A SPITZER SEARCH FOR COLD DUST WITHIN GLOBULAR CLUSTERS

作者：Barmby Pauline^*; Boyer Martha L; Woodward Charles E; Gehrz Robert D; van Loon Jacco Th; Fazio Giovanni G; Marengo Massimo; Polomski Elisha

来源：Astronomical Journal, 2009, 137(1): 207-217.

DOI：10.1088/0004-6256/137/1/207

• globular clusters: general
• globular clusters: individual (NGC 104, NGC 362, NGC 1851, NGC 5272, NGC 5904, NGC 6205, NGC 6341, NGC 6752)
• infrared: stars
• stars: mass loss

Globular cluster (GC) stars evolving off the main sequence are known to lose mass, and it is expected that some of the lost material should remain within the cluster as an intracluster medium (ICM). Most attempts to detect such an ICM have been unsuccessful. The Multiband Imaging Photometer for Spitzer on the Spitzer Space Telescope was used to observe eight Galactic GCs in an attempt to detect the thermal emission from ICM dust. Most clusters do not have significant detections at 70 mu m; one cluster, NGC 6341, has tentative evidence for the presence of dust, but 90 mu m observations do not confirm the detection. Individual 70 mu m point sources which appear in several of the cluster images are likely to be background galaxies. The inferred dust mass and upper limits are less than 4 x 10(-4) M(circle dot), well below expectations for cluster dust production from mass loss in red and asymptotic giant branch stars. This implies that either GC dust production is less efficient, or that ICM removal or dust destruction is more efficient, than previously believed. We explore several possibilities for ICM removal and conclude that present data do not yet permit us to distinguish between them.

• 出版日期2009-1