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Published August 1, 2010 | Published
Journal Article Open

Disks in the Arches Cluster—Survival in a Starburst Environment

Abstract

Deep Keck/NIRC2 HK'L' observations of the Arches cluster near the Galactic center reveal a significant population of near-infrared excess sources. We combine the L'-band excess observations with K'-band proper motions, which allow us to confirm cluster membership of excess sources in a starburst cluster for the first time. The robust removal of field contamination provides a reliable disk fraction down to our completeness limit of H = 19 mag, or ~5 M_⊙ at the distance of the Arches. Of the 24 identified sources with K' – L' > 2.0 mag, 21 have reliable proper motion measurements, all of which are proper motion members of the Arches cluster. VLT/SINFONI K'-band spectroscopy of 3 excess sources reveals strong CO bandhead emission, which we interpret as the signature of dense circumstellar disks. The detection of strong disk emission from the Arches stars is surprising in view of the high mass of the B-type main sequence host stars of the disks and the intense starburst environment. We find a disk fraction of 6% ± 2% among B-type stars in the Arches cluster. A radial increase in the disk fraction from 3% to 10% suggests rapid disk destruction in the immediate vicinity of numerous O-type stars in the cluster core. A comparison between the Arches and other high- and low-mass star-forming regions provides strong indication that disk depletion is significantly more rapid in compact starburst clusters than in moderate star-forming environments.

Additional Information

© 2010 The American Astronomical Society. Received 2009 November 6; accepted 2010 May 24; published 2010 July 7. Based on observations made with the Keck II telescope on Mauna Kea, Hawaii, and with ESO Telescopes at the Paranal Observatory under program ID 60.A-9026. This work would not have been possible without the intense effort and dedication of the Keck LGS-AO staff. We are deeply grateful for their support enabling these observations. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. A.S. acknowledges support by the German Science Foundation Emmy Noether program (STO 496/3-1). This work was supported by NSF grant AST 04-06816 and by the Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement AST 98-76783. Facilities: Keck:II (NIRC2), VLT:Yepun

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August 22, 2023
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