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The spatial relation between young star clusters and molecular clouds in M51 with LEGUS

Grasha, K; Calzetti, D; Adamo, A; Kennicutt, RC; Elmegreen, BG; Messa, M; Dale, DA; Fedorenko, K; Mahadevan, S; Grebel, EK; Fumagalli, M; Kim, H; Dobbs, CL; Gouliermis, DA; Ashworth, G; Gallagher, JS; Smith, LJ; Tosi, M; Whitmore, BC; Schinnerer, E; Colombo, D; Hughes, A; Leroy, AK; Meidt, SE

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K Grasha

D Calzetti

A Adamo

RC Kennicutt

BG Elmegreen

M Messa

DA Dale

K Fedorenko

S Mahadevan

EK Grebel

H Kim

CL Dobbs

DA Gouliermis

G Ashworth

JS Gallagher

LJ Smith

M Tosi

BC Whitmore

E Schinnerer

D Colombo

A Hughes

AK Leroy

SE Meidt


We present a study correlating the spatial locations of young star clusters with those of molecular clouds in NGC 5194, in order to investigate the time-scale over which clusters separate from their birth clouds. The star cluster catalogues are from the Legacy ExtraGalactic UV Survey (LEGUS) and the molecular clouds from the Plateau de Bure Interefrometer Arcsecond Whirpool Survey (PAWS). We find that younger star clusters are spatially closer to molecular clouds than older star clusters. The median age for clusters associated with clouds is 4 Myr, whereas it is 50 Myr for clusters that are sufficiently separated from a molecular cloud to be considered unassociated. After ∼6 Myr, the majority of the star clusters lose association with their molecular gas. Younger star clusters are also preferentially located in stellar spiral arms where they are hierarchically distributed in kpc-size regions for 50–100 Myr before dispersing. The youngest star clusters are more strongly clustered, yielding a two-point correlation function with α = −0.28 ± 0.04, than the giant molecular cloud (GMCs) (α = −0.09 ± 0.03) within the same PAWS field. However, the clustering strength of the most massive GMCs, supposedly the progenitors of the young clusters for a star formation efficiency of a few per cent, is comparable (α = −0.35 ± 0.05) to that of the clusters. We find a galactocentric dependence for the coherence of star formation, in which clusters located in the inner region of the galaxy reside in smaller star-forming complexes and display more homogeneous distributions than clusters further from the centre. This result suggests a correlation between the survival of a cluster complex and its environment.


Grasha, K., Calzetti, D., Adamo, A., Kennicutt, R., Elmegreen, B., Messa, M., …Meidt, S. (2019). The spatial relation between young star clusters and molecular clouds in M51 with LEGUS. Monthly Notices of the Royal Astronomical Society, 483(4), 4707-4723.

Journal Article Type Article
Acceptance Date Dec 13, 2018
Online Publication Date Dec 19, 2018
Publication Date Mar 11, 2019
Deposit Date Mar 14, 2019
Publicly Available Date Mar 14, 2019
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 483
Issue 4
Pages 4707-4723


Published Journal Article (17.9 Mb)

Copyright Statement
© 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.

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