Recent Talks

Planetary transits have proven to be one of the most efficient means of finding planets outside the Solar system, counting over 2500 exoplanet discoveries. These transiting planets are paramount for the study of exoplanet atmospheres as the stellar light is filtered through the planetary atmosphere during transit and planetary absorption signatures become imprinted on the stellar spectrum. Observations of hot-Jupiter transmission spectra have become increasingly numerous and reliable throughout recent years, allowing detailed constrains on the planet's physical and chemical atmospheric properties, interactions between planet and host star, and planet formation history. While early work relied largely on space-based facilities, ground-based techniques have seen major advances recently and have become instrumental in performing an extensive and comparative study of exoplanet atmospheres. I will review the current state of knowledge, summarize recent results and discuss future prospects of exoplanet characterization, with a focus on the potential of ground-based facilities. In particular, I will present recent and new results by our team on the transmission spectra of hot Jupiters.

How galaxies form and evolve remains one of the cornerstone questions in our understanding of the universe on grand scales.  While much progress has been made by studying galaxy populations out to high redshifts, there is also much to be learned from near-field cosmology ? that is, investigating nearby galaxies in detail using observations of resolved stars.  I will highlight some recent results from several projects that are providing new insights into the structure and formation history of the Milky Way and the Magellanic Clouds.  First, I will discuss how I am mapping the stellar halos of the Milky Way and the Magellanic Clouds and thereby uncovering clues to their hierarchical buildup.  Second, I will summarize results from the APOGEE survey that, in combination with high-resolution simulations, are revealing the chemical structure, evolution and dynamical history of the Milky Way disk.  I will end with a brief summary of my recent work with the NOAO Data Lab to create an all-sky catalog of NOAO archive images (the NOAO Source Catalog or NSC).

Star formation and supermassive black hole growth in galaxies appear to be self limiting. The mechanisms for self regulation are known as /feedback/. Cosmic rays, the relativistic particle component in interstellar and intergalactic plasma, are among the agents of feedback. Because cosmic rays are virtually collisionless in the plasma environments of interest, their interaction with the ambient medium is primarily mediated by large scale magnetic fields and kinetic scale plasma waves. Because kinetic scales are much smaller than global scales, this interaction is most conveniently described by fluid models. In this paper I discuss the kinetic theory and the classical theory of cosmic ray hydrodynamics (CCRH) which follows from assuming cosmic rays interact only with self excited waves. I generalize CCRH to generalized cosmic ray hydrodynamics (GCRH), which accommodates interactions with extrinsic turbulence, present examples of cosmic ray feedback in galaxies and galaxy clusters, and assess where progress is needed.

The improvement on the Imaging Air Cherenkov Technique led to the discovery of a new class of compact binaries: the gamma-ray binaries. This small class consist  of only five members, all of them composed by a massive star and a compact object. The nature of the compact object is unknown for all of them but PSR B1259-63, which contains a pulsar. It is crucial to study and monitor these systems not only to understand their behavior, the scenario accounting for the gamma-ray emission and their nature but also to comprehend why we have not detected more sources of this exclusive family. In this presentation, I will review the state-of-the-art of this field and I will present the observations performed with the MAGIC telescopes in order to unveil the nature of gamma-ray binaries.

Based on radial profiles, disk can be divided into three categories:Type I, classical single exponential (10%); Type II, down-bending joint exponential (60%); Type III, up-bending joint exponential (30%). Milky Way is the benchmark for the research of the disk Galaxy formation and evolution! And the outer disks of galaxies present a unique laboratory for studying the process of disk formation and it can provide us with a direct view of disk assembly in progress. I will introduce my recent work about the milky way outer disk. And some highlights about our group works with LAMOST data will also be mentioned.

 China joined SONG in 2009, by contributing a full SONG node. The site is located on the north-eastern part of Qinghai-Tibet 
plateau. In order to realize the full capability of the SONG network, and more importantly for Chinese astronomical community 
to gain experience of running oversea observing facilities, we proposed to our collaborators to add a wide-field photometry 
system on each SONG node based on the same site plan. The sub-net is named 50cm Binocular Network (50BiN), which provides 
time-series photometry of simultaneous two-bands (any two of UBVRI-ugriz), and ideally full duty cycle in networked mode 
(if the full SONG would be built). The proto-type 50BiN node has been in operation on Chinese site (Delingha) for 3 years. 
An overview of the grand science plan, configuration of the network and instruments, as well as some science cases will be 
presented in this talk. A brief introduction to the status of ground-based Chinese observing facilities will also be covered.