سخنران: محسن شادمهری (دانشگاه گلستان) تاریخ برگزاری رویداد: دوشنبه ۱۱ اسفند ماه ۱۳۹۹

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.