Annual report - 2008
Mon, 2009-03-30 14:59, František Fárník
ESA-PECS : Progress Report on the Project No. 98030
"SOHO Observations and Data Analysis"
1.1 Observations with SOHO (campaigns etc.)
We have participated in or are currently involved in planning of the joint observations between SOHO, Hinode and other space instruments. Obtained data have been analyzed and the results published. The next joint campaign is envisaged for April-May 2009, dedicated to study of solar prominences/filaments.
1.2 SOHO data analysis
S. Gunár, P. Schwartz and P. Heinzel, in collaboration with B. Schmieder from Observatoire de Paris and U. Anzer from MPA Garching (Germany) have further analyzed the SUMER spectrum of a prominence obtained on May 25, 2005 during MEDOC campaign No. 15. The time-series of observed Lyman-??to Lyman-? lines (approx. 80 observational times for each line) were used for statistical analyses and comparisons with the synthetic Lyman spectrum obtained by our multi-thread modeling with the line-of-sight velocities (Gunár et al. 2008). We have statistically investigated several parameters, such as left to right peak intensity ratio, mean-peak to line-centre intensity ratio, Lyman-? to Lyman-??integrated intensity ratio and so on. We have obtained very promising agreement between synthetic and observed Lyman spectrum and we expect to publish these results within the following months.
G. Tsiropoula and K. Tziotziou (both from National Observatory of Athens, Greece) in collaboration with P. Schwartz (responsible for SOHO/CDS data calibration and line-profile analysis) and P. Heinzel studied frequencies and propagation velocities of waves in the quiet-Sun chromosphere and transition region applying wavelet power-analysis. They used observations of SOHO/CDS in 3 spectral lines formed in different heights in the chromosphere and transition region. They found similar frequencies and upward propagation of waves in network boundaries as some other authors did. But in the dark mottles the waves encounter a boundary and are refracted and reflected. These results have been published in A&A (Tsiropoula at al. 2009).
P. Schwartz with collaborators has continued the quantitative analysis of the spectra of transition-region lines as they have been collected in the SOHO/SUMER Atlas. Some preliminary results have been presented during the ESPM12 conference in Freiburg in September 2008.
M. Švanda, together with M. Klvaňa and M. Sobotka, continued the analysis of the large-scale flows (i.e. with characteristic sizes of 50 Mm and more) in the solar photosphere in the project, which was started in 2005. This topic is in particular important when dealing with the effects of the solar dynamo – the generation and redistribution of the magnetic fields on the Sun. Therefore, with cooperation with the Solar Oscillations Investigation group at Stanford University, USA, the leading group in the time-distance helioseismology field, we studied the effects of the local circulation flows around the active regions on the longitudinally averaged meridional flow. To investigate this issue, we determined the area-of-influence of each active region in the sample and masked these regions in the synoptic flow maps. We found (Švanda et al., 2008a) that the amplitude of the deviation of the mean meridional flow profile from the profile in the quiet Sun highly depends on the total flux in the particular active region. These deviations are up to 6 ms?1 – it is almost one third of the mean meridional speed velocity. After masking the active regions in the synoptic flow maps, significant part of the cyclic variations of the meridional flow profile remains, especially in higher latitudes. We speculated that at higher latitudes different mechanism probably operates, our results support the formation of the high-latitude large-scale counter-cell in the meridional flow. The hydrodynamical simulations of the solar convection zone do not reveal the observed properties (e.g. the spectrum of the convection) well. The simulations work badly especially in the last 10 Mm below the photosphere. We studied the depth dependence of the large-scale horizontal flows by comparing the surface-based measurements with the state-of-the-art time-distance helioseismic data at various depths. The surface measurements come from the tracking of supergranular structures in the full-disc Dopplergrams measured by SOHO/MDI, developed at AI and described in detail in Švanda et al. (2006). We found (Švanda et al., 2009) that the large-scale horizontal flows do not vary much within the depths of 0–10 Mm in the quiet Sun region and within the depths of 0–5 Mm in the regions occupied by the magnetic field. Incidentally, the theoretical models estimate the depth of the supergranules to be between 10 and 15 Mm, and the depth of the sunspots as the coherent thermodynamical structures seems to be around 5 Mm. If we assume that the used state-of-the-art helioseismic data are correct, then the supergranules, used as tracers in the surface measurements, may indeed be treated as the objects carried by the underlying large-scale velocity field. These results therefore put constraints on numerical simulations, which should reproduce the observed properties of the plasma motions in the large-scale. The supergranule-tracking method and all the results achieved with this method were summarised, presented, and discussed during ESPM12 meeting (Švanda et al., 2008b) in Freiburg (Germany). The method seems to have a power in measuring the large-scale plasma flow in the solar photosphere and can be applied to study many phenomena involved in the origin and changes of the solar activity.
