CATEGORIES
Coimbra Solar Physics Meeting 2015
Ground-based Solar Observations in the Space Instrumentation Era Free Conference is closed
Conference is closed
cspm2015
Affiliation Kiepenheuer Insitute for Solar physics
Coimbra (Portugal)
04.10.2015 - 08.10.2015

Organizing institutions
Main category Natural Sciences (Astrophysics and Astrononmy)
Conference/Workshop objectives

Full-disk spectroheliograms have been routinely taken in Coimbra since 1926 in the Ca II K-line (K1 and K3) and in 1990 regular observations in the Hα line have also started. In 2006, the Astronomical Observatory of the University of Coimbra (Coimbra, Portugal) – Observatório Astronómico da Universidade de Coimbra (OAUC) organized an international solar physics meeting (the first Coimbra Solar Physics Meeting 2006) jointly with a historical session commemorating the life and work of Prof. Francisco Costa Lobo (1864-1945) who installed the spectroheliograph in Coimbra in the 1920s. On June 22, 2013, UNESCO added the University of Coimbra one of the oldest European universities founded in 1290, to its World Heritage List.
Now, we invite again a wide scientific community to join us in 2015, this time for discussing the state-of-art of solar ground-based and space-based observing techniques and related topics. This meeting is included in the celebration of the 150 years of Geophysical Institute of the University of Coimbra. It will take place in the University campus just inside the Coimbra historical down-town and will also include an excursion to the Coimbra Observatory which is located at the city periphery.
The Sun and its activity affect the entire heliosphere, including the Earth. Solar activity includes flares, coronal mass ejections (CMEs), eruptive prominences and filaments, outbursts at various spatial scales, sunspots, and plages. All these phenomena are driven by the magnetic field. Although these phenomena appear at time scales from seconds to months, the long-term variation of the magnetic field during the 11-year solar cycle modulates their frequency and space weather impact. Coronal phenomena are driven by the dynamo-generated fields that show large-scale organization.
Solar magnetic fields can be investigated from ground and space. Ground based observations of solar magnetic fields using polarimetry has a long history, contributing to the understanding of long-term behaviour of the Sun. Spectropolarimetric observations in FUV and EUV lines can only be made from space; they represent virgin territory and they are urgently needed for exploring the magnetic activity of the upper chromosphere and transition region.
This CSPM-2015 scientific meeting will cover various aspects of solar dynamic and magnetic phenomena which are observed over the entire electromagnetic spectrum: white-light, Hα, Ca II, and radio from ground and in a variety of other wavelengths (white light, UV and EUV, and X-rays) from space. Emphasis will also be placed on instrumentation, observing techniques, and solar image processing techniques, as well as theory and modelling through detailed radiative transfer in increasingly realistic MHD models. The long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather, will be in focus. Here, special attention will be devoted to the long-term observations made in Coimbra and also to the results of the SPRING / SOLARNET and SCOSTEP VarSITI studies. In particular, the weak solar activity during the current solar maximum will be discussed. Finally, since this meeting is organised around the 90th anniversary of performing the first spectroheliographic observations in Coimbra, a session will be specially dedicated to new solar instruments (both ground-based and space-borne) that will give access to unexplored solar atmospheric features and dynamic phenomena over the coming years.

Local organizing committee

T. Barata (OGAUC/CITEUC, Coimbra, Portugal)
S. Carvalho (OGAUC/CITEUC, Coimbra, Portugal)
I. Dorotovič (OGAUC/CITEUC, Coimbra; UNINOVA-CA3, Caparica, Portugal; SCO, Hurbanovo, Slovakia)
T. Esperança (OGAUC, Coimbra, Portugal)
J. Fernandes (OGAUC/CITEUC, Coimbra, Portugal) - Chair
A. Garcia (OGAUC, Coimbra, Portugal)
D. Maia (CICGE, University of Porto, Portugal)
A. Morozova (OGAUC/CITEUC, Coimbra, Portugal)
D. Passos (CENTRA - Instituto Superior Técnico, Univ. de Lisboa, Portugal; GRPS, Univ. Montreal, Canada)

