Planet のバックアップ(No.119)

Planet Seminar 2023 †

Planet seminar is held at 15:00 every Thursday (Organizers: Yuichi Ito, Kenji Furuya)
Planet journal clup is held at 12:00 every Monday（Organizers: Yuji Matsumoto, Kazumasa Ohno, Chanoul Seo）

↑

Schedule & History †

FY2022 FY2021 FY2020 FY2019 FY2018 FY2017 FY2016 FY2015 FY2014

Date	Speaker	Title	Remarks	Person in charge
4/4 15:00-15:30	Shantanu Basu (University of Western Ontario)	The Magnetic Field versus Density relation in Molecular Clouds		Fumitaka Nakamura
4/17 13:00-13:30	Lizxandra Flores Rivera (University of Copenhagen)	Gas dynamics and forbidden emission lines from outflows, jets, and disk winds in protoplanetary disks		Akimasa Kataoka
4/17 13:30-14:00	Marcelo Barraza-Alfaro (MIT)	Predicting kinematical signatures of turbulence in ALMA high-resolution observations of CO rotational lines		Akimasa Kataoka
4/18 11:00-11:30	Raffaele Rani (國立台灣師範大學)	TBD		Kazunari Iwasaki
4/19 13:00-13:30	Quentin Changeat (STScI)	Exo-atmospheres in the era of JWST and Ariel		Yuichi Ito
4/19 13:30-14:00	Sushuang Ma (UCL)	An Exoplanet Cloud Simulation and Retrieval Package		Yuichi Ito
4/20 13:00-13:30	Taichi Uyama (NAOJ/Caltech)	Invitation to high-contrast hydrogen emission observations: detecting and characterizing accreting protoplanets in the context of planet formation		Yuka Fujii
4/20 13:30-14:00	Dipen Sahu (Physical Research Laboratory)	Density Structure of Centrally Condensed Prestellar Cores from Multi-scale Observations		Kenji Furuya
4/20 14:00-14:30	Chen-Hau Hsieh	The Evolution of Protostellar Outflow Cavities, Kinematics, and Angular Distribution of Momentum and Energy in Orion A: Evidence for Dynamical Cores		Fumitaka Nakamura
4/27 15:00-16:00	Yuhiko Aoyama (北京大学)	Type II planet-disk interaction in windy protoplanetary disks		Yuichi Ito
5/11 15:00-16:00	Sho Shibata (University of Zurich)	TBD		Yuichi Ito
5/18 15:00-16:00	Kazunari Iwasaki (NAOJ)	A Constraint on the Amount of Hydrogen from the CO Chemistry in Debris Disks	Paper introduction	Kenji Furuya
6/1 15:00-16:00	Kanako Seki (The University of Tokyo)	TBD	日本語	Yuichi Ito
6/22 15:00-16:00	Matías Gárate (MPIA)	The synergy between photoevaporation, dead zones, and substructures can explain transition disks

4/4 Shantanu Basu (University of Western Ontario), The Magnetic Field versus Density relation in Molecular Clouds: I present recent three-dimensional nonideal MHD simulations of the evolution of the magnetic field strength versus density in turbulent magnetically-dominated clouds. The results show a natural transition from a relatively flat regime into a power-law regime that is approximately described by magnetic flux freezing. We develop an analytic model that matches the main features of the simulations, and shows that there is a natural transition density from the flat to the power law regime, and that it depends on the ambient Alfven Mach number. I also review some recent DCF observations of magnetic fields in dense star-forming regions and show that an apparent B-rho exponent of 2/3 can be understood in the context of strong magnetic fields, unlike some common interpretations of that exponent.

4/19 Quentin Changeat (STScI), Exo-atmospheres in the era of JWST and Ariel: For the last decade, exoplanet atmospheres have been observed from space using transits, eclipses and phase-curves with the Hubble and Spitzer Space Telescopes. About a hundred exoplanets were characterised, providing crutial clues about their nature and formation. However, due to the narrow wavelength coverage and low signal-to-noise, inference of complex properties at the population level have remained challenging. Promising higher quality data for thousands of exoplanets, the NASA/ESA/CSA-JWST and the ESA-Ariel missions mark the new era of exo-atmospheric characterization. In this presentation, we will discuss some of the observational constraints that can be obtained by this next generation of space telescopes as well as some of the challenges associated with the analysis of this new data.

4/19 Sushuang Ma (UCL): An Exoplanet Cloud Simulation and Retrieval Package| The existence of cloud has been prevalent in the transit study of exoplanetary atmospheres. However, the cloud models for transit spectroscopy from the last decade are waiting for optimisation for the data from the next-generation telescopes. Here we present YunMa, a cloud simulation and retrieval package for retrieval study of cloudy atmospheres of exoplanets in transit spectroscopy. It is integrated into TauREx retrieval platform and has a flexible API for taking cloud or haze models coded in Python. The current YunMa has an inbuilt Ackerman & Marley cloud microphysics model. We simulate the vertical cloud particle size distribution from cloud microphysics and further the cloud contribution in the radiative transfer. YunMa integrated in Taurex is capable of retrieving the cloud microphysics parameters and showed huge improvement in the retrieval performance compared with the grey cloud model which is commonly used in the last decade. YunMa is applied in the population study of different tiers in the Ariel Dry-Run to follow up the observation tier selection of Ariel targets to provide a better consideration of cloud impact on the selection strategy.

4/27 Yuhiko Aoyama (北京大学): Type II planet-disk interaction in windy protoplanetary disks| Recent studies have established magnetized disk winds as the primary mechanism driving accretion and evolution in protoplanetary disks, which can co-exist with turbulence from the magneto-rotational instability (MRI) in the outer disk. We conduct 3D global non-ideal magnetohydrodynamic (MHD) simulations of type-II planet-disk interaction that properly resolves the MRI turbulence and accommodates the MHD disk wind. We found that the planet triggers the poloidal magnetic flux concentration around its orbit, likely associated with spiral density shocks. The concentrated magnetic flux strongly enhances angular momentum removal in the gap region and alters the torque balance, making the planet-induced gap shape more similar to an inviscid disk, while being much deeper. The gap region is characterized by a fast trans-sonic accretion flow that is asymmetric in azimuth about the planet and lacks the horseshoe turns. The formation of a magnetized circumplanetary disk will also be discussed.

6/22 Matías Gárate (MPIA): The synergy between photoevaporation, dead zones, and substructures can explain transition disks| There are many physical processes that are believed to shape the evolution of protoplanetary disks. Among them we can count the viscous spreading caused by the angular momentum redistribution, the dead zones in the inner disk where the turbulence is so low that stalls gas accretion, inside-outphotoevarative dispersal which is driven by the X-ray and UV radiation from the central star, and finally local substructures that can trap large amounts of dust during the early stages of disk evolution. All of these processes have been studied separately and can explain specific aspects of disk evolution, however it is not yet clear how they interact with each other when consider simultaneously. With this talk I show how the synergy between these ingredients can explain the puzzling properties of transition disks. In a hybrid model we find that early substructures take care of retaining the large amounts of dust that lead to the bright emission in the millimeter continuum seen in transition disks. The photoevaporative dispersal takes care of expanding a cavity to larger sizes, dragging all the accumulated material further and further from the star. And finally, dead zones allow to decouple the inner and outer outer regions during the dispersal process, which results in a long lived inner disk capable of sustaining the high accretion rates seen in these objects.