casca2017_pbarmby.pdf (1.66 MB)
Deconstructing M83: colours of point sources in a nearby galaxy
Poster presented at 2017 Canadian Astronomical Society meeting. Abstract:
Thousands of individual sources are detected in multi-band imaging observations of even a fraction of a nearby galaxy. This work analyzes a ten-band photometric catalog of nearly 70 000 point sources in Messier 83, made as part of the Early Release Science program with HST's WFC3. Two and three dimensional colour spaces were generated using various combinations of four bands and clustered with the K-Means and Mean Shift algorithms. Neither algorithm was able to consistently segment the colour distributions; however K-Means clustering of the UBVI colour space was able to identify a group of objects more likely to be star clusters and Mean Shift was successful in identifying outlying groups at the edges of colour distributions. The 10% of sources detected in all 10 bands were found to differ from each other most strongly in the ultraviolet and blue bands.
Thousands of individual sources are detected in multi-band imaging observations of even a fraction of a nearby galaxy. This work analyzes a ten-band photometric catalog of nearly 70 000 point sources in Messier 83, made as part of the Early Release Science program with HST's WFC3. Two and three dimensional colour spaces were generated using various combinations of four bands and clustered with the K-Means and Mean Shift algorithms. Neither algorithm was able to consistently segment the colour distributions; however K-Means clustering of the UBVI colour space was able to identify a group of objects more likely to be star clusters and Mean Shift was successful in identifying outlying groups at the edges of colour distributions. The 10% of sources detected in all 10 bands were found to differ from each other most strongly in the ultraviolet and blue bands.
