Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-26T07:26:42.815Z Has data issue: false hasContentIssue false
  • English
  • Français

A nonlinear model for rotating cool stars

Published online by Cambridge University Press:  26 August 2011

Sydney A. Barnes
Sydney A. Barnes*
Affiliation:
Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff, AZ 86001, USA email: barnes@lowell.edu
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

A simple nonlinear model is introduced here to describe the rotational evolution of main sequence cool (FGKM) stars. It is formulated only in terms of the ratio of a star's rotation period, P, to its convective turnover timescale, τ, and two dimensionless constants which are specified using solar- and open cluster data. The model explains the origin of the two sequences, C/fast and I/slow, of rotating stars observed in open cluster color-period diagrams, and describes their evolution from C-type to I-type through the rotational gap, g, separating them. It explains why intermediate-mass open cluster stars have the longest periods, while higher- and lower-mass cool stars have shorter periods. It provides an exact expression for the age of a rotating cool star in terms of P and τ, thereby generalizing gyrochronology. The possible range of initial periods is shown to contribute upto 128 Myr to the gyro age errors of solar mass field stars. A transformation to color-period space shows how this model explains some detailed features in the color-period diagrams of open clusters, including the shapes and widths of the sequences, and the observed number density of stars across these diagrams.

Keywords

Convection, methods: analyticalstars: evolutionstars: late-typestars: rotation
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S273: The Physics of Sun and Star Spots , August 2010 , pp. 465 - 468
Copyright
Copyright © International Astronomical Union 2011

References

Barnes, S. A., 2003, Astrophys. J., 586, 464CrossRefGoogle Scholar
Barnes, S. A., 2007, Astrophys. J., 669, 1167CrossRefGoogle Scholar
Barnes, S. A., 2010, Astrophys. J., in pressGoogle Scholar
Barnes, S. A. & Kim, Y.-C., 2010, Astrophys. J., in pressGoogle Scholar
Chaboyer, B., Demarque, P. D., & Pinsonneault, M. H., 1995,Astrophys. J., 441, 876CrossRefGoogle Scholar
Hartman, J. D., Bakos, G. A., Kovacs, G., & Noyes, R. W., 2010, Mon. Not. Roy. Astron. Soc., in pressGoogle Scholar
Hartman, J. D., Gaudi, B. S., Pinsonneault, M. H., Stanek, K. Z., Holman, M. J., McLeod, B. A., Meibom, S., Barranco, J. A., & Kalirai, J. S., 2009, Astrophys. J., 691, 342CrossRefGoogle Scholar
Kawaler, S. D., 1988, Astrophys. J., 333, 236CrossRefGoogle Scholar
MacGregor, K. B. & Brenner, M., 1991, Astrophys. J., 376, 204CrossRefGoogle Scholar
Meibom, S., Mathieu, R. D., & Stassun, K. G., 2009, Astrophys. J., 695, 679CrossRefGoogle Scholar
Mestel, L., 1968, Mon. Not. Roy. Astron. Soc., 138, 359CrossRefGoogle Scholar
Noyes, R. W., Hartmann, L. W., Baliunas, S. L., Duncan, D. K., &, Vaughan, A. H., 1984, Astrophys. J., 279, 763CrossRefGoogle Scholar
Parker, E. N., 1958, Astrophys. J., 128, 664CrossRefGoogle Scholar
Radick, R. R., Skiff, B. A., & Lockwood, G. W., 1990, Astrophys. J., 353, 524CrossRefGoogle Scholar
Radick, R. R., Thompson, D. T., Lockwood, G. W., Duncan, D. K., & Baggett, W. E., 1987, Astrophys. J., 321, 459CrossRefGoogle Scholar
Schatzman, E., 1962, Annales d'Astrophysique, 25, 18Google Scholar
Skumanich, A., 1972, Astrophys. J., 171, 565CrossRefGoogle Scholar
Weber, E. J. & Davis, L. L., 1967, Astrophys. J., 148, 217CrossRefGoogle Scholar