Title: Lithium problems: on the main sequence and the red giant branch

　　Speaker: Xiao-Ting Fu (SISSA, Italy)

　　Time: 2:30-3:30 pm, Dec.24rd

　　Place: Room 212, Astronomy Building, Xianlin Campus

　　Abstract: The abundance of Lithium constrains models of big bang nucleosynthesis, stellar structure and the age of stellar clusters. Lithium abundances therefore play a special role in our understanding of the universe. However, there are two major outstanding puzzles about stellar lithium abundances. Population II dwarfs are observed to possess lithium abundances in a plateau which is lower than the primordial value by a factor of three, and no stars are detected in the "forbidden zone". Where does the lithium go to? In red giant branch stars, lithium should be burnt because of their deep convective envelope, but about 1% of red giant stars exhibit glaring exceptions. Some of them even display lithium abundances even higher than the primordial value. These stars cannot be explained by standard stellar evolution models. Where does the lithium come from? I will talk about these two puzzles and possible solutions from both theoretical and observational perspectives.

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　　Title: The CMB effect on the submm observations for high-z galaxies.

　　Speaker: Zhi-Yu Zhang (University of Edinburgh / ESO)

　　Time: 3:30-4:30 pm, Dec.24rd

　　Place: Room 212, Astronomy Building, Xianlin Campus

　　Abstract: The cosmic microwave background (CMB) plays an important role in the radiative transfer of dust and gas emission, especially for the high redshift systems. As the CMB temperature increases with redshift, the CMB temperature can reach to the dust temperature or even exceed the intrinsic dust temperature at high redshifts. Two effects are essential but often be neglected for sub-mm observations: CMB heating on the cold dust, and the background subtraction in submm observations. Combining with these two effects and simple toy models, we discuss the influence to the submm measurement of fluxes and sizes of galaxies at high redshifts.

欢迎各位老师、同学参加！

　　                                        南京大学天文与空间科学学院