Spiral Structure in Galactic Disk
江草 芙実 (天文学教育研究センター)
In the local universe, more than half of galaxies are categorized as a disk galaxy, which often exhibit a spiral structure. Meanwhile, the fraction of disk (and spiral) galaxies is lower in the distant universe. It it thus likely that the fraction has increased as the universe evolves. However, how disk galaxies and their spiral structure have evolved and reached to the current status is not fully understood yet.
Theoretical models on spiral structure can be divided into two in terms of its lifetime: long-lived (density wave) or short-lived (swing amplification, tidal arms). In this talk, I will present how these models are compared to observational results on nearby galaxies.
Observational studies on spiral structures in distant galaxies are still limited. I will briefly review the current status and future prospects of researches on the evolution of spiral galaxies.
Superluminous supernovae and their origin
守屋 尭 (国立天文台)
Superluminous supernovae are a newly-recognized class of core-collapse supernovae that often become more than 10 times brighter than standard core-collapse supernovae. Among them, the energy source and progenitors of hydrogen-poor (Type Ic) superluminous supernovae are not well understood. It is likely that there is some sort of central energy source powering hydrogen-poor superluminous supernovae. After introducing the observational properties of hydrogen-poor superluminous supernovae, I will discuss their possible central power sources. Although their main power source is likely at the center, I will argue that several lines of evidence indicates the existence of dense massive circumstellar media around hydrogen-poor superluminous supernovae. I will also discuss the possible origin of such dense circumstellar media.
Connecting the dots: disk formation around low-mass stars to Solar System formation
Daniel Harsono (Leiden大学)
Stars and planet-forming disks form out of cold and dense clouds. One of the major questions in astrochemistry is whether or not the disk inherits the material of the protostellar envelope. Models of the young solar nebula, the disk that formed the Solar System, suggest that the chemical composition has been reset on the way to the disk. Some of these evidences are provided by the meteoritic studies. However, it has been only recently that it is possible to study the early stages of star formation in the spatial detail that matches the young solar nebula. I will present the on-going projects to understand the disk formation process and its implications on the early stages of planet formation.
hongo-astrotalks (at-sign) astron.s.u-tokyo.ac.jp