Calibrating SkyMapper and the local density of white dwarfs

White Dwarfs are the end points of the evolution of stars like the Sun.  The numbers of such stars, their masses and their kinematics are capable of revealing information on subjects as diverse as stellar evolution and mass loss processes and the age of the Galaxy's disk.  The northern hemisphere sky has been searched for white dwarfs using the Sloan Digital Sky Survey but a complete survey of the southern hemisphere sky for white dwarfs is currently lacking.

The SkyMapper southern sky survey, however, provides the ideal way to redress the situation.  The survey is being conducted with The Australian National University's SkyMapper telescope at Siding Spring Observatory and the survey filter system has been specially designed to allow determination of fundamental stellar parameters such as surface temperature and surface gravity.  White dwarf stars, because of their solar-like masses but small radii, have very high surface gravities and are readily distinguishable in the SkyMapper gravity-sensitive 2-colour diagram.

In this project you will work with members of the SkyMapper team to assist in the fundamental calibration of the SkyMapper photometry system and then use the calibrated photometry to isolate candidate white dwarf stars.  A subset will be followed-up spectroscopically with the 2.3m telescope at Siding Spring to confirm the classification, though it is expected that the SkyMapper gravity-based selection should have minimal contamination.  Subsequent work can then cover subjects from constraints on the initial mass to final mass relation (i.e. what is the maximum mass on the main sequence a star can have and still end up as a white dwarf) from the hottest white dwarfs in the sample, to constrains on the age of the Galactic disk from the luminosity function of coolest white dwarfs.

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