MOST observations of the young open cluster NGC 2264^*

¹ Institut für Astronomie, Universität Wien, Türkenschanzstrasse 17, 1180 Vienna, Austria e-mail: zwintz@astro.univie.ac.at
² Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada e-mail: [kuschnig;matthews]@astro.ubc.ca; gordonwa@uvic.ca
³ Instituto de Astrofísica de Andalucía (CSIC), PO Box 3004, 18080 Granada, Spain e-mail: [pja;eloy;dario]@iaa.es
⁴ Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergässchen 2-3, 07740 Jena, Germany e-mail: pribulla@ta3.sk
⁵ Astronomical Institute of the Slovak Academy of Sciences, 05960 Tatranská Lomnica, The Slovak Republic
⁶ Department of Astronomy and Physics, St. Mary's University, Halifax, NS B3H 3C3, Canada e-mail: guenther@ap.smu.ca
⁷ Départment de physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7, Canada e-mail: moffat@astro.umontreal.ca
⁸ David Dunlap Observatory, University of Toronto, PO Box 360, Richmond Hill, ON L4C 4Y6, Canada e-mail: rucinski@astro.utoronto.ca
⁹ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA e-mail: sasselov@cfa.harvard.edu

Received: 17 February 2009
Accepted: 5 May 2009

Abstract

Context. Photometric time series obtained from space are one of the best ways to study pulsations in pre-main sequence (PMS) stars, especially as the corresponding amplitudes are at the millimagnitude level or below. We present high-precision time-series photometry of stars in the field of NGC 2264 obtained with the MOST (Microvariability & Oscillations of STars) satellite.

Aims. A search for pulsating A and F type members of NGC 2264 with ultra-precise MOST photometry was conducted.

Methods. 68 stars in the field of NGC 2264 were observed simultaneously with the MOST satellite, 34 of which were previously identified as potential targets to search for PMS pulsation. The routines SigSpec and Period04 were used for the frequency analysis.

Results. We discovered pulsation in 4 potential A and F type PMS members of NGC 2264 with frequencies between 2.7 h and 23 min. For one of the PMS pulsators identified with MOST after the first days of observation, simultaneous ground-based Strömgren photometry was obtained with the OSN 0.9 m telescope and confirms the highest frequency identified in the MOST photometry. 26 stars with other (i.e., hotter and cooler) spectral types show clear variability: SPB and γ Doradus pulsation, red giant oscillations, eclipsing binaries and variability caused by rotational modulation.