Stellar populations and mass loss in M15:: A Spitzer Space Telescope detection of dust in the intracluster medium

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 designated K648, and a possible detection of the intracluster medium arising from mass-loss episodes from the evolved stellar population. Our analysis suggests that (9 +/- 2) x 10(-4) M-circle dot of dust is present in the core of M15, and that this material has accumulated over a period of approximate to 10(6) yr, a timescale 10 times shorter than the last Galactic plane crossing event. We also present Spitzer IRS followup observations of K648, including the detection of the [Ne II] 12.81 mu m line, and discuss abundances derived from infrared fine-structure lines.