Pravidelné semináře pořádáme jednou měsíčně (říjen–červen, zpravidla první pondělí v měsíci) od 13 hod v seminární místnosti pracoviště Ondřejov.
03. 06. 2013
Observations of solar prominences with ALMA
Abstract: During the last decades, several studies had focused on the determination of the prominence temperatures. However, practically all of them were based on the analysis of mainly optical spectral line shapes which brings several difficulties and uncertainties, namely in cases when the spectral lines are optically thick. At the same time, the need for a reliable determination of the temperature in central coolest parts of quiescent prominences has grown as a result of new modeling efforts trying to understand the energy-balance conditions. Using the microwave spectra with a high spatial resolution offers the new possibility. We demonstrate that the fine structures in solar quiescent prominences can be well detected with the ALMA interferometer (Atacama Large Millimeter Array in Chile, joint project of ESO, USA and Japan). ALMA is going to be fully operational and a special hardware setup will allow soon the solar observations. We simulate the visibility of prominence fine structures, their brightness temperatures at various wavelengths and demonstrate the feasibility and usefulness of ALMA observations of solar prominences. Our basic approach is the conversion of high-resolution H-alpha coronagraphic images into the microwave spectral images. Finally, we apply the ALMA image-processing software CASA to our simulated images to see what the ALMA would detect in reality. We discuss various ways how to determine the prominence kinetic temperature from ALMA spectral images.
Dále pořádáme menší semináře jednotlivých oddělení:
Semináře slunečního oddělení
Každé úterý v 13:00 (září–červen, s výjimkou úterků po celoústavním semináři) v zasedací místnosti slunečního oddělení pracoviště Ondřejov.
11/06/2013, 13:00Force-free magnetic fields of toroidal shapesAbstract: Analytical solutions of linear force-free fields in toroidal geometry will be presented and their application to interpretation of magnetic cloud observations discussed. Magnetic clouds are flux ropes ejected from the Sun and propagate in the solar wind as a part of interplanetary coronal mass ejections.
Zářivě-(magneto)hydrodynamické semináře
Zpravidla 1x za 14 dní ve čtvrtek od 11 hod (říjen–červen) v zasedací místnosti slunečního oddělení pracoviště Ondřejov.
(informace nejsou k dispozici)
Semináře oddělení GPS
Zpravidla v knihovně pracoviště Praha–Spořilov v různé dny.
12. 08. 2013, 13:00Gymnasium Hubeneho 23, BratislavaX-ray dynamics measurements of the Tycho’s supernova remnant G120.1+01.4Abstract: Intel International Science and Engineering Fair 2013, international pre-college science competition.
In the following work we present X-ray dynamics measurements of the Tycho’s supernova remnant G120.1+01.4. We compare observations and spectra from 2005 and 2009 archived in XMM-Newton Science Archive in order to determine differences caused by collision with surrounding interstellar medium (ISM) as well as by remnant’s own expansion. We have calculated the azimuthal expansion of remnant’s edges to vary from 0.194 arcsec/yr to 0.438 arcsec/yr, while the highest values are found to have the azimuth of about 60° in the south-east and the lowest expansion overall is estimated on the north. Comparison of fluxes has shown that the highest estimated energy gain of 3.1 times was measured in reverse shock region around the azimuth of 300° in the energy range from 6.1 keV to 8 keV, whereas the highest energy loss was found to be in the same energy range in forward shock region with the azimuth of approximately 70° reaching 2.4 times lower energy compared with the values from 2005. We have also defined the most abundant heavy elements within energy scale from 200 eV to 8 keV, which are identified through spectral lines to be Fe XVIII (0.849 keV), Mg XI and XII (1.34 keV, 1.46 keV), Si XIII (1.83 keV), S XV (2.41 keV, 2.86 keV) and Ca XIX (3.84 keV).(Takes place at: Sporilov library)