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The prevalence of star formation as a function of Galactocentric radius

Ragan, S. E., Moore, T. J. T., Eden, D. J., Hoare, M. G., Elia, D. and Molinari, S. 2016. The prevalence of star formation as a function of Galactocentric radius. Monthly Notices of the Royal Astronomical Society 462 (3) , pp. 3123-3129. 10.1093/mnras/stw1870

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We present large-scale trends in the distribution of star-forming objects revealed by the Hi-GAL survey. As a simple metric probing the prevalence of star formation in Hi-GAL sources, we define the fraction of the total number of Hi-GAL sources with a 70 μm counterpart as the `star-forming fraction' or SFF. The mean SFF in the inner galactic disc (3.1 kpc < RGC < 8.6 kpc) is 25 per cent. Despite an apparent pile-up of source numbers at radii associated with spiral arms, the SFF shows no significant deviations at these radii, indicating that the arms do not affect the star-forming productivity of dense clumps either via physical triggering processes or through the statistical effects of larger source samples associated with the arms. Within this range of Galactocentric radii, we find that the SFF declines with RGC at a rate of -0.026 ±0.002 per kiloparsec, despite the dense gas mass fraction having been observed to be constant in the inner Galaxy. This suggests that the SFF may be weakly dependent on one or more large-scale physical properties of the Galaxy, such as metallicity, radiation field, pressure or shear, such that the dense sub-structures of molecular clouds acquire some internal properties inherited from their environment.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Publisher: Oxford University Press
ISSN: 0035-8711
Date of First Compliant Deposit: 12 June 2017
Date of Acceptance: 26 July 2016
Last Modified: 05 May 2020 11:45

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