ProfessorSimon Ellingsen

Expertise

Simon is an expert in astronomy/astrophysics, in particular radio astronomy and very long baseline interferometry.

Research Themes

Simon's primary research interest is in the study of the formation of the largest stars in our galaxy (known as high-mass stars), particularly through radio astronomy observations of methanol masers. High-mass stars form in regions of dense gas and dust which completely obscures them from view at optical wavelengths. Fortunately, radio frequency radiation passes through the gas and dust unhindered. Interstellar masers are naturally occurring radio frequency lasers, which are often associated with newly formed large stars. The fundamental aim of his work is to measure the physical conditions, such as temperature, density and pressure around from observations of the masers in order to understand important questions such as how planets form. Work he has undertaken using the presence/absence of various interstellar maser species/transitions as an evolutionary clock for high-mass star formation regions has provided new insights over recent years.

Simon is the lead investigator of a large project which has used the Australian Long Baseline Array and is now using an array of University of Tasmania radiotelescopes to make trigonometric parallax measurements towards maser sources in southern high-mass star formation regions to trace the spiral structure of the southern Milky Way.

Simon has also used observations of methanol emission and absorption to test whether some of the fundamental constants of physics have changed over the lifetime of the Universe. In particular, observations of absorption in two different rotational transitions of the methanol molecule in the gravitational lens system PKS B1830-211 have shown that the ratio of the mass of the proton to the mass of the electron has changed by less than 1 part in 10 million over the last 7.2 billion years. In 2014 he detected the first class I methanol masers outside the Milky Way, towards the starburst galaxy NGC253 and these objects are providing new insights into why some galaxies have large bursts of star formation.

Collaboration

The University of Tasmania’s radiotelescopes have been used to support a range of scientific and commercial space missions. Simon is working in collaboration with the Australian Space Agency to improve Australia’s capability to support space missions. This includes the construction of a new dedicated satellite tracking antenna at the University of Tasmania’s Greenhill observatory at Bisdee Tier in the southern-midlands of Tasmania.

Awards

2009-2010 Alexander von Humboldt Experienced Researcher Fellowship at the Max-Planck Institut für Radioastronomie, Bonn, Germany
2007 Co-Investigator on VRAD experiment as part of SELENE (Japanese Lunar) mission
2003 Engineering Excellence Award, Engineers Australia
2002 Research Excellence Award, Faculty of Science and Technology, University of Tasmania
1999 Royal Society of Tasmania, New Doctoral Award

Current projects

Simon is the principal investigator for a large (600 hour) project being undertaken with the Australian Long Baseline Array and the University of Tasmania’s AuScope array to measure accurate distances to star formation regions in the Southern Milky Way. This project is a collaboration between scientists in Australian, USA, Germany, Japan, China and South Africa who are seeking to obtain the most accurate picture to date of the structure of our Galaxy.

Simon is collaborating with astronomers at the Shanghai Observatory (China) to investigate the recently discovered phenomenon of class I methanol megamasers. We discovered the first extragalactic class I methanol masers in 2014 and found that they arise in regions where there are large-scale, low-velocity shocks. We followed this up with the detection of the first HC3N (cyanoacetlyene) masers in 2017. We think that these masers will be a new and powerful means to study star formation and feedback processes in starburst galaxies (galaxies where star formation is occurring at a much greater rate than it does in normal spiral galaxies like the Milky Way).