Archives Séminaires 2018-2019

Séminaire

Séminaire IPAG de Peter Schilke (Köln University), jeudi 11 juillet 2019 à 11h00, salle Manuel Forestini

A significant fraction of stars, including our sun, have formed in clusters containing high-mass stars. Yet, the low-mass population in such clusters remain poorly studied. I will present an analysis of ALMA observations of two high-mass star containing cluster regions, and discuss statistical properties of the clusters, such as the clump mass function, distances and sub-clumping. Particular emphasis is put on the discussion of biases, which cause a considerable uncertainty in the shape of (…)

Séminaire doctorant

Séminaire doctorant de Joan Enrique Romero (IPAG), jeudi 4 juillet 2019 à 11h00, salle Manuel Forestini

Interstellar complex organic molecules (iCOMs) have a great importance for the astronomical community since they can be used as tracers for the physical conditions of the interstellar medium (ISM).
Moreover, in the last years they have gained a lot of attention since they could have played a role in the origin of life on Earth as they could have been inherited by small bodies of the Solar System, e.g. carbonaceous chondrites and comets [Caselli & Ceccarelli 2012].
Thus, understanding (…)

Séminaire

Séminaire IPAG de Simon Borgniet (LESIA), jeudi 27 juin 2019 à 11h00, salle Manuel Forestini

Classical Cepheid pulsators have been primary galactic and extragalactic distance indicators for a century, thanks to their Period-Luminosity (P-L) relationships. They have thus tremendously contributed to precision cosmology. However, the accuracy of the Cepheid P-L relations is now inadequate, and an independent calibration of Cepheid distances is required. An elegant and quasi-geometrical way of measuring distances of bright, nearby Milky Way (MW) Cepheids is the Parallax-of-Pulsation (…)

Séminaire

Séminaire IPAG de Beth Biller (Edinburgh), jeudi 20 juin 2019 à 11h00, salle Manuel Forestini

Direct detection, and direct spectroscopy in particular, have great potential for advancing our understanding of extrasolar planets.
In combinations with other methods of planet detection, direct imaging and spectroscopy will allow us to eventually : 1) fully map out the architecture of typical planetary systems and 2) study the atmospheric properties of exoplanets in depth.
I will discuss in particular the constraints on the distributions of wide giant exoplanets placed by the current (…)

Séminaire

Séminaire IPAG de Roman Rafikov (DAMTP Cambridge), jeudi 13 juin 2019 à 11h00, salle Manuel Forestini

Direct imaging of a number of protoplanetary disks, as well as recent sub-mm observations with ALMA have revealed a plethora of structures in the disks, ranging from grand design spirals to multiple axisymmetric gaps and rings.
In this observationally-motivated talk I will provide a theoretical overview of the different ideas for the origin of these structures.
I will first focus on the spirals, their characteristics and ideas for their origin.
I will also talk about their linear and (…)

Séminaire

Séminaire IPAG de Martin Bizzarro (University of Copenhagen), jeudi 6 juin 2019 à 11h00, salle Manuel Forestini

Elucidating the timescales of solid formation in the early Solar System is critical for a better understanding of disk processes.
Although short-lived radionuclides such as 26Al can theoretically provide high resolution ages, such decay systems critically depend on the disputed assumption of homogeneous distribution of their parent nuclides. A such, only the decay of U to Pb can provide assumption free ages with sufficiently high resolution to determine the timing of individual meteoritic (…)

Séminaire

Séminaire IPAG de Rosine Lallement (Meudon), jeudi 23 mai 2019 à 11h00, salle Manuel Forestini

The Gaia space mission measurements, parallaxes, photometry and stellar spectroscopy, are gradually leading us to a realistic three-dimensional representation of the Galaxy, especially improved by the joint use of massive stellar surveys from the ground. I will focus on the following aspects : advances in 3D tomography of interstellar dust clouds, based on parallaxes and visible and infrared photometric data (Gaia+2MASS). I will show recent dust maps extending to 3 kpc in the midplane and (…)

Séminaire

Séminaire IPAG de Kerri Donaldson Hanna (Oxford), jeudi 16 mai 2019 à 11h00, salle Manuel Forestini

Thermal infrared observations of Solar System bodies provide key insights into the physical and compositional properties of their surfaces. Thermal physical properties include surface temperatures, regolith and rock properties, and thermal inertia. Thermal infrared spectral measurements can be used to identify compositional units on planetary surfaces as rocks and minerals have diagnostic features across this wavelength region. In this talk, I will provide an overview of current spacecraft (…)

Séminaire

Séminaire IPAG de Susanne Wampfler (CSH Bern), jeudi 9 mai 2019 à 11h00, salle Manuel Forestini

Constraining the origin of different solar system materials is critical for understanding the formation and evolution of our solar system. One of the puzzling properties of our solar system is that the isotopic composition of volatile elements like nitrogen is heterogeneous among the solar system bodies. For instance, the terrestrial planets, comets, and meteorites are significantly enriched in the rare 15N-isotope compared to the Sun and the gas giants. While the existence of this isotopic (…)

Séminaire doctorant

Séminaire IPAG de Leila Gabasova (IPAG), jeudi 2 mai 2019 à 11h30, salle Manuel Forestini

The 2015 New Horizons flyby of the Pluto system returned a wealth of data, including hyperspectral data from the spacecraft’s LEISA instrument. This will allow us to create a detailed compositional map ; however, multiple processing steps are required in order to make use of the data. This includes spatial registration of multiple datasets to create a combined global map, and the resolution of high-dimensional inverse modeling problems to extract quantitative data on the surface structure (…)