Journal Article

New slowly pulsating B stars in the field of the young open cluster NGC 2244 discovered by the <i>MOST</i> photometric satellite

D. Gruber, H. Saio, R. Kuschnig, L. Fossati, G. Handler, K. Zwintz, W. W. Weiss, J. M. Matthews, D. B. Guenther, A. F. J. Moffat, S. M. Rucinski and D. Sasselov

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 420, issue 1, pages 291-298
Published in print February 2012 | ISSN: 0035-8711
Published online January 2012 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2011.20033.x
New slowly pulsating B stars in the field of the young open cluster NGC 2244 discovered by the MOST photometric satellite

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During two weeks of nearly continuous optical photometry of the young open cluster NGC 2244 obtained by the Microvariability and Oscillations of STars (MOST) satellite, we discovered two new slowly pulsating B (SPB) stars, GSC 00154−00785 and GSC 00154−01871. We present frequency analyses of the MOST light curves of these stars, which reveal two oscillation frequencies (0.61 and 0.71 cycle d−1) in GSC 00154−00785 and two (0.40 and 0.51 cycle d−1) in GSC 00154−01871. These frequency ranges are consistent with g modes of ℓ≤ 2 excited in models of main-sequence or pre-main-sequence (PMS) stars of masses 4.5–5 M and solar composition (X, Z) = (0.7, 0.02). Published proper motion measurements and radial velocities are insufficient to establish unambiguously cluster membership for these two stars. However, the PMS models which fit best their eigenspectra have ages consistent with NGC 2244. If cluster membership can be confirmed, these would be the first known PMS SPB stars, and would open a new window on testing asteroseismically the interior structures of PMS stars.

Keywords: stars: early-type; stars: individual: GSC 00154−00785; stars: individual: GSC 00154−01871; stars: oscillations; stars: pre-main-sequence; open clusters and associations: individual: NGC 2244

Journal Article.  5056 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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