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Heart of Darkness: dust obscuration of the central stellar component in globular clusters younger than ~100Myr in multiple stellar population models

Longmore, SN (2015) Heart of Darkness: dust obscuration of the central stellar component in globular clusters younger than ~100Myr in multiple stellar population models. Monthly Notices of the Royal Astronomical Society, 448 (1). L62-L66. ISSN 0035-8711

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Abstract

To explain the observed anomalies in stellar populations within globular clusters, many globular cluster formation theories require two independent episodes of star formation. A fundamental prediction of these models is that the clusters must accumulate large gas reservoirs as the raw material to form the second stellar generation. We show that young clusters containing the required gas reservoir should exhibit the following observational signatures: (i) a dip in the measured luminosity profile or an increase in measured reddening towards the cluster centre, with Av >10mag within a radius of a few pc; (ii) bright (sub)mm emission from dust grains; (iii) bright molecular line emission once the gas is dense enough to begin forming stars. Unless the IMF is anomalously skewed towards low-mass stars, the clusters should also show obvious signs of star formation via optical emission lines (e.g. H_alpha) after the stars have formed. These observational signatures should be readily observable towards any compact clusters (radii of a few pc) in the nearby Universe with masses > 10^6 Msun and ages <100Myr. This provides a straightforward way to directly test globular cluster formation models which predict large gas reservoirs are required to form the second stellar generation. The fact that no such observational evidence exists calls into question whether such a mechanism happens regularly for YMCs in galaxies within a few tens of Mpc.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record; Longmore, S. N. (2015) Heart of Darkness: dust obscuration of the central stellar component in globular clusters younger than ~100Myr in multiple stellar population models, is available online at: http://dx.doi.org/10.1093/mnrasl/slu203 .
Uncontrolled Keywords: astro-ph.GA; astro-ph.GA
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 27 May 2015 08:47
Last Modified: 27 May 2015 08:47
DOI or Identification number: /10.1093/mnrasl/slu203
URI: http://researchonline.ljmu.ac.uk/id/eprint/398

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