All future seminars

Number of entries: 4

31
May 2017

Cherenkov Telescope Arrays for Optical Astronomy: Intensity interferometry and imaging of stellar surfaces


Start: 12:00h
Speaker: Dainis Dravins (Lund Observatory)
Place: Sala Alberto Lobo

Optical imaging with microarcsecond resolution will reveal details on and around stellar surfaces but requires kilometer-scale interferometers.  Intensity interferometry, electronically connecting independent telescopes, has an error budget that relates to electronic time resolutions of nanoseconds…
Start: 12:00h
Speaker: Dainis Dravins (Lund Observatory)
Place: Sala Alberto Lobo

Optical imaging with microarcsecond resolution will reveal details on and around stellar surfaces but requires kilometer-scale interferometers.  Intensity interferometry, electronically connecting independent telescopes, has an error budget that relates to electronic time resolutions of nanoseconds and light-travel distances of centimeters or meters (rather than scales of an optical wavelength), circumventing issues of atmospheric turbulence.  Once pioneered by Hanbury Brown and Twiss, digital versions of this quantum-optical technique have now been demonstrated in the laboratory, reconstructing diffraction-limited images from measurements over hundreds of optical baselines.  Baselines up to a few km will soon become available with the Cherenkov Telescope Array (primarily built for gamma-ray studies), thus realizing an optical interferometer in software, somewhat analogous to that of ALMA at radio wavelengths.
09
June 2017

Obtaining precipitation information from Polarimetric GNSS radio occultation observables


Start: 12:00h
Speaker: Ramon Padullés Rulló (Institute of Space Sciences)
Place: Sala de Conferencias Alberto Lobo

The Earth observation satellite PAZ will be finally launched by the end of this year, thanks to the agreement signed between Hisdesat (the owner of the satellite) and SpaceX. PAZ will test the new Polarimetric Radio Occultation observation concept. During the last years, the theoretical framework of…
Start: 12:00h
Speaker: Ramon Padullés Rulló (Institute of Space Sciences)
Place: Sala de Conferencias Alberto Lobo

The Earth observation satellite PAZ will be finally launched by the end of this year, thanks to the agreement signed between Hisdesat (the owner of the satellite) and SpaceX. PAZ will test the new Polarimetric Radio Occultation observation concept. During the last years, the theoretical framework of the concept has been set, the feasibility of the technique has been proven and some applications have been investigated. In this talk I will briefly review the most relevant aspects of the technique, and I will focus on the characterization of the signal, describing the effects that electromagnetic waves emitted from the GPS undergo in their way to the receiver. A detailed set of simulations has been performed in order to test the performance of the retrieval algorithms, that allow us to obtain precipitation information from the differential phase measurements.  
16
June 2017

Anatomy of the archetypal protostellar shock L1157-B1


Start: 12:00h
Speaker: Gemma Busquet (Institut de Ciències de l'Espai (IEEC-CSIC))
Place: Sala Alberto Lobo, ICE

During the earliest protostellar stages of their formation, young stars generate fast collimated winds (or jets) which impact the parent molecular cloud through shock fronts.  Protostellar shocks play a crucial role in the chemical evolution of star-forming clouds because they induce in the surrounding…
Start: 12:00h
Speaker: Gemma Busquet (Institut de Ciències de l'Espai (IEEC-CSIC))
Place: Sala Alberto Lobo, ICE

During the earliest protostellar stages of their formation, young stars generate fast collimated winds (or jets) which impact the parent molecular cloud through shock fronts. 
Protostellar shocks play a crucial role in the chemical evolution of star-forming clouds because they induce in the surrounding medium large variation of temperature and density, which can locally activate endothermic gas-phase reactions, ionization processes, and evaporation/erosion of dust grains and their icy mantles. The nature and properties of these shocks and jets are a source of major debate. The launching mechanism of the jet, the role of the magnetic field, or the shock properties (i.e. ionization fraction) are some of the key questions that remain to be answered
Associated with a low-mass Class 0 protostar, L1157-B1 is a protostellar chemically rich bow-shock that has been extensively studied from the infrared to millimeter wavelengths.
In this talk I’ll review the most relevant aspects of protostellar shocks and for the particular case of the shock laboratory L1157-B1. I’ll also present the recent work we are conducting with several telescopes to obtain a comprehensive view of the bow-shock structure and shock chemistry. 
26
July 2017

The physics and astrophysics of merging neutron-star binaries


Start: 12:00h
Speaker: Prof. Luciano Rezzolla (University of Frankfurt)
Place: Sala Alberto Lobo

I will argue that if black holes represent one the most fascinating implications of Einstein's theory of gravity, neutron stars in binary system are arguably its richest laboratory, where gravity blends with astrophysics and particle physics. I will discuss the rapid recent progress made in modelling…
Start: 12:00h
Speaker: Prof. Luciano Rezzolla (University of Frankfurt)
Place: Sala Alberto Lobo

I will argue that if black holes represent one the most fascinating implications of Einstein's theory of gravity, neutron stars in binary system are arguably its richest laboratory, where gravity blends with astrophysics and particle physics. I will discuss the rapid recent progress made in modelling these systems and show how the inspiral and merger of a binary system of neutron stars is more than a strong source of gravitational waves. Indeed, while the gravitational signal can provide tight constraints on the equation of state for matter at nuclear densities, the formation of a black-hole--torus system can explain much of the phenomenology of short gamma-ray bursts, while the the ejection of matter during the merger can shed light on the chemical enrichment of the universe.
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An institute of the Consejo Superior de Investigaciones Científicas

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