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From light to mass: accessing the initial and present-day Galactic globular cluster mass functions.

Authors :
Bonatto, C.
Bica, E.
Source :
Monthly Notices of the Royal Astronomical Society. Jun2012, Vol. 423 Issue 2, p1390-1396. 7p. 2 Charts, 3 Graphs.
Publication Year :
2012

Abstract

ABSTRACT The initial and present-day mass functions (ICMFs and PDMFs, respectively) of the Galactic globular clusters (GCs) are constructed based on their observed luminosities, the stellar evolution and dynamical mass-loss processes, and the mass-to-light ratio ( M/ L). Under these conditions, a Schechter-like ICMF is evolved for approximately a Hubble time and converted into a luminosity function (LF), which requires finding the values of five free parameters: the mean GC age (), the dissolution time-scale of a 105-M⊙ cluster (τ5), the exponential truncation mass () and two M/ L parametrizing constants. This is achieved by minimizing the residuals between the evolved and observed LFs, with the minimum residuals and realistic parameters obtained with M/ Ls that increase with luminosity (or mass). The optimum PMDFs indicate a total stellar mass of ∼4 × 107 M⊙ still bound to GCs, representing ∼15 per cent of the mass in clusters at the beginning of the gas-free evolution. The corresponding ICMFs resemble the scale-free MFs of young clusters and molecular clouds observed in the local Universe, while the PDMFs follow closely a lognormal distribution with a turnover at M⊙. For most of the GC mass range, we find an M/ L lower than usually adopted, which explains the somewhat low . Our results confirm that the M/ L increases with cluster mass (or luminosity), and suggest that GCs and young clusters share a common origin in terms of physical processes related to formation. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00358711
Volume :
423
Issue :
2
Database :
Academic Search Index
Journal :
Monthly Notices of the Royal Astronomical Society
Publication Type :
Academic Journal
Accession number :
76445507
Full Text :
https://doi.org/10.1111/j.1365-2966.2012.20963.x