Seminars and Colloquia at ESO/Santiago

For ESO and ESO-related Conferences and Workshops in Europe and Chile please check the main Conferences and Workshops page.


Broadcast of the ESO talks is available upon request.  If anyone is interested, kindly contact us via email
at least 30 min prior  to the beginning of the talk.


September 2014

25.9.14 (Thursday)
12:00
"The TRAPPIST comet survey"
Cyrielle OPITOM (Institut d'Astrophysique de l'Université de Liège)
Abstract
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"The TRAPPIST comet survey"

Cyrielle OPITOM (Institut d'Astrophysique de l'Université de Liège)

Abstract

TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that has been installed in June 2010 at the ESO La Silla Observatory. Operated from Liège (Belgium) it is devoted to the detection and characterization of exoplanets and to the study of comets and other small bodies in the Solar System. We describe here the hardware and the goals of the project. 25 % of the time is dedicated to the study of small bodies of the Solar System and I will focus on this part of the project. Even though we also monitor faint comets, perform asteroids rotational lightcurves and observe stellar occultation by trans-Neptunian objects, the main goal of this program is the study of bright comets. We use narrow band cometary filters isolating the main emission bands visible in the optical spectrum of comets and zones of the dust reflected continuum. Thanks to the temporal coverage achievable with TRAPPIST, we perform long term monitoring of the activity and coma composition of bright comets. In some cases we can determine their nucleus rotation period and we can also react fast and observe a comet almost immediately after an outburst. Our measurements of gas and dust production rates allow assessing the activity of the comet prior to observing with bigger telescope (VLT, Keck or even space telescopes). I will present several results from these observations which are part of my PhD thesis work.

October 2014

3.10.14 (Friday)
12:00
"Mean velocity flows as dynamical signatures of spiral structure in the Milky Way"
Benoit FAMAEY (Observatoire Astronomique de Strasbourg)
Abstract
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"Mean velocity flows as dynamical signatures of spiral structure in the Milky Way"

Benoit FAMAEY (Observatoire Astronomique de Strasbourg)

Abstract

In an equilibrium axisymmetric galactic disc, the mean galactocentric radial and vertical velocities are expected to be zero everywhere. In recent years, various large spectroscopic surveys, including the RAVE survey, have however shown that stars of the Milky Way disc exhibit nonzero mean velocities outside of the Galactic plane in both the Galactocentric radial and vertical velocity components. While radial velocity structures are commonly assumed to be associated with nonaxisymmetric components of the potential such as spiral arms or bars, nonzero vertical velocity structures are usually rather attributed to excitations by external sources such as a passing satellite galaxy or a small dark matter substructure crossing the Galactic disc. Through solutions of linearized Jeans equations for a zero velocity-dispersion population, and through 3D test-particle simulations, I however show that the global stellar response to a spiral perturbation induces both a radial velocity flow and nonzero vertical motion, and that the resulting structure of the mean velocity field is qualitatively similar to what is observed across the Milky Way disc.

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