Clearing the Dust from Globular Clusters

• Published in: The Astrophysical journal Vol. 680; no. 2; pp. L113 - L116
• Main Authors: Umbreit, Stefan, Chatterjee, Sourav, Rasio, Frederic A
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 20.06.2008; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Shock waves; blue stragglers-globular clusters: general-globular clusters: individual (M15); Blue stragglers; Stellar mass; Mass loss; Globular clusters; Star clusters; stars: mass loss; Stellar dynamics
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1086/590080

Recent Spitzer observations of the globular cluster M15 detected dust associated with its intracluster medium. Surprisingly, these observations imply that the dust must be very short-lived compared to the time since the last Galactic plane crossing of the cluster. Here we propose a simple mechanism to explain this short lifetime. We argue that the kinetic energy of the material ejected during a stellar collision may be sufficient to remove the gas and dust entirely from a cluster, or to remove the gas as a wind, in addition to partially destroying the dust. By calculating the rate of stellar collisions using an N-body model for the cluster, we find remarkable agreement between the average time between collisions and the inferred dust lifetime in this cluster, suggesting a possible close relation between the two phenomena. Furthermore, we also obtain the birthrate of blue stragglers formed through collisions in M15. By comparing with the observed number of blue stragglers, we derive an upper limit for their average lifetime that turns out to be consistent with recent model calculations, thereby lending further support to: our model.