Star Formation
Star Formation
The lives of the stars a constant battle between gravity trying to pull the star's gas inwards and the pressure of the gas pushing outwards. The battle starts when gravity begins to collapse a small part of a cold, dusty interstellar gas cloud. As it falls in, the temperature at the core rises and the protostar flares into life as infrared source buried deep in the cloud. Eventually the collapse slows, hydrogen begins to fuse into helium, the star 'burns' through the surrounding gas, and the star finally settles into the life of a main sequence star.
Current research areas
Disks around Young Stars
Dramatic images taken in the infra-red reveal rings and disks of dust and gas swirling around newly-formed stars. The images, taken by Peter Tuthill, use optical interferometry on the Keck Telescope, currently the world's largest. See images and more information at Peter Tuthill's web page.
Astrophysical Masers hugging young massive stars
Methanol masers are very bright and widespread tracers of sites of on-going massive star-formation. We still do not understand how the most massive stars (above about 8 solar masses) continue to gather material after they begin their hydrogen fusion processes to become a fully-fledged star. The question is, how do the stars get rid of the vast amounts of energy generated, without rapidly blowing away the matter that is still accreting?
Lisa Harvey-Smith addresses this issue by studying the regions of warm molecular gas that surround nascent massive stars. These molecular clouds generate masers, which allow us to study the physical conditions, kinematics and often the magnetic fields within these star-forming regions. Studies of masers have revealed some very interesting structures, including bipolar molecular outflows and circumstellar disks, which are providing the basis for understanding how massive stars transport their energy. Combined with an understanding of the small-scale magnetic fields in these regions, it is hoped that a thorough understanding of regions of massive star-formation can be reached.
mm Observations of Star Formation
The recently-upgraded Mopra antenna of the Australia Telescope National Facility is being used in two major surveys of how star formation happens. In our local Galactic neighbourhood, stars like are Sun are slowly forming in dark, cold, dense 'molecular clouds', where gravity can overwhelm the weak thermal pressure at temperatures only 10 degrees above absolute zero. The Spitzer Legacy Project From Cores To Disks (C2D) is a uniform look at over 100 of these protostars, with the aim of deciphering the common features and physical processes involved in making Sun-like stars and solar systems like our own. Peter Barnes has joined the C2D team using Mopra to complete the southern hemisphere 3mm-spectroscopy portion of this survey.
Mopra's pioneering capabilities are also the crucial component of the Census of High- and Medium-mass Protostars. This project looks over a large portion of the Milky Way in order to understand how more massive stars, which form faster in a more violent environment, are assembled and impact their surroundings. With partners from Japan and the Anglo-Australian Telescope, Peter Barnes is leading this multi-year project.
For more information contact Peter Barnes
Star Formation in nearby face-on spiral galaxies
Building on earlier work, an Honours thesis by Madhura Killedar, supervised by John O'Byrne focussed on a pixel-by-pixel comparison of UV and H-alpha images of several nearby face-on spiral galaxies. The flux between these two bands can be compared with model predictions to yield estimates of the age of star formation tracing out the spiral pattern. For more information see Star Formation in nearby Galaxies.