Latest talks

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

Tuesday September 19, 2017
Dr. Yi Zheng
KASI, South Korea


Tuesday September 19, 2017
Prof. Will Percival
University of Portsmouth, UK


Monday September 18, 2017
Dr. Sergio Pastor
IFIC, University of Valencia, Spain




Monday September 18, 2017
Dr. Martín Crocce
Institute for Space Science, Barcelona, Spain


Monday September 18, 2017
Dr. Diego Blas
CERN, Switzerland


Monday September 18, 2017
Prof. Yun Wang
California Institute of Technology, USA


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.

Upcoming talks

Featured talks