SHAO Astrophysics Colloquia
The production of dust by evolved stars in the Magellanic Clouds
Speaker: Ciska Kemper (Academia Sinica, Institute of Astronomy and Astrophysics; ASIAA)
Time: Wednesday, 3:00pm, November 18th
Location: Lecture Hall, 3rd floor
Abstract: Within the context of the hugely successful SAGE-LMC and SAGE-SMC surveys, Spitzer photometry observations of the Large and Small Magellanic Clouds have revealed millions of infrared point sources in each galaxy. The brightest infrared sources are generally dust producing and mass-losing evolved stars, and several tens of thousands of such stars have been classified. After photometrically classifying these objects, the dust production by several kinds of evolved stars -- such as Asymptotic Giant Branch stars and Red Supergiants -- can be determined. SAGE-Spec is the spectroscopic follow-up to the SAGE-LMC survey, and it has obtained Spitzer-IRS 5-40 micron spectroscopy of about 200 sources in the LMC. Combined with archival data from other programs, observations at a total of ~1000 pointings have been obtained in the LMC, while ~250 IRS pointings were observed in the SMC. Of these, a few hundred pointings represent dust producing and mass-losing evolved stars, covering a range in colors, luminosities, and thus mass-loss rates. Red Supergiants and O-rich and C-rich AGB stars -- the main dust producers -- are well represented in the spectroscopic sample. In this talk I will review what we know about the mineralogy of dust producing evolved stars, and discuss their relative importance in the total dust budget.
SHAO-USTC Lecture
Title: 黑洞与中子星吸积的X射线观测
Speaker: Wenfei Yu(SHAO)
Time: Monday, 2:00pm, November 16th
Location: Room 1617
Seminar talk
Title: Dense gas in low metallicity systems
Speaker: Dr. Jonathan Braine (Observatoire de Bordeaux)
Time: Tuesday , 3:00pm,November 15th
Location:Lecture Hall, 3rd floor
Abstract: The rate of star formation is proportional to the mass of molecular gas over a broad range of objects...but not all. The mass of dense gas, more difficult to measure, appears to a better indicator of the star formation rate. The HCN(1-0) line luminosity is the standard, and possibly the best, tracer of the dense gas mass. However, while we expect the tight relationship between dense gas and star formation to hold regardless of metallicity, the HCN emission becomes very weak in low metallicity systems. I will present recent and still unpublished observations of dense gas observations in low metallicity local galaxies covering a variety of emission lines. And discuss the possible reasons for the weak HCN emission and how this could affect measurements of high redshift systems.
Group meetings and additional talks
Stellar Cluster and Galaxy Seminar group seminar
Location: 1617; Contact: Jian Fu<fujian@shao.ac.cn>
http://cluster.shao.ac.cn/wiki/index.php/Seminar_Plan
Blackhole accretion theory and High-energy astrophysics Seminar
Location: 1608; Contact: Qixiang Yang < qxyang@shao.ac.cn>
http://202.127.29.4/fyuan/journalclub.html