Scientific organizing committee (SOC)

J. Aboudarham (OBSPM, Paris-Meudon, France)
F. Clette (ROB, Brussels, Belgium)
I. Dorotovič (OGAUC/CITEUC, Coimbra; UNINOVA-CA3, Caparica, Portugal; SCO, Hurbanovo, Slovakia) - Chair
C. Fischer (KIS, Freiburg, Germany)
L. Fletcher (University of Glasgow, Glasgow, Scotland, United Kingdom)
N. Gopalswamy (NASA-GSFC, Greenbelt, USA)
A. Kučera (AI SAS, Tatranská Lomnica, Slovakia) - Co-chair
D. Maia (CICGE, University of Porto, Portugal)
M. Sobotka (AI ASCR, Ondrejov, Czech Republic)
Y. Suematsu (NAOJ, Tokyo, Japan)
M. Temmer (IGAM, University of Graz, Austria)
J. Trujillo-Bueno (Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain)
G. Tsiropoula (National Observatory of Athens, Athens, Greece)
B. Vršnak (Hvar Observatory, Zagreb, Croatia)

Sessions
• Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)
• Solar image management, spectro-polarimetric and processing techniques (overview of image management and processing techniques including tutorials)
• Theory and modeling - comparison to observations (constraints from observations)
• Long-term variations of the Sun (long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather)
• Facilities for ground-based and space solar observations (existing and new facilities)
Programme
Invited speakers

LIST OF INVITED SPEAKERS

• Session 1:
• L. van Driel-Gesztelyi (Mullard Space Science Laboratory, University College London, UK; LESIA, Paris Observatory, Paris-Meudon, France)
• K. Tziotziou (Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Penteli, Greece)
• A. Pevtsov (National Solar Observatory/Sacramento Peak, Sunspot, USA)
• L. Bellot Rubio (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain)
• C. Denker (Leibniz Institute for Astrophysics (AIP), Potsdam, Germany)
• A. Lagg (Max Planck Institute for Solar System Research, Göttingen, Germany)

• Session 2:
• M. Löfdahl (Institute for Solar Physics, Stockholm University, Stockholm, Sweden)
• J. Ireland (ADNET Systems, Inc. / NASA-GSFC, Greenbelt, USA)
• M. van Noort (Max Planck Institute for Solar System Research, Göttingen, Germany)

• Session 3:
• T. Török (Predictive Science Inc., San Diego, USA)
• J. Leenaarts (Institute for Solar Physics, Stockholm University, Stockholm, Sweden)
• R. Erdélyi (Solar Physics & Space Plasma Reserach Centre (SP2RC), School of Mathematics & Statistics, University of Sheffield, UK)

• Session 4:
• A. Veronig (Kanzelhöhe Observatory/Institute of Physics, University of Graz, Austria)
• S. Solanki (Max Planck Institute for Solar System Research, Göttingen, Germany)
• I. Usoskin (Sodankylä Geophysical Observatory, University of Oulu, Finland)
• L. Bertello (National Solar Observatory, USA)

• Session 5:
• W. Schmidt (Kiepenheuer Institute for Solar Physics, Freiburg, Germany)
• M. Collados (Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain)
• D. Müller (ESA-ESTEC, Noordwijk, The Netherlands)
• Y. Suematsu (National Astronomical Observatory of Japan, Tokyo, Japan)
• Y. Deng (National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China)

