Latest talks

List of all the talks in the archive, sorted by date.

Tuesday September 12, 2017
Dr. Monika Lendl
Austrian Academy of Sciences, Space Research Institute


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.

Thursday August 24, 2017
Dr. Sébastien Comerón
University of Oulu, Finland


The reports of thick discs' death are greatly exaggerated: Thick discs are NOT artefacts caused by diffuse scattered light

Recent studies have made the community aware of the importance of accounting for scattered light when examining low surface brightness galaxy features such as thick discs. In past studies on thick discs of edge-on galaxies the point spread function (PSF) effects were not taken into account or were modelled with a Gaussian kernel.

We have re-examined results on photometric decompositions of discs in the Spitzer Survey of Stellar Structure of Galaxies (S4G) using a revised PSF model that accounts for extended wings out to more than 2.5 arcminutes. We study 141 edge-on galaxies, so we more than double the samples examined in past studies. This is the largest sample of extragalactic thick discs studied so far.

The main difference between our current fits and those presented in the past is that now the scattered light from the thin disc dominates the surface brightness at levels below 26 mag arcsec-2. This change, however, does not affect drastically any of our previously presented results: 

- Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 
- Thick discs have masses comparable to those of thin discs in low-mass galaxies (with circular velocities v_c<120 km s-2) whereas they are typically less massive than the thin discs in high-mass galaxies.
- Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir.
- Approximately sixty per cent of the up-bending breaks in face-on galaxies are caused by the superposition of a thin and a thick disc where the scale-length of the latter is the largest.

Friday July 14, 2017
Prof. David Nidever


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).

Wednesday July 12, 2017
Dr. Carlos Hernández Monteagudo


The Javalambre Photometric Local Universe Survey (aka J-PLUS) has covered almost 500 square degrees since it started operations in November 2015. J-PLUS is conducted by the 80-cm diameter Javalambre Auxiliary Survey Telescope (JAST/T80), which, despite its modest size, has a relatively large Field of View (~2 square degrees). The camera attached to JAST/T80 counts with a system of five broad band filters (u_JAVA, g_SDSS, r_SDSS, i_SDSS, z_SDSS) plus seven narrow band filters (of width ranging from 10 to 20 nm). Four of these narrow band filters are centered upon Halpha, Hdelta, Ca Triplet, and OII 3727A (rest frame).  After a strategic redefinition of  filter depths, JAST/T80 should cover the Javalambre sky at a speed of 1500 square degrees per year. I will briefly describe the instrument and the survey specifications, together with some of the scientific projects under development, and their preliminary results. I will also describe the J-PLUS online data base in an attempt to encourage members and potential members of the collaboration to exploit these data.

Thursday June 29, 2017
Prof. Ellen Zweibel
Univ. Wisconsin-Madison


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.

Tuesday June 27, 2017
Dr. Alicia Lopez
Instituto de Astrofisica de Canarias


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.

Thursday June 22, 2017
Dr. Haifeng Wang
National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China


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.

Tuesday June 13, 2017
Dr. Licai Deng
National Astronomical Observatories, CAS (China)


 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.

Thursday June 1, 2017
Dr. Ignacio Mateos


En 1915 Albert Einstein publica su teoría general de la relatividad y con ella predice la existencia de las llamadas ondas gravitacionales. Cien años después, dos importantísimos hitos científicos relacionados con esta predicción tienen lugar. Primero, el anuncio de la detección directa de ondas gravitacionales confirma la teoría de Einstein, marcando el comienzo de la Astronomía Gravitacional. El segundo hecho clave ha sido el éxito de la misión espacial LISA Pathfinder, satélite que ha probado la tecnología necesaria para los futuros observatorios de ondas gravitacionales en el espacio. Los continuos avances científicos y tecnológicos de las últimas décadas han permitido abrir esta nueva ventana a un universo lleno de revolucionarios descubrimientos que esperan ya ser desvelados.

Thursday June 1, 2017
Dr. Paula Jofre
University of Cambridge


Galactic archaeology is the study of the structure, formation and evolution of our galaxy, the Milky Way. Today, this is mainly done via combining the ages and the dynamical and chemical properties of various stellar populations. Thanks to on-going and future stellar surveys completing Gaia, data of millions of stars is becoming available. How to exploit this multidimensional data efficiently, which effectively will give the new insights on how to constrain models of Galactic formation and evolution, is becoming one of the major modern challenges of the field.


Phylogenetics, a concept being widely-used in biology, is the reconstruction of evolutionary history by building trees that represent branching patterns and sequences. These trees represent shared history, and it is our contention that this approach can be employed in the analysis of Galactic history, where the shared environment in which stars form provide the basis for tree-building as a methodological tool.  In this talk I will discuss how evolutionary trees can be built with twin stars and how this gains new insights into the structure and evolution of the Milky Way. 

Upcoming talks

Featured talks