SHAO Astrophysics Colloquia
LAMOST Observations in the Kepler Field and Measurements of the Stellar Parameters
Speaker: Jianning Fu (Beijing Normal University)
Time: Thursday, 3:00pm, June 4th
Location: Lecture Hall, 3rd floor
Abstract: The NASA Kepler satellite has provided unprecedented high duty-cycle, high-precision light curves for a large number of stars by continuously monitoring a field of view in Cygnus-Lyra region, leading to great progress in both discovering exoplanets and characterizing planet-hosting stars by means of asteroseismic methods. Although the asteroseismic survey allows the investigation of stars covering the whole H-R diagram, the low precision of effective temperatures and surface gravities in the KIC10 catalogue and the lack of information on chemical composition, metallicity and rotation rate prevent asteroseismic modelling, requiring spectroscopic observations for thousands of asteroseismic targets in the Kepler field in a homogeneous way. In 2010, we initiated the LAMOST-Kepler project which aimed at collecting low-resolution spectra for as many objects from the KIC10 catalogue as possible, with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), a 4-m telescope equipped with 4,000 optical fibers. The first round of observations has been completed in fall 2014, covering all the 14 sub-fields at least once, resulting in more than 100,000 low-resolution spectra. The stellar atmospheric parameters are then derived and the results have been confirmed to be consistent with those reported in the literature based on high-resolution spectroscopy. The data created by the LAMOST-Kepler project can not only be used for asteroseismic study for thousands of variable stars in the FoV of Kepler, but also provide a great potential for other research fields such as exoplanet-host stars, stellar activities and flares, and particular stars, etc., together with the time-series photometric data obtained by the Kepler mission.
Seminar talk
Title: The fundamental importance of understanding star cluster evolution
Speaker: Richard de Grijs (KIAA)
Time: Thursday,10:00am,June 4
Location: the middle conference room
Abstract: The"young star cluster group" att Peking University engages in a wide variety of research directions related to star cluster evolution. To study the evolution of dense, massive clusters, we use a combination of groud-and space-bases observations, combined with numerical simulations, of both resolved clusters in the Local Group and integrated observations of predominantly starburst events in the moredistant (still local) Universe. Following an overview of my group'smain achievements, I will focus on exciting new results on the veryrapid evolution of very young (< 20 Myrold) star cluster populations in circumnuclear rings in nearby starburst galaxies. Contrary toexpectations, we find that these populations are characterized by veryrapid evolution, which we suggest to have been induced bycluster-cluster and cluster molecular cloud collisions in the dense rings. Finally, I will highlight some of the latest results we haveobtained based on deep near-infrared observations of the Galactiglobular cluster 47 Tucanae, made with the 4m ESO/VISTA telescope inChile. We have uncovered clear evidence of a radially varying composition of multiple stellar populations within the cluster, aswell as signatures in the stellar mass functions of both mass segregation and the effects of tidal stripping.