Discovery of long-period variable stars in the very metal-poor globular cluster M15

作者：McDonald I^*; van Loon J Th; Dupree A K; Boyer M L

来源：Monthly Notices of the Royal Astronomical Society, 2010, 405(3): 1711-1722.

DOI：10.1111/j.1365-2966.2010.16603.x

• stars: AGB and post-AGB
• stars: late-type
• stars: Population II
• stars: variables: general
• stars: winds, outflows
• globular clusters: individual: M15

We present a search for long-period variable (LPV) stars among giant branch stars in M15 which, at [Fe/H] similar to -2.3, is one of the most metal-poor Galactic globular clusters. We use multicolour optical photometry from the 0.6-m Keele Thornton and 2-m Liverpool Telescopes. Variability of delta V similar to 0.15 mag is detected in K757 and K825 over unusually long time-scales of nearly a year, making them the most metal-poor LPVs found in a Galactic globular cluster. K825 is placed on the long secondary period sequence, identified for metal-rich LPVs, though no primary period is detectable. We discuss this variability in the context of dust production and stellar evolution at low metallicity, using additional spectra from the 6.5-m Magellan (Las Campanas) telescope. A lack of dust production, despite the presence of gaseous mass loss raises questions about the production of dust and the intracluster medium of this cluster.

• 出版日期2010-7-1