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國立清華大學天文研究所 NTHU Institute of Astronomy
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近期演講
Title: The Challenges and Joy of Doing Astronomy
 
Speaker: Professor Kong, Albert 江國興 (NTHU)
 
Time: 15:30pm 29nd Sep. 2017 (Friday)
 
Vanue: R521, IoA, 2nd General Building 綜二館R521
 
Abstract:
From solar eclipses, compact objects, to gravitational waves, I will share my experience of being an observational astronomer and show you how one can adopt new techniques in a rapidly changing world of astronomy.
 

Title: Cosmological simulation with Dust Formation and Destruction with ISM physics

Speaker: Dr. Aoyama, Shohei 青山尚平 (Academia Sinica Institute of Astronomy and Astrophysics)

Time: 3:30pm 22nd Sep. 2017 (Friday)

Vanue: R521, IoA, 2nd General Building 綜二館R521

Abstract:

Dust is an essential component in understanding star formation properties of galaxies both observationally and theoretically. When we consider the absorption of UV light by dust, the dust abundance and the grain size distribution are both important. Dust is formed and destroyed in multiple processes, which depend on the local metallicity, density and temperature. We implement these processes of dust into hydrodynamic simulation code GADGET3-Osaka taking into account of the evolution of dust size distribution. In order to realize it, we include dust formation end destruction processes in ISM, which are not only generation and destruction by supernovae but also accretion, coagulation and shattering. We obtained the time evolution of the abundance Ωdust(z), the mass function and the relation between dust-to-gas mass ratio to metallicity of each galaxy and radial profiles of dust grains. They agree with the corresponding observations.

Time: 2pm, Monday, August 14
 
Venue: R521, IoA, 2nd General Building
 
Speaker: Prof. Alex Lazarian (University of Wisconsin-Madison) 
 
Title: New way to study interstellar magnetic fields: velocity gradients

Abstract: 
 I shall discuss two new techniques of magnetic field tracing using spectral line data. The techniques employ the gradients of velocity in order to trace magnetic fields in the diffuse interstellar media as well as to trace regions of star formation associated with the gravitational collapse. The differences between these techniques is that they use different observationally available measures, i.e. the first one uses the velocity centroids and the other uses velocity channel maps. I shall provide the theoretical foundations of the techniques that are based on our modern understanding of MHD turbulence, the numerical testing of the techniques as well as the comparison of the directions obtained with the velocity gradients using GALFA HI data and those of magnetic field as traced by Planck as well as 13CO data and far infrared polarimetry with BLASTPOL.