All future seminars

Number of entries: 2

22
February 2019

Asteroseismology of Red-Giant and Solar-Analogue stars in the golden age of space photometry and ground-based spectroscopy


Start: 12:15h
Speaker: Paul Beck (Instituto de Astrofisica de Canarias)
Place: Sala Alberto Lobo

Asteroseismology is a powerful tool to study structure and dynamics of the stellar interior as well as their evolution. Such analysis can be done for thousands of stars in differing evolutionary stages from data of unprecedented photometric quality, provided by the NASA Kepler space telescope. In particular,…
Start: 12:15h
Speaker: Paul Beck (Instituto de Astrofisica de Canarias)
Place: Sala Alberto Lobo

Asteroseismology is a powerful tool to study structure and dynamics of the stellar interior as well as their evolution. Such analysis can be done for thousands of stars in differing evolutionary stages from data of unprecedented photometric quality, provided by the NASA Kepler space telescope. In particular, the study of stochastic, solar-like oscillators in combination with high-resolution ground-based spectroscopy has led to numerous breakthroughs in our understanding of the stellar structure and evolution of solar-like stars and is an important tool to characterize the host stars of exoplanets.

In this talk, the principles of asteroseismology of solar-like oscillators will be discussed on the basis of case studies. We first view the best studied case, the Sun. On the main sequence, solar-analogue stars provide a treasure trove of high-quality oscillation spectra which provide besides mass and radius also information on age, activity cycles, etc. Combined with complimentary data, such as activity proxies, surface rotation rate or lithium abundances allow to draw a comprehensive picture of stars like our Sun. Solar-like oscillations are also found further away from the main sequence, in the more advanced evolutionary phases of the sub- and red-giant branch. Due to a characteristic in the oscillation properties, we can use seismology to look even deeper into the stars and ultimately study the properties of the core with seismic techniques.

Finally, an outlook to the forthcoming space missions, such as NASA TESS and ESA PLATO will be given and how they will influence the future of asteroseismology and the search for exoplanets.
15
March 2019

Chemical Complexity in Space and Earth Induced by Solid State Surfaces. Investigations by means of Quantum Chemistry


Start: 12:15h
Speaker: Albert Rimola (Chemistry Department, UAB)
Place: Sala Alberto Lobo

Our universe is molecularly rich [1-3], comprising from the most essential molecules (such as H2, H2O and NH3), passing through complex organic molecules (namely, COMs, molecules between 6 – 13 atoms where at least one is C rendering its organic character), reaching more evolved complex organic compounds,…
Start: 12:15h
Speaker: Albert Rimola (Chemistry Department, UAB)
Place: Sala Alberto Lobo

Our universe is molecularly rich [1-3], comprising from the most essential molecules (such as H2, H2O and NH3), passing through complex organic molecules (namely, COMs, molecules between 6 – 13 atoms where at least one is C rendering its organic character), reaching more evolved complex organic compounds, in which in some cases are of biological relevance, such as amino acids, nucleobases and sugars. Formation of early Solar-type systems involves successive steps, mainly represented by the prestellar, protostellar, protoplanetary disk, and planetesimal and planet formation phases. This evolution goes hand-in-hand with an increase of the molecular complexity, in which more complex molecules form at each step [4]. The usual interpretation of the complex scenario of molecular reactions occurring in space is through a cascade of gas-phase reactions [5]. Nevertheless, it has since long recognized, with kinetic models, that gas-phase process alone cannot justify the abundance in the universe of even the simplest molecule, H2, but resort to reactions occurring on cosmic grain surfaces is mandatory to reconcile prediction with observation [6]. Accordingly, a key role of the chemical complexity is also played by cosmic solid state materials, as their surfaces provide catalytic sites that favor pivotal chemical reactions. A possible fate of the cosmic biomolecules is to reach Earth through meteorites or comets to become one of the building blocks for the formation of the pristine biopolymers. Biopolymer formation is very difficult, as these reactions are thermodynamically disfavoured in water with high kinetic barriers [7]. However, it has been long proposed that naturally-occurring minerals could have played a key role favouring these reactions, as they present specific surface sites that can adsorb and concentrate prebiotic organic compounds [8,9]. Computational quantum chemical methods may help in clarifying possible reactive channels towards molecule formations using proper atomistic structural models of the systems (including the extended surfaces), as they allow us to characterize chemical paths along the potential energy surfaces.In the talk, we discuss few examples from our own work for simulating essential molecules and COMs on interstellar grains as well as formation of polypeptides via condensation reaction of amino acids on mineral surfaces.
Institute of Space Sciences (IEEC-CSIC)

Campus UAB, Carrer de Can Magrans, s/n
08193 Barcelona.
Phone: +34 93 737 9788
Email: ice@ice.csic.es
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An institute of the Consejo Superior de Investigaciones Científicas

An institute of the Consejo Superior de Investigaciones Científicas
Affiliated with the Institut d'Estudis Espacials de Catalunya

Affiliated with the Institut d'Estudis Espacials de Catalunya