From planet formation to thermodynamic constraints on the first genetic code
Ralph Pudritz
McMaster University

Protoplanetary disks provide the initial conditions for planet formation as well as for their prebiotic states. In this talk I will examine both aspects of planetary formation.

Standard models for planet formation in dusty, gaseous disks reveal that planets rapidly migrate from their birth positions. This process is so efficient that planets risk plunging into their central stars within a million years. I shall review observations and ideas of what controls the process of exoplanet formation and migration. I will then present our recent simulations of migrating and accreting planets in radiatively heated protostellar disks containing dead zones - regions where turbulence is strongly suppressed. We have discovered that both the density and thermal structure of disks with such regions act as effective brakes that prevent the rapid loss of planets to their central stars.

The radiatively heated natal disks that produce planets may also be significant factories for the synthesis of biomolecules such as amino acids, which may be delivered to planets by cometary or meteoritic bombardment. This is a very significant aspect of astrobiology. We have recently discovered some general thermodynamic constraints on the synthesis of amino acids in a variety of prebiotic environments. This provides insight into the environments which produced biomolecules for early life and possible constraints on the nature of the first genetic code.

Date:	Jeudi, le 1 octobre 2009
Heure:	11:30
Lieu:	Université de Montréal
	Pavillon Roger-Gaudry, Local D-460
Contact:	Marie-Ève Naud