Important dates

15 November 2014  - First Announcement, web-site opens
- Registration, hotel reservation, and abstract submission opens
30 April 2015       - Closing date for abstract submission I. (for those who are going to apply for financial support)
- Closing date for financial support applications
20 June 2015    - Closing date for abstract submission II. (for those who do not apply for financial support)
- Closing date for Thomas Metcalf SPD Travel Award applications
- Information on financial supports
5 July 2015       - Information on accepted abstracts
- Second Announcement (Programme Finalised)
15 July 2015        - Closing date for early bird registration
15 September 2015   - Closing date for late registration and for hotel reservation
- Final Announcement
4 October 2015    - Arrival, registration
5 October 2015    - Meeting starts
9 October 2015    - Meeting ends
30 November 2015    - Submission deadline for proceedings manuscripts

Registration and payment information

The registration fee is 285 € per participant for early bird registration (till 15 July, 2015)
and 350 € per participant for late registration (till 15 September, 2015).
The registration fee for onsite registration and/or payment is also 350 €.

Conference venue Coimbra (Portugal)
Hotel information

The LOC have a special agreement with the local professional congress organiser Abreu PCO to provide registration service, hotel reservation and social events arrangements. Special hotel rates have been negotiated for the participants of the meeting in several hotels.

Helena Desidério

Abreu - PCO
Av. 25 de Abril 2 - Edifício Abreu
2799-556 Linda-a-Velha - Portugal
Congress Department
Fax: + 351 21 415 63 83
E-mail: helena.desiderio@abreu.pt

Travel information

Coimbra is an old university town situated in the central region of Portugal, between Lisbon (200 km) and Porto (100 km) and about 35 km from the Atlantic coast at Figueira da Foz. It is easily reached from Lisbon and Porto, which both have international airports, by train (up to 2h from Lisbon and 1h15 from Porto) or by bus. The A1 motorway from Lisbon to Porto passes close to Coimbra; there are also good road connections with Spain through Salamanca.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

1321 views
26.10.2015
Co-author:
Caption:
Slipping reconnection model

Session: Long-term variations of the Sun (long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather)

838 views
08.10.2015
Co-author:
Frank Hill[2], Michael Thompson[3], Sanjay Gusain[1,2]
Abstract:
SPRING is a project to develop a geographically distributed network of instrumentation to obtain synoptic solar observations. Building on the demonstrated success of networks to provide nearly-continuous long-term data for helioseismology, SPRING will provide data for a wide range of solar research areas. Scientific objectives include internal solar dynamics and structure; wave transport in the solar atmosphere; the evolution of the magnetic field over the activity cycle; irradiance fluctuations; and space weather origins. Anticipated data products include simultaneous full-disk multi-wavelength Doppler and vector magnetic field images; filtergrams in H-Alpha, CaK, and white light; and PSPT-type irradiance support. The data will be obtained with a duty cycle of around 90% and at a cadence no slower than one minute. The current concept is a multi-instrument platform installed in at least six locations, and which will also provide context information for large-aperture solar telescopes such as EST and the DKIST. There is wide support for the idea within the EU and the US solar research communities. The project is in the early planning stages, and we are open to and looking for participants in the science and instrument definition.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

738 views
09.10.2015
Co-author:
Abstract:
The temperature in the solar atmosphere ranges over three orders of magnitude from the photosphere to the corona, which extends up to four during periods of transient activity. Consequently, the wavelengths we can observe certain details of large-scale transients, i.e. coronal mass ejections (CMEs) and related flares range over from radio, through optical to X-rays. Non-thermal effects further broaden the range. Large transients show signatures at most wavelengths, which in turn provide highly complementary information, necessary for a synthesis. To form an increasingly complete observational picture of CMEs, we need broad and ever-broadening multi-wavelength, multi-instrument observational coverage both from the ground and space. As the formation of CMEs involve long time-scales and only probabilistic predictions are available for their onset time, we need long synoptic sequences. Once the onset is imminent, the sequence of events accelerates and there is a need for high-cadence observations. Even in the low corona, CMEs couple small scales (e.g. flare in their source active region) and large scales (e.g. the extent of a Moreton or global EUV wave). Therefore we need high spatial resolution observations focused on the small-scale, but should we neglect its large-scale signatures and its interaction with surrounding magnetic fields, we will never fully understand a CME. As CMEs travel from the solar corona through the interplanetary space, they need to be tracked by coronagraphs, radio instruments adapted to the low-frequency plasma emission, and their magnetic fields and plasma measured in situ. I will give an overview of multi-wavelength CME signatures and emphasize the importance of magnetic field measurements in particular, necessary to make progress in understanding their formation.

