August 21 Mon 14:30-15:30 ALMA-J seminar Zoom / ALMA building #102 (hybrid)
August 23 Wed 14:30-15:30 ALMA-J seminar Zoom
詳細は下記からご覧ください。
=============== August 21 Mon===============
Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Sporadic
Date and time: August 21, 2023 (Mon), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Martin Bureau
Affiliation: University of Oxford
Title: WISDOM: Molecular cloud properties and star-formation quenching
Abstract: Molecular gas is the fuel for star formation in galaxies. Using observations from the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM), that spatially resolve (1-30 pc) individual molecular clouds across the Hubble sequence, I will reveal a clear dependence of the nature of the molecular interstellar medium of galaxies on Hubble type, and present a simple diagnostic of cloud formation. In particular, I will highlight the shortcomings of the usual virial approach to clouds as self-gravitating objects, and stress the importance of the external galactic potential and in-plane shear to regulate the dynamical states of clouds. I also introduce a simple but powerful cloud-cloud collision formalism that accounts for the cloud properties of several nearby as well as high-redshift systems. Finally, I note the peculiar properties of clouds within the bars of spiral galaxies, and I discuss the impact of these different mechanisms on the star formation efficiency of clouds and thus the quenching of star formation, particularly in galaxy nuclei and spheroids (morphological quenching).
Facilitator: Bunyo Hatsukade, Kouichiro Nakanishi
=============== August 23 Wed===============
Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: August 23, 2023 (Wed), 14:30-15:30
Place: Zoom
Speaker: Takashi Shimonishi
Affiliation: Niigata University
Title: The Role of Metallicity in the Chemical Evolution of Star-forming Regions
Abstract:
Understanding the chemistry of the interstellar medium at low metallicity is crucial to unveil physical and chemical processes in the past Galactic environment or those in high-redshift galaxies, where the metallicity was significantly lower compared to the present-day solar neighborhood. In the last decade, there has been a great progress in astrochemical studies of interstellar molecules in low-metallicity star-forming regions. Nearby low-metallicity laboratories, such as the Large and Small Magellanic Clouds, Local Group dwarf galaxies, and the outskirts of our Galaxy, play an important role in such studies. Single-dish radio observations have detected various dense gas tracers in those regions, which revealed the molecular-cloud-scale (<1-10 pc) chemistry at low metallicity. With ALMA, emission from dense and high-temperature molecular gas associated with embedded protostars (i.e., hot molecular cores) are detected in the LMC, SMC, and outer Galaxy, which revealed the chemical complexity of star-forming cores (<0.1 pc) at low metallicity. Besides gas-phase species, infrared observations have revealed chemical compositions of ices around deeply embedded protostars in the LMC and SMC. Do molecular abundances simply scale with the metallicity? If not, which processes govern the chemistry in the low-metallicity interstellar medium? In this presentation, I will discuss the role of metallicity in the chemical evolution of star-forming regions based on recent observations of interstellar molecules in low-metallicity environments.
Facilitator: Bunyo Hatsukade, Kouichiro Nakanishi