Prof Mark Thompson’s PhD projects

Please contact Prof Thompson directly if you are interested in this projects.

Unusual solar systems with massive debris disks

Debris disks are dusty disks of material around main sequence stars, revealed by their far-infrared excess emission. Collisions between asteroids or Kuiper Belt Objects generate small dust particles which absorb starlight from their host stars and reradiate this in the far-IR. Usually the amounts of dust in typical solar systems are very low, on the order of a few Lunar masses or less, however this may be an observational limitation of current debris disk surveys which are tightly focused on solar system analogues. We pioneered a new technique to identify debris disks in far-IR galaxy surveys (Thompson et al 2010: https://ui.adsabs.harvard.edu/abs/2010A%26A…518L.134T/abstract) which uncovered hints of a more massive and colder population of disks than previously known (with the prototypical candidate disk having roughly an Earth mass of dust). This PhD project is to study the sample of ~400 candidate disks that we have identified in the Herschel-ATLAS survey, using the GAIA DR2 release to determine the distance to these stars and the mass of the disks. You will also use GAIA data to extend the search from the Herschel-ATLAS survey to the entire Herschel legacy catalogue that covers about 10% of the sky. The results of this search will be used to select a sample of disks for high resolution observations with ALMA.

Massive Star Formation in the outer reaches of the Milky Way

Most surveys of our Milky Way galaxy are focused on the inner third of the Milky Way’s disk as this is the most cost effective way to search the volume of the Milky Way for massive star formation. The “outer reaches” of the Milky Way located outside the Sun’s orbit have not been well-studied due to the larger areas of sky that need to be mapped and the lower density of star forming regions there. However, this neglects the importance of the low metallicity regions in the Outer Galaxy as potential analogues for star formation in the earlier Universe. In this project you will take advantage of two recent sub-millimetre surveys (SASSy and SASSy-Perseus) to create a definitive atlas of the star formation in the outer reaches of the Milky Way. You will use archival molecular spectroscopy to determine the distance to these regions, search for signs of embedded star formation using the JVLA telescope and archival data, and determine the star formation rate for these regions. This will create a valuable dataset with which to compare to the ATLASGAL studies of the inner Milky Way (Urquhart et al 2018: https://ui.adsabs.harvard.edu/abs/2018MNRAS.473.1059U/abstract) and resolved studies of nearby galaxies (e.g. M31, Forbrich et al 2020: https://ui.adsabs.harvard.edu/abs/2020ApJ…890…42F/abstract). Our eventual aim is to determine a physical relationship between the properties of molecular gas and the resulting massive star formation, which can then be used to interpret unresolved high redshift studies.