Search results for "Astrofisica"
showing 10 items of 481 documents
MHD Modeling of Accretion Processes in Young Stars with the PLUTO Code
2008
As shown by observations, many young stars (age<5-10 Myr) harbor a circumstellar disk and accrete material from it through the star-disk magnetosphere. Despite the large amount of observational data in the infrared, optical and X-ray bands, different issues regarding star-disk interactions are still yet open. Many of these issues need detailed physical models of the star-disk system for a better insight. To this end, we are developing a model describing the interaction between the accreting material and the star atmosphere, using the 3D Magneto-HydroDynamical (MHD) code PLUTO developed at the University of Torino. We plan to perform a set of demanding simulations on the PI2S2 Grid infrastru…
Modeling SNR shock waves expanding through the magnetized inhomogeneous interstellar medium
2009
We review our recent results on the MHD modeling of supernova shock waves propagating through the magnetized and inhomogeneous ISM. We explore the role of different physical processes simultaneously at work, namely magnetic-field-oriented thermal conduction, radiative cooling and MHD effects, in determining: 1) the mass and energy exchanges between different phases of the ISM and 2) the morphology of supernova remnants as observed in different bands. Our projects required an advanced 3D MHD code for parallel computers, FLASH, and high-performance computing. We discuss the results derived from the analysis of the local interaction of strong shocks with inhomogeneities of the ISM, and those d…
Modeling of Fine and Dynamic Structuring of Coronal Loops
2012
TES microcalorimeter for IXO: From focal plane to anticoincidence detector
2009
The high resolution spectroscopy provides a unique technique to extract fundamental information in X-ray Astrophysics and Cosmology. In order to exploit at the best the capability of carrying out spectroscopy of faint sources, great care must be taken to reduce the background in the main detector. In this paper, we will present the working principle of a TES (Transition Edge Sensor) Microcalorimeter, its application for fine spectroscopy and a novel anticoincidence technique , based itself on a TES detector. Recent results from the first sample of the IXO-anticoincidence detector will be also shown.
Accretion Shocks in Young Stars: the Role of Local Absorption on the X-ray Emission
2015
We investigate the X-ray emission from accretion shocks in classical T Tauri stars, due to the infalling material impacting the stellar surface. Several aspects in both observations and models of the accretion process are still unclear: the observed X-ray luminosity of the post-shock plasma is below the predicted value, the density vs temperature structure of the shocked plasma, with increasing densities at higher temperature, is opposite of what expected from simple accretion shock models. To address these issues we performed numerical magnetohydrodynamic simulations describing the impact of an accretion stream onto the stellar surface and considered the local absorption due to the surroun…
Asymmetric Twisting of Coronal Loops
2023
The bright solar corona entirely consists of closed magnetic loops rooted in the photosphere. Photospheric motions are important drivers of magnetic stressing, which eventually leads to energy release into heat. These motions are chaotic and obviously different from one footpoint to the other, and in fact, there is strong evidence that loops are finely stranded. One may also expect strong transient variations along the field lines, but at a glance, coronal loops ever appear more or less uniformly bright from one footpoint to the other. We aim to understand how much coronal loops can preserve their own symmetry against asymmetric boundary motions that are expected to occur at loop footpoints…
The mass determination challenge for exoplanetary science
2023
The mass of an exoplanet is a key parameter for the characterisation of the internal structure of a planet, as well as the study of the formation and the evolution of the planet, and its atmosphere. The radial velocity technique allows for measuring the planetary mass from the radial velocity variation of its parent star. However, limitations in the property determination of exoplanets, particularly in their masses, can arise from various sources especially from astrophysical noise due to stellar variability, caused by magnetic activity, which affects the detection and characterisation of exoplanets. This PhD thesis aims to understand the impact of our knowledge of the planetary mass in the…
ANALYSIS OF SMALL-SCALE VARIABILITY OF CORONAL OBSERVATIONS WITH THE HINODE/X-RAY TELESCOPE
2012
The Space Weather X-Ray spectrometer for the Helianthus sub-L1 mission with solar photonic propulsion
2022
Copyright 2022 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited. Helianthus is a phase A study of a space weather station with solar photonic propulsion. The scientific payload will be made of: an X-ray spectrometer to detect solar flares; SailCor, a coronagraph with a wide field of view; a plasma analyzer; a magnetometer. The maximum allowed mass for the entire scientific payload shall not exceed 5 kg. The two imaging devices…
Coronal structure and dynamics
2012
Recent spatial solar missions, such as Hinode and Solar Dynamics Observatory, reveal a more and more highly structured and dynamic corona, with an increasing importance and debate. The connection of structure and dynamics to coronal heating is fundamental. Observations and evidence of fine coronal structuring, e.g. moss and emission measure distributions, and dynamics, e.g. Doppler shifts, spicules, are discussed and compared to current vision and models. Open questions and future perspectives are outlined to conclude.