BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:A massive planet disruption as the source of dust in TW Hydra prot oplanetary disc DTSTART;VALUE=DATE-TIME:20200513T084500Z DTEND;VALUE=DATE-TIME:20200513T090500Z DTSTAMP;VALUE=DATE-TIME:20240704T115533Z UID:indico-contribution-8-58@meetings.aip.de DESCRIPTION:Speakers: Sergei Nayakshin (University of Leicester)\nThe prot ostar TW Hydra features the best studied and one of the most unusual proto planetary discs. Its dust disc has a cliff-like rollover at 52 AU which co incides with a suspected sub-Neptune mass planet recently detected as an a zimuthally elongated AU-scale excess in ALMA 1.3 mm continuum (Tsukagoshi +19). Here we build detailed models of dust growth\, dynamics and syntheti c disc emission to investigate the origin of TW Hydra's peculiarities.\n\n \nWe show that the standard scenario in which the dust in TW Hydra disc is primordial accounts neither for the dust morphology nor the excess emissi on. We propose an alternative model in which the primordial dust is long c onsumed by the star or locked in planets\; the dust currently observed in the system is ejected by the suspected ALMA planet. We show that in this m odel the mm-sized dust particles are blown inside the planetary orbit\, na turally explaining the dust disc morphology and its relation to the 1.3 mm excess. Further\, dust lost by the planet performs a characteristic U-tur n relative to the planet producing an azimuthally elongated emission featu re similar to the one observed by ALMA. Finally\, the disruption scenario provides an attractive explanation for why one of the oldest protoplanetar y discs happens to be tens times more massive in terms of dust than most d iscs a fraction of TW Hydra's age.\n\n\nWe consider two scenarios for the nature of the dust-loosing planet. In the first\, a dusty pre-collapse gas envelope of a massive core growing in the Core Accretion framework is dis rupted\, e.g.\, as a result of a catastrophic encounter. In the second\, a massive dusty gas giant planet formed in the Gravitational Instability sc enario is disrupted by the energy release in its massive core. In the latt er case all of TW Hydra protoplanetary disc\, including its gaseous compon ent\, may originate in such a disruption\; the planet mass has to be no la rger than 2 Jupiter masses and it must be 5-10 times more abundant in meta ls than the Sun.\n\nIf these ideas are correct then future observations of TW Hydra\, and potentially other discs\, will allow us to study planet fo rmation in an entirely new way -- by analysing the flows of dust and gas r ecently belonging to giant planets. Reverse engineering of mass loss from the planets may inform us about their density structure and elemental comp osition before the disruption.\n\nhttps://meetings.aip.de/event/1/contribu tions/58/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://meetings.aip.de/event/1/contributions/58/ END:VEVENT BEGIN:VEVENT SUMMARY:Dust Settling Instability in Protoplanetary Disks DTSTART;VALUE=DATE-TIME:20200514T122000Z DTEND;VALUE=DATE-TIME:20200514T124000Z DTSTAMP;VALUE=DATE-TIME:20240704T115533Z UID:indico-contribution-8-47@meetings.aip.de DESCRIPTION:Speakers: Leonardo Krapp ()\nThe streaming instability has bee n identified as a promising mechanism to concentrate solids and promote pl anetesimal formation in the midplane of disks. It has been demonstrated i n Squire & Hopkins (2018) that a related settling (and streaming) instabil ity (here SSI) occurs as particles sediment towards the midplane. However \, the ability of the SSI to concentrate solids and generate turbulence i s yet to be addressed. To shed light on this aspect\, we present a system atic study of the saturated state of the SSI by performing a series of num erical simulations with the multi-fluid version of the FARGO3D code. We fu rthermore have extended the existing linear analysis to more realistic sce narios including particle size distributions and background disk turbulenc e. Our findings suggest that particle clumping is too weak to trigger pla netesimal formation during the settling of particles\, but the SSI could g enerate weak levels of turbulence in otherwise nearly laminar regimes.