English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We use HST/ACS observations of the spiral galaxy M51 in F435W, F555W andF814W to select a large sample of star clusters with accurate effective radiusmeasurements in an area covering the complete disc of M51. We present thedataset and study the radius distribution and relations between radius, colour,arm/interarm region, galactocentric distance, mass and age. We select a sampleof 7698 (F435W), 6846 (F555W) and 5024 (F814W) slightly resolved clusters andderive their effective radii by fitting the spatial profiles with analyticalmodels convolved with the point spread function. The radii of 1284 clusters arestudied in detail. We find cluster radii between 0.5 and ~10 pc, and oneexceptionally large cluster candidate with a radius of 21.6 pc. The medianradius is 2.1 pc. We find 70 clusters in our sample which have coloursconsistent with being old GC candidates and we find 6 new "faint fuzzy"clusters in, or projected onto, the disc of M51. The radius distribution cannot be fitted with a power law, but a log-normal distribution provides areasonable fit to the data. This indicates that shortly after the formation ofthe clusters from a fractal gas, their radii have changed in a non-uniform way.We find an increase in radius with colour as well as a higher fraction ofredder clusters in the interarm regions, suggesting that clusters in spiralarms are more compact. We find a correlation between radius and galactocentricdistance which is considerably weaker than the observed correlation for oldMilky Way GCs. We find weak relations between cluster luminosity and radius,but we do not observe a correlation between cluster mass and radius.

ACS imaging of star clusters in M51. I. Identification and radius distribution