Found 6 talks width keyword scattering

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Tuesday September 20, 2022
Dr. Asif ud-Doula
Penn State University

Abstract

Massive stars (at least eight times as massive as the Sun) possess strong stellar winds driven by radiation. With the advent of the so called MiMeS collaboration, an increasing number of these massive stars have been confirmed to have global magnetic fields. Such magnetic fields can have significant influence on the dynamics of these stellar winds which are strongly ionized. Such interaction of the wind and magnetic field can generate copious amount of X-rays, they can spin the star down, they can also help form large scale disk-like structures. In this presentation I will discuss the nature of such radiatively-driven winds and how they interact with magnetic fields.

https://youtu.be/jKmifm17bno


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Tuesday July 20, 2021
Dr. Sergey Yurchenko
University College of London

Abstract

The ExoMol project (www.exomol.com) provides comprehensive spectroscopic data (line lists) for the study of atmospheres of exoplanets and other hot bodies.  These line lists serve as input for models of radiative transport through hot atmospheres and are useful for a variety of terrestrial applications. The basic form of the database is extensive line lists; these are supplemented with partition functions, state lifetimes, cooling functions, Landé g-factors, temperature-dependent cross sections, opacities, k-coefficients and pressure broadening parameters. Currently containing 80 molecules and 190 isotopologues totaling over 700 billion transitions, the database covers infrared, visible and UV wavelengths. The field of the HR spectroscopy of exoplanets is growing extremely fast and urgently demands molecular data of high precision. Failure to detect molecules in atmospheres of exoplanets is often attributed to the lack of the underlying quality of
the line positions.  These developments have led us to begin a systematic attempt to improve the accuracy of the line positions for the line lists contained in the database. Our new ExoMolHD project aims to provide comprehensive line lists to facilitate their use in characterization of exoplanets using high resolution Doppler shift spectroscopy. Progress on this objective will be presented.


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Tuesday June 8, 2021
Dr. Hector Socas-Navarro
IAC

Abstract

In this talk I'll present results from a recent paper in which we have developed a new analysis technique for solar spectra based on artificial neural networks. Our first test applications yielded some unexpected and interesting results. The fine-scale network of temperature enhancements in the quiet middle and upper photosphere have a reversed pattern. Hot pixels in the middle photosphere, possibly associated with small-scale magnetic elements, appear cool at higher levels (log(tau)=-3 and -4), and vice versa. We also find hot arcs on the limb side of magnetic pores, which we interpret as the first direct observational evidence of the "hot wall" effect. Hot walls are a prediction of theoretical models from the 1970s which had not been observed until now.

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Tuesday May 25, 2021
Drs. Olga Mena
IFIC

Abstract

In this talk, we shall review the impact of the neutrino properties on the different cosmological observables. We shall also present the latest cosmological constraints on the neutrino masses and on the effective number of relativistic species. Special attention would be devoted to the role of neutrinos in solving the present cosmological tensions.


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Tuesday November 8, 2016
Dr. Karri Muinonen
University of Helsinki, Finland

Abstract

Series: XXVIII Canary Islands Winter School of Astrophysics: Solar System Exploration

Topic: Physical Properties of Asteroid Surfaces

Lecture 2: Novel spectrometric modeling

In his second talk, Dr. Muinonen focuses on multiple scattering, describing in detail processes such as the radiative transfer and coherent backscattering (RT-CB), particular cases with incoherent fields, and radiative transfer with reciprocal transactions (R2T2). He also presents very preliminar and recent results obtained by his team at the University of Finland on incoherent backscattering experimetns on millions of spherical particles. In this talk he also revisits space weathering in the context of radiative transfer theory and presents some experiments carried out with olivine.  


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Monday November 7, 2016
Dr. Karri Muinonen
University of Helsinki, Finland

Abstract

Series: XXVIII Canary Islands Winter School of Astrophysics: Solar System Exploration

Topic: Physical Properties of Asteroid Surfaces

Lecture 1: Introduction to asteroid UV-VIS-NIR spectrometry

In this first talk, Dr. Muinonen gives an introduction to polarimetry, photometry, and spectropolarimetry techniques and their application to the study of asteroid surfaces. The talk includes a description of the Shkuratov radiative transfer model and the use of Monte Carlo simulations to model radiative transfer for meteorite spectra. 


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