Time：2024/03/29 (Fri.) 12:10-13:10
Place：4F Lecture Hall, Cosmology Hall, NTU

Title：Type Ia Supernova Progenitors and Surviving Companions within the Symbiotic Channel
Speaker：Hsin-Pei Chen (NTHU)
Abstract：
The symbiotic channel of Type Ia supernovae progenitors is crucial for explaining the observed circumstellar material in some Type Ia supernovae. While extensive numerical and observational efforts have been dedicated to exploring the progenitor system, limited emphasis has been placed on studying the surviving companions arising from the symbiotic channel. In this paper, we present a comprehensive numerical study of the symbiotic systems as potential Type Ia supernova progenitors. We conduct 1260 binary stellar evolution simulations using MESA, over a wide range of parameters, incorporating the optically thick wind model developed by Hachisu et al. In addition, we perform two-dimensional supernova simulations to explore the interaction between the supernova and the companion star, as well as to predict the post-impact evolution of these surviving companions. We classify four types of progenitor systems based on the evolutionary stage of the companion at the onset of the explosion: red giant companions, subgiant companions with prior helium flash events, and asymptotic giant branch companions, with or without the thermal pulsing phase. Our hydrodynamics simulations indicate that, regardless of the companion type, the envelope will be near-completely destroyed during the supernova impact. This leaves behind a faint blue dwarf star with either a helium or carbon core. However, if a small portion of the envelope (>~0.3%) falls back onto the core of the surviving companion, the overall post-supernova evolution may remain similar to its pre-explosion state, albeit slightly fainter, making observation a challenging endeavor.

Title：Finding Mysterious Planet 9 in AKARI Image
Speaker：Yu-An Chen (NTHU)
Abstract：
In recent years, several giant asteroids with similar orbital parameters have been observed. Like Sedna, GB32, CR105 etc, they are having similar inclinations and arguments of perihelion and they are all distant Kuiper Belt Objects(KBOs). To explain this phenomenon, simulation results suggest there exists a massive object beyond the orbit of Neptune, which is called Planet 9. With the gravitational perturbation from Planet 9, many KBOs are gathering in 3-dimensional space.
In this work, we try to find the grey body radiation of  Planet 9 in the space telescope AKARI’s archive data by identifying moving objects between different scans of the telescope. 

*registration will be closed at 03/27(Wed.)12:00 noon.