BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Dust dynamics in self-gravitating disks – could planet formation start in young disks? DTSTART;VALUE=DATE-TIME:20200514T144500Z DTEND;VALUE=DATE-TIME:20200514T150500Z DTSTAMP;VALUE=DATE-TIME:20241101T160712Z UID:indico-contribution-4-70@meetings.aip.de DESCRIPTION:Speakers: George Mamatsashvili (Helmholtz-Zentrum Dresden-Ross endorf)\nI will present the results on the evolution of dust particles in self-gravitating disks residing in a gravitoturbulent state\, when heating due to shocks of density waves balances cooling. It is well known that d ensity structures in the gaseous component of the disk induced by self-gra vity (gravitational instability) can trap dust efficiently enough\, so tha t the dust component itself undergoes further gravitational collapse due t o its own self-gravity. Previous results both in global and local shearing box studies indicate that over-pressure regions related to spiral density waves can be very efficient at collecting dust particles\, creating signi ficant local over-densities of particles. The degree of such concentration s depends on two parameters: the size of dust particles and the rate of ga s cooling. In recent years\, increasing observational evidence indicates t hat large-scale vortices (e.g.\, induced by planetary gaps) and rings are most preferable sites of dust trapping. \n\nMotivated by this\, we studied effects of vortices on the evolution of dust particles using local sheari ng box simulations of self-gravitating protoplanetary disks\, including al so the dust-back reaction on gas and self-gravity of the dust component it self. In contrast to non-self-gravitating disks\, vortices in self-gravita ting disks tend to be smaller-scale (of the order of local Jeans scale) an d short-lived structures. We found that these types of structures are neve rtheless quite efficient at trapping small and intermediate-sized dust par ticles with friction times comparable to\, or less than\, the local orbita l period of the disk. This can lead to significant over-densities in the s olid component of the disk\, with density enhancements comparable to\, and even higher\, than those within spiral density waves\; increasing the rat e of gravitational collapse of dust into bound structures (planetesimals). I will also discuss the resulting surface density structure of dust trapp ed in such vortices in connection with recent observations of disks.\n\nht tps://iaus379.aip.de/event/1/contributions/70/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://iaus379.aip.de/event/1/contributions/70/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthetic ALMA emission of massive protostellar discs. DTSTART;VALUE=DATE-TIME:20200514T142000Z DTEND;VALUE=DATE-TIME:20200514T144000Z DTSTAMP;VALUE=DATE-TIME:20241101T160712Z UID:indico-contribution-4-35@meetings.aip.de DESCRIPTION:Speakers: Dominique Meyer (University of Potsdam)\nMassive pro tostellar discs are the sibling circumstellar structures of protoplanetary accretion discs. They form\, evolve as a scaled-up version of the surrou ndings of low-mass stars and both formation mechanisms are unified within the so-called burst mode of star formation. This picture naturally links t he development of gravitational instabilities in centrifugally balanced ac cretion discs to the formation of gaseous clumps and stellar companions wh ich will influence the future evolution of massive protostars in the Hertz sprung–Russell diagram. We perform molecular line emission plus dust con tinuum radiative transfer calculations and compute synthetic images of dis c structures modelled by the gravito-radiation-hydrodynamics simulation of a forming stars\, in order to investigate the Atacama Large Millimeter/su bmillimeter Array (ALMA) observability of circumstellar gaseous clumps and forming multiple systems. We show that substructures are observable regar dless of their viewing geometry or can be inferred in the case of an edge- viewed disc. The observation probability of the clumps increases with the gradually increasing efficiency of gravitational instability at work as th e disc evolves. Our results motivate further observational campaigns devot ed to massive accretion discs as around the protostars S255IR-NIRS3 and NG C 6334I-MM1\, whose recent outbursts are a probable signature of disc frag mentation and accretion variability.\n\nhttps://iaus379.aip.de/event/1/con tributions/35/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://iaus379.aip.de/event/1/contributions/35/ END:VEVENT BEGIN:VEVENT SUMMARY:Global simulations of magnetised self-gravitating protoplanetary d isks DTSTART;VALUE=DATE-TIME:20200514T135500Z DTEND;VALUE=DATE-TIME:20200514T141500Z DTSTAMP;VALUE=DATE-TIME:20241101T160712Z UID:indico-contribution-4-17@meetings.aip.de DESCRIPTION:Speakers: Lucio Mayer (University of Zurich)\nIn the early st ages of a protoplanetary disk\, when its mass is a significant fraction of its star's\, turbulence generated by gravitational instability (GI) shoul d feature significantly in the disk's evolution. At the same time\, the di sk may be sufficiently ionised for magnetic fields to play some role in th e dynamics.\nThough usually neglected\, the impact of magnetism on the GI may be critical\, with consequences for several processes: the efficiency of accretion\, spiral structure formation\, fragmentation\, and the dynami cs of solids. In this paper\, \nwe report on the first global three-dimens ional magnetohydrodynamical simulations of a self-gravitating protoplaneta ry using the meshless finite mass (MFM)\nLagrangian technique.\nWe confir m that GI spiral waves trigger a dynamo that amplifies\nan initial magneti c field to nearly thermal amplitudes (plasma $\\beta \n\nhttps://iaus379.a ip.de/event/1/contributions/17/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://iaus379.aip.de/event/1/contributions/17/ END:VEVENT BEGIN:VEVENT SUMMARY:3D global simulations of the Vertical Shear instability DTSTART;VALUE=DATE-TIME:20200514T133000Z DTEND;VALUE=DATE-TIME:20200514T135000Z DTSTAMP;VALUE=DATE-TIME:20241101T160712Z UID:indico-contribution-4-22@meetings.aip.de DESCRIPTION:Speakers: Marcelo Fernando Barraza Alfaro (Max Planck Institut e for Astronomy\, Heidelberg)\nTurbulence is a key ingredient in the disk evolution and planet formation. However\, the origin of the low level of t urbulence recently observed in protoplanetary disks is not yet well unders tood.\nThe Vertical Shear Instability (VSI) is a candidate to be responsib le for the hydrodynamic turbulence in the outer regions of the disk.\nVia 3D global hydrodynamical simulations\, we study the evolution of the VSI i n an isothermal disk\, with and without an embedded planet. \nWe post-proc ess the outputs of the simulations to study the observability of the VSI. We produce synthetic observations of radiative transfer calculations of th e gas line emission. Further\, we investigate if kinematic signatures of h ydrodynamical turbulence are present in our predictions\, and if they are observable in the near future with ALMA.\nIn this talk\, I will present pr eliminary results on this project.\n\nhttps://iaus379.aip.de/event/1/contr ibutions/22/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://iaus379.aip.de/event/1/contributions/22/ END:VEVENT END:VCALENDAR