Date: Mon 29-August-2011
Speaker: Dr. Yu Gao (Purple Mountain Observatory, Chinese Academy of Sciences)
Title: "The Global Star Formation Laws in Galaxies"
Abstract: The high-dipole moment molecules such as HCN and CS trace much denser molecular gas than that of CO (the total molecular gas mass tracer). HCN strongly and linearly correlates with the far-infrared (FIR) emission for essential all star-forming systems near and far. CS observations in galaxies further demonstrate similarly tight correlations. The locally resolved FIR-HCN correlation or a local star formation law in terms of dense molecular gas across the inner disks in nearby spirals is also being established. Such tight linear FIR - dense molecular gas correlation suggests that the star formation rate (SFR) depends essentially linearly upon the mass of dense molecular gas and the tiny dense cores inside the giant molecular clouds might be the basic units of massive star formation in galaxies. This is drastically different from the traditionally established Kennicutt-Schmidt star formation laws that relates the total gas to SFR in galaxies which have no unique slopes in the correlations.
Date: Mon 17-October-2011
Speaker: Catrina Hamilton-Drager (Dickinson College)
Title: KH 15D: New Insights into the Nature of its Protoplanetary Disk
In the standard model of terrestrial planet formation, the first step in the process is for interstellar dust to coagulate within a protoplanetary disk surrounding a young star, forming large grains that settle toward the disk plane. Here I will present a review of the pre-main sequence T Tauri binary system, KH 15D. The fortuitous geometry of this system has allowed us to learn more about the physical state of its circumbinary disk. With a total mass near one solar mass and an age of ~ 3 Myr, KH 15D may be particularly relevant to understanding the first stage of planet formation and at least one class of transition disk.
