Dear all,
please find a preprint of a paper recently accepted for publication in A&A at the link:
http://arxiv.org/abs/1402.6554
Best regards
Fabio & Antonino
Thermal structure of hot non-flaring corona from Hinode/EIS
A. Petralia, F. Reale, P. Testa, G. Del Zanna
Abstract In previous studies a very hot plasma component has been diagnosed in solar active regions through the images in three different narrow-band channels of SDO/AIA. This diagnostic from EUV imaging data has also been supported by the matching morphology of the emission in the hot Ca XVII line, as observed with Hinode/EIS. This evidence is debated because of unknown distribution of the emission measure along the line of sight. Here we investigate in detail the thermal distribution of one of such regions using EUV spectroscopic data. In an active region observed with SDO/AIA, Hinode/EIS and XRT, we select a subregion with a very hot plasma component and another cooler one for comparison. The average spectrum is extracted for both, and 14 intense lines are selected for analysis, that probe the 5.5 < log T < 7 temperature range uniformly. From these lines the emission measure distributions are reconstructed with the MCMC method. Results are cross-checked with comparison of the two subregions, with a different inversion method, with the morphology of the images, and with the addition of fluxes measured with from narrow and broad-band imagers. We find that, whereas the cool region has a flat and featureless distribution that drops at temperature log T >= 6.3, the distribution of the hot region shows a well-defined peak at log T = 6.6 and gradually decreasing trends on both sides, thus supporting the very hot nature of the hot component diagnosed with imagers. The other cross-checks are consistent with this result. This study provides a completion of the analysis of active region components, and the resulting scenario supports the presence of a minor very hot plasma component in the core, with temperatures log T > 6.6.
Dear colleagues,
We are pleased to announce the Seventh Coronal Loops Workshop will be held at the Centre for Mathematical Sciences, University of Cambridge, UK, from the 21 to 23 July 2015.
Registration and Abstract Submission details and deadlines to follow.
The loops workshops are a series of highly focused workshops dealing with the observation and modeling of magnetically confined plasma. The programme and invited speakers are as follows:
Loops7 - Heating of the Magnetically Closed Corona
Session 1 - Coronal Heating: Global Active Region Models and Mechanisms
- heating mechanisms: Mahboubeh Asgari-Targhi - global AR models (visualizations etc.): Ignaki Ugarte-Urra - beyond hydro or MHD modeling: Tony Arber
Session 2 - Transition Region-Corona Connection
- observations vs theory; chromosphere: Bart De Pontieu - classical TR vs low lying cool loops: Pia Zacharis - role of spicules: Tiago Pereira
Session 3 - Fine Scale Structure and Non-equilibrium Processes
- fine-scale structure of loops: Patrick Antolin - current sheets and turbulence: Bruno Coppi - diagnostics – developments and limitations: Peter Young - advances in treating non-equilibrium processes: Jaro Dudik
Session 4 – Wrap up session ‘What doesn’t match up between theory and observations?’ TBD
The review talks will introduce these topics, highlighting recent progress and unresolved questions. Both observational and theoretical aspects will be covered during each session by contributed talks.
The workshop's main goal is to encourage discussion among the participants. For this reason the number of talks will be limited, while the poster sessions will be long enough to allow time to view and discuss the others participants' work. We strongly encourage young researchers to participate.
PLEASE NOTE: Only abstracts directly relevant to the main focus of the workshop will be accepted.
For further information please check our web site at: http://www.damtp.cam.ac.uk/user/astro/cl7/index.html
Scientific Organizing Committee: Helen Mason (chair), UK Caroline Alexander, USA Inigo Arregui, Spain Stephen Bradshaw, USA David Brooks, USA/Japan Leon Golub, USA Viggo Hansteen, Norway Susanna Parenti, Belgium
Local Organizing Commitee: Giulio Del Zanna (Chair) Helen Mason Andrew Hillier Vanessa Polito Stephen Bradshaw Jaroslav Dudik Durgesh Tripathi Virginia Mullins (Administrative Assistant)
Best wishes, helen
loops@solar.physics.montana.edu