1.3 Theoretical work related to SOHO data
S. Gunár, P. and P. Heinzel, in collaboration with U. Anzer and B. Schmieder, have studied the asymmetries of the synthetic hydrogen Lyman lines and the process responsible for their formation. To obtain the synthetic Lyman line profiles, we have used a multi-thread prominence fine-structure model consisting of identical 2D threads (Gunár et al. 2007) with randomly assigned line-of-sight velocities to each thread. Such synthetic Lyman spectrum exhibits substantial asymmetries of the line profiles, even though the LOS velocities of individual threads are only of the order of 10 km s-1. Moreover, our results indicate that the synthetic Lyman-? profiles may exhibit an opposite asymmetry to that of higher Lyman lines. This agrees with the observed profiles acquired by SUMER on May 25, 2005 during MEDOC campaign No. 15. These results are published in Gunár et al. (2008).
P. Heinzel and S. Gunár continued their development of the 2D transfer code for analysis of SOHO/SUMER hydrogen Lyman spectra.
P. Heinzel in collaboration with U. Anzer studied the differential emission measure (DEM) in solar prominences and discussed the prominence energy balance. For their study an empirical DEM obtained from SOHO/SUMER prominence reference spectrum of Parenti and Vial was used.
2. Hinode - observations and data analysis
A quiescent prominence was observed on 2007, April 25 in H? by the Hinode SOT, in X-rays by the Hinode XRT, and in the 195 ? channel by TRACE. Moreover, ground-based observatories (GBOs) provided calibrated H? intensities. Simultaneous extreme-UV (EUV) data were also taken by the Hinode EIS and SOHO/SUMER and CDS instruments. Dark prominence structure clearly seen in the TRACE and EIS 195 ? images is due to the prominence absorption in H I, He I, and He II resonance continua plus the coronal emissivity blocking due to the prominence and its void (cavity). The void clearly visible in the XRT images is entirely due to X-ray emissivity blocking. We use TRACE, EIS, and XRT data to estimate the amount of absorption and blocking. The H? integrated intensities independently provide us with an estimate of the H? opacity, which is related to the opacity of resonance continua as follows from our non-LTE radiative-transfer modeling. However, spatial averaging of the H? and EUV data has quite different nature, which must be taken into account when evaluating the true opacities. We demonstrate this important effect here for the first time. Finally, based on this multiwavelength analysis, we discuss the determination of the column densities and the ionization degree of hydrogen in the prominence. The results of this work are published in Heinzel et al. (2008). We applied a similar multi-wavelength analysis also for other prominences observed by SOHO/EIT and STEREO/EUVI in the 195 ? and 304 ? channels, by Hinode/XRT in soft X-rays and by Ondřejov HSFA spectrograph in H? between April 2007 and May 2008. Results for two of then were already presented at the “Solar Activity During the Onset of the Solar Cycle 24” workshop in USA. P. Schwartz tested the method of U. Anzer for estimation of the filling factor and asymmetrical distribution of the coronal emission in front of and behind the prominence. The method would improve our results from Heinzel et al. (2008). However, we found that SOHO/CDS observations of the MgX 624 ? line are not suitable for this method and it would be better to use SOHO/SUMER observations of this line during future observing campaigns.
3. Solar Orbiter
The results of the AO have not yet been announced by ESA. However, in the meantime a 3-rd Solar Orbiter Workshop was proposed and is currently being organized (to be held in May 2009 in Italy). P. Heinzel serves as the SOC member for this meeting. We are ready to continue our work on STIX and EUS proposals within the respective consortia.
