Volume 560, December 2013
|Number of page(s)||25|
|Section||Galactic structure, stellar clusters and populations|
|Published online||28 November 2013|
The Monitor Project: stellar rotation at 13 Myr
UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de
Grenoble (IPAG) UMR 5274,
2 Crimean Astrophysical Observatory, p/o Nauchny, 98409 Crimea, Ukraine
3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA
4 Ulugh Bek Astronomical Institute of the Uzbek Academy of Sciences, Astronomicheskaya 33, 700052 Tashkent, Uzbekistan
5 Byurakan Astrophysical Observatory, 0213 Aragatsotn reg., Armenia
6 Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese, Italy
7 Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
8 Astrophysics, Denys Wilkinson Building, University of Oxford, Oxford OX1 3RH, UK
Accepted: 18 June 2013
Aims. We aim at constraining the angular momentum evolution of low-mass stars by measuring their rotation rates when they begin to evolve freely towards the zero-age main sequence (ZAMS), i.e., after the disk accretion phase has stopped.
Methods. We conducted a multisite photometric monitoring of the young open cluster h Persei, which has an age of ~13 Myr. The observations were done in the I-band using four different telescopes, and the variability study is sensitive to periods from less than 0.2 day to 20 days.
Results. Rotation periods are derived for 586 candidate cluster members over the mass range 0.4 ≤ M/M⊙ ≤ 1.4. The rotation period distribution indicates a slightly higher fraction of fast rotators for the lower mass objects, although the lower and upper envelopes of the rotation period distribution, located respectively at ~0.2–0.3 d and ~10 d, are remarkably flat over the whole mass range. We combine this period distribution with previous results obtained in younger and older clusters to model the angular momentum evolution of low mass stars during the pre-main sequence (PMS) phase.
Conclusions. The h Per cluster provides the first statistically robust estimate of the rotational period distribution of solar-type and lower mass stars at the end of the PMS accretion phase (≥10 Myr). The results are consistent with models that assume significant core-envelope decoupling during the angular momentum evolution to the ZAMS.
Key words: stars: rotation / stars: low-mass / open clusters and associations: individual: h Per
Based on observations made with telescopes at the Maidanak Observatory, at the Crimean Astrophysical Observatory, at the Byurakan Observatory, and with MegaPrime/MegaCam on the Canada-France-Hawaii Telescope (CFHT).
Appendix A is available in electronic form at http://www.aanda.org
The list of periodic objects including periods and photometric measurements (Table 2) is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A13
© ESO, 2013
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