\n\n https://meetings.aip.de/event/1/contributions/47/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://meetings.aip.de/event/1/contributions/47/ END:VEVENT BEGIN:VEVENT SUMMARY:Pebble accretion in turbulent discs DTSTART;VALUE=DATE-TIME:20200514T115500Z DTEND;VALUE=DATE-TIME:20200514T121500Z DTSTAMP;VALUE=DATE-TIME:20240704T115533Z UID:indico-contribution-8-45@meetings.aip.de DESCRIPTION:Speakers: Giovanni Picogna (Universitäts-Sternwarte München\ , LMU)\nPlanets are born in the mid-plane of accretion discs around young protostars. This process takes place most likely in weakly ionised regions \, where the evolution of the environment is driven by internal turbulence and the gas flow is not laminar but has stochastic components. Turbulence can be generated purely hydrodynamically via different instabilities\, li ke the vertical shear instability (VSI). A fast pathway to the formation o f giant planetary cores has been recently identified in pebble accretion\, though a realistic investigation of this process in a turbulent environme nt was necessary. We tested the solid accretion of a large range of dust s izes on to different planetary core masses in a VSI turbulent global 3D di sc and compared it with a laminar disc. Furthermore\, we tested the influe nce of a realistic equation of state and radiative cooling on the efficien cy of pebble accretion. We found that turbulence decreases slightly the so lid accretion efficiency with respect to analytical calculations of lamina r discs\, having a ~2% efficiency of pebble-like particles for a 5 Earth-m ass planet at 5 au. The introduction of radiative transfer can affect this result significantly by changing the aspect ratio of the disc\, thus the pebble isolation mass.\n\nhttps://meetings.aip.de/event/1/contributions/45 / LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://meetings.aip.de/event/1/contributions/45/ END:VEVENT BEGIN:VEVENT SUMMARY:The impact of ice mantles on dust evolution in dynamically evolvin g protostellar discs DTSTART;VALUE=DATE-TIME:20200514T113000Z DTEND;VALUE=DATE-TIME:20200514T115000Z DTSTAMP;VALUE=DATE-TIME:20240704T115533Z UID:indico-contribution-8-26@meetings.aip.de DESCRIPTION:Speakers: Tamara Molyarova (Institute of Astronomy\, Russian A cademy of Sciences)\nThe snowlines of various volatiles are often associat ed with dust evolution in protoplanetary discs and may be identified in ob servations due to their impact on dust properties. In the vicinity of snow lines icy mantles of dust grains sublimate\, which can lead to a different regime of dust growth. Dynamical effects of icy grains crossing snowlines may be reflected in the distribution of volatiles in the gas phase.\nIn t his work\, we present the FEOSAD model of protostellar disc with dust evol ution\, updated to include evolution of icy mantles. The chemical part of the model accounts for time-dependent absorption and desorption of main di sc volatiles (H$_2$O\, CO$_2$\, CH$_4$\, and CO) on two evolving populatio ns of dust grains: small and grown dust. This 2D hydrodynamic code allows to consider the feedback of ice mantles on dust evolution through variable fragmentation velocity. \nWe discuss if the dynamical effects when calcul ating the snowline positions are important for dust growth. We analyse the impact of ice mantles on dust evolution in protostellar discs and discuss the role of ices in the process of planet formation.\n\nhttps://meetings. aip.de/event/1/contributions/26/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://meetings.aip.de/event/1/contributions/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Planet Formation By Chondrule Accretion DTSTART;VALUE=DATE-TIME:20200513T093500Z DTEND;VALUE=DATE-TIME:20200513T095500Z DTSTAMP;VALUE=DATE-TIME:20240704T115533Z UID:indico-contribution-8-46@meetings.aip.de DESCRIPTION:Speakers: Åke Nordlund (Niels Bohr Institute\, Copenhagen)\nR ecently performed nested-grid\, high-resolution hydrodynamic and radiation -hydrodynamics simulations of gas and particle dynamics in the vicinity of Mars- to Earth-mass planetary embryos (Popovas et al 2018MNRAS.479.5136P and 2019MNRAS.482L.107P) have provided quantitatively robust estimates of accretion rates for planet embryos formed inside a pressure trap. The simu lations extended from the resolved surfaces of the embryos to several vert ical disk scale heights\, with a vertical dynamic range exceeding 1e5. He ating due to the accretion of solids caused vigorous convective motions\, however even convection driven by a nominal accretion rate one Earth mass per Myr did not significantly alter the pebble accretion rate. Ray-trac ing radiative transfer showed that rocky planet embryos embedded in protop lanetary disks can retain hot and light atmospheres throughout much of the evolution of the disks.