New Physics of dust and surface astrochemistry

Speaker: Dr. Thiem Hoang (KASI)

Date: 2019/10/08, Tuesday, 5 pm

Room: Science hall B102

Language: English

Abstract:

Dust is ubiquitous in the Universe and plays an important role in modern astrophysics. Dust is the building blocks of stars and planets and is the home where water ice and complex organic molecules, including biogenic molecules-building blocks of life, are formed and released into the gas. Dust grains absorb starlight in optical and ultraviolet wavelengths and re-emit radiation at infrared wavelengths, which is a powerful tool for astronomers to study the Universe. The alignment of dust grains results in the polarization of starlight and infrared emission from themselves, which is a popular technique to map cosmic magnetic fields. In this talk, I will present new physics of interstellar dust and surface astrochemistry. First, I will introduce a new mechanism of dust destruction based on centrifugal stress within extremely fast rotating grains spun-up by radiative torques, which is termed Radiative Torque Disruption (RATD) mechanism. I will show that the rotational disruption of dust grains into numerous small fragments can successfully explain longstanding puzzles in dust astrophysics, from Type Ia Supernovae, Massive young star clusters, to interplanetary dust in our solar system. Second, I will introduce new surface chemistry in space by presenting two new mechanisms to desorb water ice and complex organic molecules (COMs) from the icy grain mantle in star-forming regions, including rotational desorption and ro-thermal desorption. Finally, I will discuss the implications of newly discovered physics in the time-domain astronomy era using supernovae and gamma-ray bursts to probe early universe.