Search results for "solar corona"
showing 10 items of 28 documents
Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe–Metis/Solar Orbiter Observations
2022
Abstract The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R ⊙ above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local p…
The EM(T) of stellar coronae
2010
Studying the solar corona, due to its vicinity, is the starting point to understand stellar activity. The emission measure distribution vs temperature, EM(T), is a useful tool to study coronal plasmas, in fact it allows: to investigate the energy balance of coronal plasmas, to easily compare different stars, and also to compare the solar corona to that of other active stars irrespective of the very different observing techniques. The EM(T) of the solar corona differs significantly, in terms of average plasma temperatures, peak temperatures, and total emission measure, with respect to that of active stars. In this work it is discussed how the evaluation of the EM(T) of the solar corona, and …
SphinX soft X-ray spectrophotometer: Science objectives, design and performance
2011
The goals and construction details of a new design Polish-led X-ray spectrophotometer are described. The instrument is aimed to observe emission from entire solar corona and is placed as a separate block within the Russian TESIS X- and EUV complex aboard the CORONAS-PHOTON solar orbiting observatory. SphinX uses silicon PIN diode detectors for high time resolution measurements of the solar spectra in the range 0.8–15 keV. Its spectral resolution allows for discerning more than hundred separate energy bands in this range. The instrument dynamic range extends two orders of magnitude below and above these representative for GOES. The relative and absolute accuracy of spectral measurements is e…
Dynamic Temperature Structure of the Corona
2012
The solar corona is heated to million degrees and information about the temperature structure is a key to understand the heating mechanisms. Although it is not easy to measure, the temperature looks to be remarkably steady in the solar corona and in active regions outside of transient events, like flares. On the other hand, there is strong evidence of multi-thermal structures, out of equilibrium for most of the time. Is there a way to obtain a coherent scenario? The secret might be in the fine structuring of the corona, and SDO is providing new and important information on this issue.
Are Coronae of Late‐Type Stars Made of Solar‐like Structures? The X‐Ray Surface Flux versus Hardness Ratio Diagram and the Pressure‐Temperature Corre…
2004
This work is dedicated to the solar-stellar connection, i.e., the close similarity of the Sun and late-type stars; in particular, this work shows that stellar coronae can be composed of X-ray-emitting structures similar to those present in the solar corona. To this end we use a large set of ROSAT PSPC observations of late-type stars of all spectral types and activity levels and a large set of solar X-ray data collected with Yohkoh SXT. Solar data have been analyzed and formatted to study the Sun as an X-ray star; they include observations of the solar corona at various phases of the solar cycle and data on various kinds of X-ray coronal structures, from flares to the background corona, i.e.…
Coronal Loops: Observations and Modeling of Confined Plasma
2010
Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the review is divided into two separate but not independent sections: the first illustrates the observational framework, the second reviews the theoretical knowledge. Quiescent loops and their confined plasma are considered, and therefore topics such as loop oscillations and flaring loops (except for non-solar ones which provide information on stellar loops) are not specifically addressed here. The observational section discusses loop classification and popula…
Models and data analysis tools for the Solar Orbiter mission
2020
All authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.; Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.; Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.; Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi, N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla, T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.; Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.; Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.; Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.; Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot, V.; Georgoulis, M. K.; Gilbe…
Data-driven numerical simulations of the Parker Spiral and interplanetary propagation of solar transients
2023
The accurate reconstruction of the plasma and magnetic field parameters in the ambient interplanetary medium is fundamental to reproduce the interplanetary propagation of solar disturbances such as solar energetic particles (SEPs), stream and corotating interaction regions (SIRs and CIRs), and coronal mass ejections (CMEs), both for understanding the physics of these phenomena and for applications in space weather forecasting. The small-scale features of the ambient solar wind, in fact, affect the evolution, arrival times, and geo-effectiveness of solar transients. The Reverse In situ and MHD Approach (RIMAP) is a hybrid analytical-numerical method to reconstruct the heliosphere on the ecli…
Hinode/XRT Diagnostics of Loop Thermal Structure
2008
We investigate possible diagnostics of the thermal structure of coronal loops from Hinode/XRT observations made with several filters. We consider the observation of an active region with five filters. We study various possible combinations of filter data to optimize for sensitivity to thermal structure and for signal enhancement.
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.