Session: Theory and modeling - comparison to observations (constraints from observations)

952 views
09.10.2015
Co-author:
Abstract:
The unusually large NOAA active region (AR) 2192, observed in October and November 2014, was outstanding in its productivity of major flares (GOES class M5 and larger). However, none of the X-flares was associated to a coronal mass ejection. The AR showed a predominantly north-south oriented magnetic system of arcade fields, which served as a strong, also lateral, confinement for the flares at the core of the active region. The large initial separation of the flare ribbons, together with an almost absent growth in ribbon separation suggests a confined reconnection site high up in the corona. Based on a detailed analysis of the confined X1.6 flare of Oct 22, we show how exceptional the flaring of this AR was. We find evidence for repeated energy release, presumably due to magnetic reconnection in a narrow flaring volume, closely associated to the location of hard X-ray sources. We demonstrate that a considerable portion of the magnetic energy released during the X-flare was consumed by the non-thermal flare energy.

Session: Long-term variations of the Sun (long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather)

1030 views
12.10.2015
Co-author:
Laure Lef\`evre, Edward W. Cliver, Leif Svalgaard
Abstract:
In 2015, a new entirely recalibrated version of the sunspot number and group number series has been released. Important changes, by up to 40\%, have been applied to the original historical series, leading to a new picture of the secular evolution of solar activity, without significant upward trend between the $17^{th}$ and the $20^{th}$ century. We first describe the main changes and implications of this very first revision of the sunspot number series since its creation, more than 165 years ago. We also discuss the long-term non-linear relation between the sunspot number and the group number, as it is now free from artifacts. Both series are now largely reconciled, but do not fully overlap, clearly reflecting different properties of the solar cycle. Together with this major step, several important changes were simultaneously adopted regarding past conventions. We will explain the various modifications and their motivations, in order to help users making the proper adaptations. In particular, A.Wolfer was chosen as the new reference, in place of R. Wolf, thus dropping the fixed 0.6 Z\"urich factor. For the group numbers, given the time variability of the average number of spots per group, we don't apply anymore a constant scaling factor to match the average scale of the sunspot number, in contrast with the previous series by Hoyt and Schatten (1998). Finally, we present the new data sets and data formats adopted for this revised series and for the future production of the sunspot number. The new SILSO Web portal will provide access both to current and past versions of the series, allowing to keep track of future revisions and thus giving more flexibility to follow future progresses in sunspot science. Finally, we conclude on the redefinition of the base method used to routinely produce the sunspot number from all current and future observations of the SILSO worldwide network. New tools and statistical approaches derived directly from our global recalibration work will soon be ported to our operational software, improving the quality control and the long-term stability of the sunspot number series. This will complete the necessary modernization of our only direct long-term record of solar activity.

Session: Long-term variations of the Sun (long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather)

943 views
09.10.2015
Co-author:
Abstract:
In this talk, I review the availability and use of ground-based observations for the study of the solar sources of space weather. High-cadence full-disk imaging in the H-alpha spectral line provides us with a valuable means to identify solar flares, erupting filaments which may be associated with Earth-directed coronal mass ejections and Moreton waves indicating shock waves propagating through the solar corona. We present the automatic real-time detection of solar flares and filaments, which was developed and implemented at the Kanzelhöhe Observatory H-alpha observing system (in the frame work of ESA’s SSA space weather segment, http:// http://swe.ssa.esa.int). Specific problems related to ground-based observations and the potential of observing networks for space weather research will be discussed

