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, D. Sasselov
During two weeks of nearly continuous optical photometry of the young open
cluster NGC 2244 obtained by the MOST satellite, we discovered two new 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 c/d) in GSC 00154-00785 and two (0.40 and 0.51 c/d) in GSC
00154-01871. These frequency ranges are consistent with g-modes of $\ell \leq
2$ excited in models of main-sequence or pre-main-sequence (PMS) stars of
masses 4.5 - 5 $M_{\odot}$ 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.
View original:
http://arxiv.org/abs/1110.4104
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