All-Sky Survey (2MASS) catalog (Skrutskie et al. 2006,
Cat. VII/233), which detected every star in our reduced sample. These
criteria produced a total of 83 high-probability cluster members,
stretching from early-F to late-K type.
- I/258 : Pleiades positions and proper motions (Wang+, 1996)
- I/259 : The Tycho-2 Catalogue (Hog+ 2000)
- VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
- J/AJ/106/1059 : Lithium in the Pleiades (Soderblom+, 1993)
- J/ApJS/172/663 : Infrared observations of the Pleiades (Stauffer+, 2007)
- J/MNRAS/408/475 : HATNet Pleiades Rotation Period Catalogue (Hartman+, 2010)
- J/AJ/148/30 : BVI photometry of 350 Pleiades stars (Kamai+, 2014)
- J/A+A/596/A113 : The Seven Sisters DANCe. II. Pleiades (Barrado+, 2016)
- J/AJ/152/113 : Pleiades members with K2 light curves. I. Periods
- J/AJ/152/114 : Pleiades members with K2 light curves. II. (Rebull+, 2016)
- J/AJ/152/115 : Pleiades members with K2 light curves. III. (Stauffer+, 2016)