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

1117 views
12.10.2015
Co-author:
P. Schwartz^1, P. Heinzel^2, S. Jejcic^3, J. Rybak^1, P. Kotrc^2, F. Farnik^2, Yu. A. Kupryakov^{2,4}, E. E. DeLuca^5, L. Golub^5, P.R. Jibben^5, U. Anzer^6, A.G. Tlatov^7, S.A. Guseva^7; 1 Astronomical Institute of Slovak Academy of Sciences, 05960 Tatranska Lomnica, Slovak Republic; 2 Astronomical Institute, Czech Academy of Sciences, 25165 Ondrejov, Czech Republic; 3 University of Ljubljana, Faculty of Mathematics and Physics, 1000 Ljubljana, Slovenia,; 4 Sternberg Astronomical Institute, 119899 Moscow, Russia; 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MA 02138 Cambridge, USA; 6 Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild-Strasse 1, 85740 Garching, Germany; 7 Kislovodsk Mountain Astronomical Station of the Pulkovo observatory, Kislovodsk 357700, Russia
Abstract:
Total masses of six quiescent prominences observed from April through June 2011 were estimated using multi-spectral observations (in EUV, X-rays, H alpha,and Ca ii H) and method based on work of Heinzel et al. (2008). The method uses the fact that intensity of the EUV solar corona at wavelengths below 912 Å is reduced at a prominence by the absorption in resonance continua (photoionisation) of hydrogen and possibly by helium and subsequently an amount of absorbed radiation is proportional to the column density of hydrogen and helium plasma. Moreover, the deficit of the coronal emissivity in volume occupied by the cool prominence plasma also contributes to the intensity decrease. The observations in X-rays which are not absorbed by the prominence plasma, allow us to separate these two mechanisms from each other. The X-ray observations of XRT onboard the Hinode satellite made with the Al-mesh focal filter were used because the X-ray coronal radiation formed in plasma of temperatures of the order of 10^6 K was registered and EUV spectral lines occurring in the 193, 211 and 335 A channels of the Atmospheric Imaging Assembly of the Solar Dynamics Observatory satellite are also formed at such temperatures. Unfortunately, the Al-mesh filter has a secondary peak of the transmittance at around 171 A what causes a contribution from the EUV corona to the measured data of up to 10 % in the quiet corona. Thus, absorption in prominence plasma influences XRT X-ray data when using the Al-mesh filter. On the other hand, other X-ray XRT filters are more sensitive to plasma of much higher temperatures (log T of the order of 7), thus observations using these filters cannot be used together with the AIA observations in the method for mass estimations. This problem could be solved using observations in the green coronal line instead of X-rays. Absorption of the green coronal line by a prominence plasma is negligible and this line is formed at temperatures of the order of 10^6 K. We compare values of the total mass of the prominence observed on 20 October 2012 on SE limb estimated when using XRT X-ray observations and observations in the green coronal line obtained at Kislovodsk Mountain Astronomical Station of the Pulkovo observatory (Russia).

Session: Solar image management, spectro-polarimetric and processing techniques (overview of image management and processing techniques including tutorials)

706 views
19.10.2015
Co-author:
Abstract:
Solar images from high-resolution, ground-based telescopes are corrected for the blurring effects of atmospheric turbulence by adaptive optics and image restoration. Two classes of image restoration methods are regularly used today, those based on multi-frame blind deconvolution and those based on speckle interferometry. In a recently started project, we will compare and evaluate such methods for use with spectropolarimetric data from SST/CRISP. During this presentation, I will describe the two methods and our results so far.

