ELFT HÍRADÓ

[Bence Kocsis <bkocsis AT caesar.elte.hu>]

*ELTE Astrophysics Seminar *

Tuesday, September 17, 15:00,
ELTE Pazmany Peter setany 1/A, room 3.139

*The accretion mechanisms in the protoplanetary discs*

*   Mohsen Shadmehri* (Golestan University)

The protoplanetary discs (PPDs) are known as sites of planet formation.
Mass of a PPD mostly consists of gas, however, dust particles also exist
with an abundance around one percent. While it was believed that
magnetorotational instability (MRI) is responsible for the mass accretion
in the PPDs, recent observational evidence and theoretical arguments
indicate that probably wind-driven accretion is dominant at least in the
inner disc region. Although this feature has raised intense investigations,
a big challenge is how to propose a robust diagnostic to discriminate the
dominant mechanism of the accretion in the PPDs. In this talk, I first
review the major mechanisms that generate PPDs turbulence. The most recent
observational diagnostics supporting the existence of efficient
magnetically wind-driven accretion are discussed. We then explore the
evolution of the PPDs in the presence of the magnetically driven winds and
the resulting isochrones tracks in the accretion rate and disc mass plane
are confronted with the observed PPDs. Evolutions of the disc quantities
such as its total mass and its radius are studied for different levels of
the magnetic wind strength. While previous studies based on the viscous
disc model were able to obtain isochrones tracks more or less consistent
with the observed PPDs, our more sophisticated disc model which
incorporates magnetic winds can also give us isochrones tracks consistent
with the observations. Our results thereby reinforce that role of the
magnetic winds cannot be neglected in PPDs.

Everyone is welcome!