Name: Vera Jatenco-Pereira

Institution: IAG/USP

e-mail: jatenco@astro.iag.usp.br

Partner Contry: BRA

Science Meeting: Yes

User Meeting: Yes

NGO Staff Meeting: No

Presentation: Yes

Format: Poster

Title: An non-thermal heating source in protostellar disks

Co-author: A. A. Vidotto & V. Jatenco-Pereira

Co-authors' Institutions: IAG/USP

Abstract:

In order to accrete material from the disk, the disk particles that surround a protostar must lose their angular momentum. The magneto-rotational instability (MRI) is the most accepted mechanism. However, this mechanism only exists if the gas in the disk is sufficiently ionized to be coupled to the magnetic field. In this work we study, besides the viscous heating mechanism,the damping of Alfv?n waves as an additional heating source. As disks are composed by charged dust grains, the propagation of the waves will be affected. In particular, the Alfv?n waves will sufer a damping near the dust-cyclotron frequency, since charged grains in a magnetized medium are highly coupled to the waves due to cyclotron resonances. We assume a size distribution for the grains which implies different charges and thus a broad band of resonance frequencies. We show that the damping of the waves can increase the temperature of the disk which lead to an increase on the ionization fraction making the MRI operate in a large part of the disk.

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