4. Work presented on international meetings
P. Heinzel and S. Gunár participated in the second and third meeting at ISSI (International Space Science Institute) in Bern, Switzerland. This meeting was devoted to space observations of solar prominences, namely using the SOHO and Hinode satellites. P. Heinzel was the leader of spectroscopy group. The collaboration on various publications is in progress.
P. Heinzel has attended the SHINE meeting in Park City (USA) in June, where he has given an invited talk on results of the mass determination in prominences and filaments, using the space data. He also attended the astrophysical conferences in Bucharest (March) and in Belgrade (October), where he has given invited review talks on solar chromospheric structure and dynamics, showing new results from SOHO and Hinode.
P. Heinzel, S. Gunár, P. Schwartz, E. Dzifčáková, A. Kulinová and M. Švanda participated in the 12th European Solar Physics Meeting, September 8-12, Freiburg, Germany. P. Heinzel and S. Gunár together with U. Anzer (MPA-Garching, Germany) presented poster “Puzzling prominences: Are the high-resolution observations consistent with recent models?”. S. Gunár and P. Heinzel together with U. Anzer and B. Schmieder (Observatoire de Paris, Meudon, France) presented poster “On Lyman-line asymmetries in quiescent prominences”. P. Schwartz together with K. Tziotziou, G. Tsiropoula (both from National Observatory of Athens, Greece) and P. Heinzel presented poster “Contrast of Fine-scale Structures in a Quiet Sun Network Region”. M. Švanda presented contributed talk “Tracking of supergranules – does it make any sense?“ E. Dzifčáková together with A. Kulinová presented poster „Is It Possible to Diagnose the Non-thermal Distributions from EIS Spectra?“ A. Kulinová together with E. Dzifčáková presented poster „Diagnostic of the Non-thermal kappa-Distribution from Si III Lines“.
P. Schwartz participated in the “Solar Activity During the Onset of the Solar Cycle 24” workshop taking place in Napa CA, USA and held between December 7th and 12th. He presented there the poster „XUV Prominences and Surrounding Cavities”. This work was done together with F. Fárník, P. Heinzel and P. Kotrč.
M. Švanda participated in the Origin and Dynamics of Solar Magnetism meeting, 20–25 Jan 2008, Bern, Switzerland. Contributed talk by Švanda, Kosovichev, Zhao “Meridional flux transport on the Sun“, in the section devoted to young scientists.
M. Švanda participated at the conference „Magnetic Coupling Between the Interior and the Atmosphere of the Sun“, Bangalore, India, 2–6 Dec 2008. He presented there together with M. Sobotka, M. Klvaňa and V. Bumba (all AI) the poster “Dynamics of active regions revealed by tracking of Doppler features“.
At the “Second Hinode Science Meeting” in Boulder, USA, F. Farnik presented a joint paper (poster) “Prominence and its Coronal Cavity Observed by Hinode, TRACE and SOHO” prepared together with B. Schmieder (Observatoire de Paris), P. Schwartz, P. Heinzel, and S. Gunar from AI.
5. Activities proposed for 2009
Further involvement in the SOHO and Hinode observations and data analysis (e.g. publication of the statistical analysis by S. Gunár, P. Schwartz, P. Heinzel). In the theoretical field we will concentrate on the development of the models usable of the modeling of both prominence and filament fine structures. Such models require the 3D geometry and therefore we will work on the development of a 3D radiative transfer code.
We plan to continue with the multi-wavelength study of prominences observed by SoHO/EIT, Hinode/XRT and HSFA, of which the first particular results were already presented at the workshop “Solar Activity During the Onset of the Solar Cycle 24”. We plan to participate at the 3rd Hinode workshop which will take place in November in Tokyo and present complete results there.
We will propose a new observing campaign for prominences and filaments involving SOHO/CDS, SOHO/SUMER, Hinode and MSDP at Meudon Solar Tower together with the Ondřejov HSFA spectrograph. The novel aspect of these proposed observations would be that SUMER will observe not only the hydrogen Lyman series but also the MgX 624 ? line (previously observed by CDS).
