Stellar rotation in the Hyades and Praesepe: gyrochronology and braking time-scale

We present the results of photometric surveys for stellar rotation in the Hyades and in Praesepe, using data obtained as part of the SuperWASP exoplanetary transit-search programme. We determined accurate rotation periods for more than 120 sources whose cluster membership was confirmed by common pro...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society 2011-05, Vol.413 (3), p.2218-2234
Main Authors: Delorme, P., Cameron, A. Collier, Hebb, L., Rostron, J., Lister, T. A., Norton, A. J., Pollacco, D., West, R. G.
Format: Article
Language:English
Subjects:
Astronomical bodies
Astronomy
Braking
Earth, ocean, space
Exact sciences and technology
open clusters and associations: individual: Hyades
open clusters and associations: individual: Hyades, Praesepe
Praesepe
Spectrum analysis
Star & galaxy formation
Stars & galaxies
stars: rotation
Stellar rotation
surveys
techniques: photometric
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Summary:We present the results of photometric surveys for stellar rotation in the Hyades and in Praesepe, using data obtained as part of the SuperWASP exoplanetary transit-search programme. We determined accurate rotation periods for more than 120 sources whose cluster membership was confirmed by common proper motion and colour-magnitude fits to the clusters' isochrones. This allowed us to determine the effect of magnetic braking on a wide range of spectral types for expected ages of ∼600 Myr for the Hyades and Praesepe. Both clusters show a tight and nearly linear relation between J−K s colour and rotation period in the F, G and K spectral range. This confirms that loss of angular momentum was significant enough that stars with strongly different initial rotation rates have converged to the same rotation period for a given mass, by the ages of Hyades and Praesepe. In the case of the Hyades, our colour-period sequence extends well into the M dwarf regime and shows a steep increase in the scatter of the colour-period relation, with identification of numerous rapid rotators from ∼0.5 M⊙ down to the lowest masses probed by our survey (∼0.25 M⊙). This provides crucial constraints on the rotational braking time-scales and further clears the way to use gyrochronology as an accurate age measurement tool for main-sequence stars.
ISSN:0035-8711
1365-2966
DOI:10.1111/j.1365-2966.2011.18299.x