Calendar
stanza Google Meet: https://meet.google.com/sxz-cctp-tsc
Speaker: Darius Modirrousta-Galian (UNIPA)
Title: RAPOC: the Rosseland and Planck opacity converter
A user-friendly and fast opacity program for Python
Abstract:
We present a novel code that converts the widely-used wavelength-dependent opacities of gaseous species into Rosseland and Planck mean opacities. RAPOC (Rosseland and Planck Opacity Converter) is a straightforward and efficient code that makes use of ExoMol data as well as any other user-defined data, provided that it is within the correct format. Furthermore, RAPOC has the useful ability of rapidly interpolating between discrete data points, therefore allowing for a complete incorporation within atmospheric models. In this paper we present the RAPOC code and compare its calculated Rosseland and Planck mean opacities with other values within the literature.
stanza Google Meet: https://meet.google.com/sxz-cctp-tsc
Speaker: Sabina Ustamujiic (UNIPA)
Titolo: Modeling the mixed-morphology supernova remnant IC 443
Abstract: IC 443 is a mixed-morphology (MM) SNR located in a quite complex environment, interacting with atomic and molecular clouds. We investigated the origin of the morphology and multi-thermal X-ray emission observed in SNR IC 443 through the study of the effect of the inhomogeneous ambient medium in shaping its observed structure. We developed a 3D hydrodynamic model, which describes the interaction of the SNR with the environment, parametrized in agreement with the results of the multi-wavelength data analysis. We performed an ample exploration of the parameter space describing the model and, from the simulations, we synthesized the X-ray emission maps and spectra and compared them with actual X-ray data collected by XMM-Newton. Our model explains the origin of the complex X-ray morphology of SNR IC 443 in a natural way, with the ability to reproduce, for the first time, most of the observed features, including the centrally-peaked X-ray morphology (characteristic of MM SNRs) when considering the origin of the explosion at the position where the pulsar wind nebula CXOU J061705.3+222127 was at the time of the explosion. The observed inhomogeneous ambient medium is the main property responsible for the complex structure and the X-ray morphology, resulting in a very asymmetric distribution of the ejecta due to the off-centered location of the explosion inside the cavity formed by the clouds.
3 persone
Stanza Google Meet: meet.google.com/sxz-cctp-tsc
Speaker: Gabriele Cozzo (UniPA)
Titolo: “Study of the accretion phenomena of T Tauri stars with the GRAVITY instrument”
Abstract
Accretion through circumstellar disks plays a fundamental role in the process of star formation. Characterising how accretion works in the context of young stellar objects will also help us to constrain the properties of the regions in which planets form and migrate. The accretion mechanism in low-mass pre-main-sequence stars (T Tauri Stars) is driven by the stellar magnetic field, which disrupts the disk at the magnetospheric radius, generally located at scales of order a few stellar radii. Almost bipolar field lines channel the material from the disk to the star, which ends with shocking at the stellar surface at near free-fall velocities. From decades, the technological improvement has driven the development of new ways to probe faint and distant objects as Classical T Tauri stars are and disentangle the multifarious physical processes involved in sustaining the stars’ evolution. The state-of-the-art in interferometry science has indeed attained unprecedented capabilities in terms of angular resolutions. This new potentiality, coupled with the purpose to understand the innermost regions of CTTSs, deserves a new approach to interpret data and manipulate information. This work addresses the ambition to lay the foundation of a new framework of observational data interpretation that sheds light on the capabilities of new-class interferometric instruments, like the Very Large Telescope Interferometer, in sampling and disentangling the physical conditions in which a star is born.
Stanza Google meet: https://meet.google.com/sxz-cctp-tsc
Speaker: Ruggero Biondo (UniPA)
Titolo: Tracing the ICME plasma with a MHD simulation
Abstract:
The determination of the chemical composition of Interplanetary Coronal Mass Ejection (ICME) plasma is an open issue. More specifically, it is not yet fully understood how remote sensing observations of the solar corona plasma during solar disturbances evolve in plasma properties measured in-situ away from the Sun. The ambient conditions of the background interplanetary plasma are important for space weather because they influence the evolutions, arrival times and geo-effectiveness of the disturbances. The Reverse In-situ and MHD APproach (RIMAP) is a technique to reconstruct the heliosphere on the ecliptic plane (including the magnetic Parker spiral) directly from in situ measurements acquired at 1 AU. It combines analytical and numerical approaches, preserving the small-scale longitudinal variability of the wind flow-lines. In this work, we use RIMAP to test the interaction of an ICME with the interplanetary medium. We model the propagation of a homogeneous non-magnetized (i.e., with no internal flux rope) cloud starting at 800 km/s at 0.1 AU out to 1.1 AU. Our 3D MHD simulation made with the PLUTO MHD code shows the formation of a compression front ahead of the ICME, continuously driven by the cloud expansion. Using a passive tracer, we find that the initial ICME material does not fragment behind the front during its propagation, and we quantify the mixing of the propagating plasma cloud with the ambient solar wind plasma, which can be detected at 1 AU.
Speaker: Valerio Fardella (UNIPA)
Titolo: L’analisi delle atmosfere degli esopianeti. Come e perché.
relazione di Laurea triennale,
indirizzo Google Meet: meet.google.com/sxz-cctp-tsc
Abstract:
La composizione chimica dell’atmosfera di un esopianeta può aiutare a capire quale siano la composizione e, a volte, l’evoluzione passata dell’esopianeta. L’atmosfera, se è presente, può essere osservata quando il pianeta transita davanti la sua stella. Lo spettro in trasmissione che si osserva in tal modo contiene informazioni sulle abbondanze presenti nell’atmosfera. Tuttavia, alcuni fenomeni fisici e chimici possono ostacolare significativamente la rilevazione di queste abbondanze. In questa presentazione vengono mostrati alcuni aspetti dell’osservazione ed analisi di uno spettro in trasmissione di un’atmosfera esoplanetaria e alcune delle informazioni che è possibile trarre da esso.