During the postdoc stay at Max-Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, M. Švanda will participate on preparation of the pipelines for processing the data from Solar Dynamics Observatory (to be launched in the second half of 2009) with an extensive use of the SOHO data.
We plan our involvement in the Solar Orbiter project for which we should develop and manufacture electronic parts of the STIX instrument. We will participate in the 3-rd Solar Orbiter Workshop in Italy (in May).
7. List of publications
Anzer, U., Heinzel, P. 2008, A&A, 480, 537
Berlicki, A., Heinzel, P., Schmieder, B., Li, H. 2008, Modelling of the Flare Observed Above Sunspot Penumbra, poster 3.19 at the 12th European Solar Physics Meeting, published electronically
Berlicki, A., Heinzel, P., Schmieder, B., Li, H. 2008, A&A, 490, 315
Dzifčáková, E., Kulinová, A. 2008, Is It Possible to Diagnose the Non-thermal Distributions from EIS Spectra?, poster 3.63 at the 12th European Solar Physics Meeting, published on internet
Gunár, S., Heinzel, P., Anzer, U., Schmieder, B. 2008, A&A, 490, 307
Gunár, S., Heinzel, P., Anzer, U., Schmieder, B. 2008, On Lyman-line Asymmetries in Quiescent Prominences, poster 3.18 at the 12th European Solar Physics Meeting, published electronically
Heinzel, P. 2008, Understanding the Solar Chromosphere, Exploring the Solar System and the Universe. AIP Conference Proceedings, Volume 1043, pp. 238-244
Heinzel, P., Schmieder, B., Fárník, F., Schwartz, P., et al. 2008, ApJ, 686, 1383
Kulinová, A., Dzifčáková, E. 2008, Diagnostic of the Non-thermal kappa-Distribution from Si III Lines, poster 2.112 at the 12th European Solar Physics Meeting, published electronically
Labrosse, N., Schmieder, B., Heinzel, P., Gunar, S. 2008, Solar Prominence Diagnostic with Hinode/EIS, poster 2.21 at the 12th European Solar Physics Meeting, published electronically
Schmieder, B., Heinzel, P., Schwartz, P., Gunar, S. 2008, Prominence and its Coronal Cavity Observed by Hinode, TRACE and SOHO, poster 2.95 at the 12th European Solar Physics Meeting, published electronically
Schwartz, P., Tziotziou, K., Heinzel, P., Tsiropoula, G. 2008, Contrast of Fine-scale Structures in a Quiet Sun Network Region, poster 2.35 at the 12th European Solar Physics Meeting, published on internet
Švanda, M., Kosovichev, A. G., Zhao, J. 2008a, ApJ, 680, L161
Švanda, M., Klvaňa, M., Sobotka, M. 2008b, 12th European Solar Physics Meeting, Freiburg, Germany, held September, 8-12, 2008. Online at http://espm.kis.uni-freiburg.de/, p.2.10. Extended version in arXiv:0809.4757
Švanda, M., Klvaňa, M., Sobotka, M., Kosovichev, A. G., Duvall, T. L. Jr. 2009, New Astronomy, 14, 429
Tsiropoula, G., Tziotziou, K., Schwartz, P., Heinzel, P. 2008, Multi-wavelength Analysis of a Solar Network Region, in Central European Astrophysical Bulletin, Vol. 32, p. 109-116
Tsiropoula, G., Tziotziou, K., Schwartz, P., Heinzel, P. 2009, A&A, 493, 217
Tziotziou, K., Tsiropoula, G., Heinzel, P. 2008, Influence of Seeing on Cloud Model Parameters Obtained from H? Observations, in Proc. of the conference First Results From Hinode, Eds. S. A. Matthews, J. M. Davis, and L. K. Harra , ASP Conference Series, Vol. 397, 63
Tziotziou, K., Tsiropoula, G., Schwartz, P., Heinzel, P. 2008, Oscillatory Phenomena in a Solar Network Region, poster 2.41 at the 12th European Solar Physics Meeting, published electronically
Zuccarello, F., Romano, P., Fárník, F., Karlický, M., et al. 2009, A&A, 493, 629
Report prepared by Petr Heinzel (PI)
