Protostars and Planets VI, Heidelberg, July 15-20, 2013
Angular Momentum Evolution During Star and Planetary System Formation
Davies, Claire (University of St Andrews)
Greaves, Jane (University of St Andrews)
If all angular momentum contained within collapsing cores was conserved during star formation, proto-stars would reach break-up velocities before reaching the main-sequence. Therefore, methods by which proto-stars can lose angular momentum must exist. It may be possible for stellar angular momentum to be transferred from star to disc via stellar magnetic field lines through a process called magnetic braking. Alternatively, the stellar angular momentum may be lost from the star-disc system completely via stellar or disc winds. The proportion of lost stellar angular momentum that is retained within the circumstellar disc is important to studies of planetary system formation. An increase in disc angular momentum may cause a reduction in the disc surface density, often used as an indicator of a disc\'s ability to form planets.
We introduce the disc-to-stellar angular momentum ratio as an indicator of the angular momentum retained within the disc and present results following its evolution during the first ~1-2Myrs for two distinct regions, namely the Orion Nebula Cluster (ONC) and Taurus-Auriga. We make use of data available in the literature for our calculations. We find that the more dense environment of the ONC harbours smaller and less massive discs than the less dense Taurus-Auriga region. Additionally, within each individual region, older discs appear preferentially larger and less massive. Our results indicate that both environment and age are important factors in the angular momentum evolution of circumstellar discs.
Click here to view poster PDF