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Stellar Populations and Mass-Loss in M15: A Spitzer Detection of Dust in the Intra-Cluster Medium

Martha L. Boyer·Charles E. Woodward·Jacco Th. van Loon·Karl D. Gordon·A. Evans·Robert D. Gehrz·L. A. Helton·Elisha F. Polomski
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Abstract

We present Spitzer Space Telescope IRAC and MIPS observations of the galactic globular cluster M15 (NGC 7078), one of the most metal-poor clusters with a [Fe/H] = -2.4. Our Spitzer images reveal a population of dusty red giants near the cluster center, a previously detected planetary nebula (PN) designated K648, and a possible detection of the intra-cluster medium (ICM) arising from mass loss episodes from the evolved stellar population. Our analysis suggests 9 (+/-2) x 10^-4 solar masses of dust is present in the core of M15, and this material has accumulated over a period of approximately 10^6 years, a timescale ten times shorter than the last galactic plane crossing event. We also present Spitzer IRS follow up observations of K648, including the detection of the [NeII] 12.81 micron line, and discuss abundances derived from infrared fine structure lines.

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Martha L. Boyer, Charles E. Woodward, Jacco Th. van Loon, Karl D. Gordon, A. Evans, Robert D. Gehrz, L. A. Helton, Elisha F. Polomski. 2006-06-09. Stellar Populations and Mass-Loss in M15: A Spitzer Detection of Dust in the Intra-Cluster Medium. https://doi.org/10.1086/506518

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