\n\nImportantly\, the results showed that particle s larger than the chondrules ubiquitously observed in meteorites are not required to explain the accretion of rocky planets such as Earth and Mars within the lifetime of the disk. Due to cancellation effects\, accretion rates of a given size particles are nearly independent of disk surface de nsity\, while proportional to the dust-to-gas ratio. As a result\, accura te growth times for specified particle sizes may be estimated. For 0.3-1 m m size particles\, and assuming a dust-to-gas ratio of 1:100\, the growth time from a small seed is ~1.5 million years for an Earth mass planet at 1 AU and ~1 million years for a Mars mass planet at 1.5 AU. \n\nThe magnitu de and robustness of the accretion rate estimates hinges on the assumption of the embryo residing in a pressure trap. A vertically projected dust to gas ratio of 1:100 is thus a lower limit\, with continued trapping of m m-size particles expected to accelerate accretion. This mechanism is the refore a prime candidate to explain rapid formation of rocky planets\, lea ving open only the question of by which mechanism the accretion is quenche d\, thus determining the final mass.\n\nI will discuss provocative scenari os where this question is resolved\, including implications for the format ion of gas dwarfs and gas giants.\n\nhttps://meetings.aip.de/event/1/contr ibutions/46/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://meetings.aip.de/event/1/contributions/46/ END:VEVENT BEGIN:VEVENT SUMMARY:Evolution and growth of dust grains in protoplanetary disks with m agnetically driven disk wind DTSTART;VALUE=DATE-TIME:20200513T091000Z DTEND;VALUE=DATE-TIME:20200513T093000Z DTSTAMP;VALUE=DATE-TIME:20240704T115533Z UID:indico-contribution-8-42@meetings.aip.de DESCRIPTION:Speakers: Tetsuo Taki (National Astronomical Observatory of Ja pan)\nMagnetically driven disk winds (MDWs) are one of the promising mecha nisms of dispersal processes of protoplanetary disks (Suzuki et al. 2010\, Bai 2013). When the MDWs play a key role\, the gaseous component of proto planetary disks evolves in a different manner from that of the classical v iscous evolution. As a result\, the subsequent planet formation is also af fected by the MDWs. In this work\, we investigate the effects of the MDWs on the radial drift of solid particles with a size of 0.1$\\mu$m - 1km. We propose that the MDWs is a possible solution to the ``radial drift barrie r'' of collisionally growing dust grains\, which is a severe obstacle to t he planet formation (e.g.\, Nakagawa et al.1986).\nIn order to study the e volution of dust grains in the disks\, we calculate the advection and coll isional growth of dust particles in evolving protoplanetary disks under th e 1+1 D (time + radial distance) approximation. We solve a coagulation equ ation of solid particles under a single-size approximation (Sato et al. 20 16) for various conditions of turbulent viscosity\, the mass loss by the M DW\, and the magnetic braking by the MDW.\nWe found that significant grain growth occurs in the inner region of the protoplanetary disks. The grown dust particles are larger than the km-sized bodies and they are no longer caught by the radial drift barrier. The mechanism of such successful dust growth is separated into two parts: (1) the increase of the equilibrium si ze of the dust particles caused by the convergent flow of the dust mass an d dispersal of the gas component\, (2) the unstable dust growth driven by the feedback loop between the size\, radial drift velocity\, and surface d ensity of the dust component. The disk evolution owing to the MDWs strongl y supports the former part of the growth mechanism. When the equilibrium s ize of the dust particles reaches the size that the Stokes number of the d ust particles exceeds unity\, the dust size evolution shift to the unstabl e mode (i.e.\, the latter part).\nBecause of the successful growth of dust particles\, the ring-like structure containing the planetesimal sized bod ies can be formed at the inner part of the protoplanetary disks. We will d iscuss the effects of such the ring-like structure on the subsequent plane tary system formation and the disk observations.\n\nhttps://meetings.aip.d e/event/1/contributions/42/ LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall URL:https://meetings.aip.de/event/1/contributions/42/ END:VEVENT END:VCALENDAR