SHAO Astrophysics Colloquia

Title: Is the IMF Universal in Galaxies? A MaNGA View

Speaker: Shude Mao (毛淑德教授 Tsinghua/NAOC)

Time: 3 PM, January 5 (Thursday)

Location: Lecture Hall, 3rd floor

Abstract: I will provide a critical review about the variation of the IMF in galaxies from gravitational lensing, and more importantly, from dynamics using SDSS-IV MaNGA data.

Galaxy Seminar

Location: 1714

Time: 10:30, Jan.04 (Wednesday)

Title: New PARSEC database of alpha-enhanced stellar evolutionary tracks and isochrones

Speaker: 符晓婷 (意大利SISSA)

Contact: Jian Fu, Fangting Yuan, Chunyan Jiang, Zhaoyu Li, Ting Xiao

Abstract:

Precise studies on the Galactic bulge and multiple populations of globular cluster require stellar model with alpha enhancement and various helium contents. It is also important for extra- Galactic study to have  alpha enhanced population synthesis. For this purpose we expand PARSEC model from solar-scaled composition to alpha enhanced mixtures. The new model is calibrated with globular cluster 47Tuc (NGC104).  We then apply the calibration and alpha enhanced mixture based on the two 47Tuc populations ( [alpha/Fe] ∼0.4 and 0.2) to other metallicities. The new model  closes the gap between the observation and model prediction on the RGB bump. Besides the alpha enhanced metal mixture in 47Tuc, we also calculate evolutionary tracks based on metal mixtures from ATLAS9 APOGEE atmosphere model.

Group meetings 

Black hole Accretion and High-energy Astrophysics /Black Hole Feedback and Cosmic Ray Astrophysics Seminar

Location: 1608

Time: 14:00-16:00, Wednesday (Jan. 4th)

Speaker: Defu Bu

Title:Dust Transport in MRI Turbulent Disks: Ideal and Non-Ideal MHD With Ambipolar Diffusion

http://adsabs.harvard.edu/abs/2015ApJ...801...81Z
Speaker: Peiyao Xu

Title:A Molecular Disk around the Episodic Jets in KjPn 8

http://adsabs.harvard.edu/abs/1997ApJ...483L..57H

Galactic Dynamics Group Journal Club

Location：1608

Time：9:30-11:00,Jan. 05 (Thursday)

Speaker: Baile Li

Title:  Orbital classification in an N-body bar

Link: https://arxiv.org/abs/1609.02632 

Abstract: The dynamics and evolution of any galactic structure are strongly influenced by the properties of the orbits that constitute it. In this paper, the authors compare two orbit classification schemes, one by Laskar (NAFF) , and the other by Carpintero and Aguilar (CA), by applying both of them to orbits obtained by following individual particles in a numerical simulation of a barred galaxy. They find that, at least for our case and some provisos, the main frequencies calculated by the two methods are in good agreement: for

80% of the orbits the difference between the results of the two methods is less than 5% for all three main frequencies. However, it is difficult to evaluate the amount of regular or chaotic bar orbits in a given system. The fraction of regular orbits obtained by the NAFF method strongly depends on the critical frequency drift parameter, while in the CA method the number of fundamental frequencies strongly depends on the frequency difference parameter Lr and the maximum integer used for searching the linear independence of the fundamental frequencies. They also find that, for a given particle, in general the projection of its motion along the bar minor axis is more regular than the other two projections, while the projection along the intermediate axis is the least regular.