William Harris
William Harris
Professor Emeritus
ABB 316

William Harris and The Big Picture

William Harris 640x192My main research interests are in the earliest stages of galaxy evolution -- the first few Gigayears of a galaxy's history during which structures like its halo stars and globular clusters emerged.  Their properties yield unique clues to the most active part of galaxy formation.  See my webpage for more, but here's a shortlist of projects I'm currently involved with:

  • Hubble Space Telescope imaging of a series of supergiant elliptical galaxies in the cosmologically "nearby" universe at distances from 40 to 200 Megaparsecs.  These giants have the largest globular cluster populations known (tens of thousands of clusters per galaxy) and with this data, our team is building up the biggest photometric database for globular clusters in existence.  With this material we are exploring patterns in the distributions of globular cluster luminosity, heavy-element enrichment, and spatial distributions in their galaxy halos -- all of which are tracers of their formation epoch.
  • Correlations between globular cluster populations and other large-scale properties of their host galaxies, including dynamical mass, galaxy type, and (very puzzlingly) their central supermassive black holes.
  • Dynamics and assembly history of groups of galaxies over the redshift range z=0 to 1.
  • Photometry and modelling of the halo-star populations in nearby galaxies such as M33, NGC 5128, and M87.
  • Developing hydrodynamic modelling for the formation of massive star clusters.  The formation stage of "true" globular clusters (in the mass range of 0.1 to 10 million Solar masses) from their parent molecular clouds is the least well understood, but also most crucial, stage in their histories, and is likely to have produced important feedback on the larger-scale star formation history of the entire galaxy.
Globular clusters, stellar populations, evolution of galaxies
Dear Student,

I work in observational astronomy, particularly on nearby galaxies and star clusters. I especially like investigating the very oldest types of stars in galaxies, especially ones that are found in globular clusters and galactic halos. These objects give us a unique way of tracing what happened to the galaxies during their first, crucial formation period 10 to 12 billion years ago. In astrophysical terms, this is a route to connecting the detailed predictions from cosmological model theory to the real universe that we cannot do in any other way.

My students and colleagues get involved, like me, in analyzing and interpreting the raw data that we obtain from observatories like the Hubble Space Telescope, the Canada-France-Hawaii Telescope (CFHT), and the Gemini telescopes in Chile and Hawaii.  Travel to take part in astronomical society meetings and professional conferences is also an expected part of your educational experience here. You'll find that modern astronomy is a thoroughly international subject right from the start -- and one that Canada is an integral part of.

Our astrophysics group at McMaster is a very close-knit one. We work together. I welcome shared supervisions, such as with one of our theorists so that both observation and modelling can be carried out effectively. See my webpage for more, and please contact me at harris@physics.mcmaster.ca if you think this is a research area you might be interested in. This is a great group to be part of!

Bill Harris
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McMaster University - Faculty of Science | Physics & Astronomy