Session: Theory and modeling - comparison to observations (constraints from observations)

679 views
19.10.2015
Co-author:
V.S. Titov, Z. Mikić, C. Downs, R. Lionello, J.A. Linker, J.E. Leake, M.G. Linton
Abstract:
The numerical modeling of the solar corona and of its dynamical phenomena has experienced significant progress in recent years. Present magnetohydrodynamic (MHD) simulations can be run on large spherical grids, include a realistic description of the energy transfer (thermodynamics) in the corona, and are capable of incorporating photospheric measurements as boundary condition for the magnetic field. These capabilities now allow us to model the large-scale magnetic field and plasma distribution of the corona, as well as transient eruptive phenomena such as jets and coronal mass ejections (CMEs) with unprecedented realism. In this talk, I will review some of these simulations and briefly discuss the next steps that lie ahead.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

770 views
20.10.2015
Co-author:
Abstract:
Synoptic observations are indispensable in studies of long-term effects pertinent to variation in solar radiative output, space weather and space climate, as well as for understanding the physics of global processes taking place on our nearest star. Synoptic data also allow putting the Sun in the context of stellar evolution. Historically, the main-stay of such observations has been ground-based, although the improving longevity of space-borne instruments puts some space missions into the category of synoptic facilities. Space- and ground-based (synoptic) observations are complementary to each other; neither is inferior or superior to the other. Ground-based facilities can have a long-term (50 years+) operations horizon, and in comparison with their space-based counterparts, they are less expensive to operate and have fewer restrictions on international collaboration and data access. The instruments can be serviced, upgraded, and cross-calibrated to ensure the continuity and uniformity of long-term data series. New measurements could be added in response to changes in understanding the solar phenomena. Some drawbacks such as day-night cycle and the variable atmospheric seeing can be mitigated e.g., by creating the global networks and by employing the adaptive optics. Furthermore, the ground-based synoptic observations can serve as a backbone and a back-up to space-based observations. In my talk I will review some existing ground-based synoptic facilities, describe plans for future networks, and outline the current efforts in strengthening the international collaboration in synoptic solar observations from the ground.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

649 views
21.10.2015
Co-author:
D. Utz, J. Rybák
Abstract:
We studied spectroscopic signatures of potential means of energy transport into the chromosphere by investigating temporal variations of the width, the intensity and the Dopplershift of the Hα spectral line profile observed by the tunable Lyot filter installed on the Dutch Open Telescope. Furthermore, we studied co-spatial chromospheric and photospheric structures with a likelihood of being causally connected to the variations of these spectroscopic signatures. We found oscillations in the intensity and Doppler velocities, while the width of the Hα spectral line profile produced no discernible periodicity. Moreover, the amplitude of the intensity is lagging behind the Doppler velocities. We interpret our findings as signatures of magneto-acoustic wave propagation. The investigation of the likely source of the observed oscillations directed our attention to bright chromospheric mottles. Subsequently, we studied the possible relation of their appearance wit h a co-spatial long-living and dynamically evolving group of G-band bright points (GBPs). According to our findings we propose a causal relation between the dynamical evolution of the group of GBPs and the appearance of bright mottles in the region above them.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

1003 views
22.10.2015
Co-author:
SOLAR-C WG
Abstract:
Solar-C is a Japan-led international solar mission designed to investigate the magnetic activities of the Sun, focusing on the study in heating and dynamical phenomena of the chromosphere and corona, and also to develop an algorithm for predicting short and long term solar evolution.It has long been known that the interplay between magnetic fields and plasmas is at the heart of most solar phenomena, but the details of this interplay are in many cases clouded in ambiguity and uncertainty. To dramatically improve the situation, SOLAR-C will carry three dedicated instruments; the Solar UV-Vis-IR Telescope (SUVIT), the EUV Spectroscopic Telescope (EUVST) and the High Resolution Coronal Imager (HCI), to jointly observe the entire visible solar atmosphere with essentially the same high spatial resolution (0.1-0.3 arcsec), performing high resolution spectroscopic measurements over all atmospheric regions and spectro-polarimetric measurements from the photosphere through the upper chromosphere. In addition, Solar-C will contribute to our understanding on the influence of the Sun-Earth environments with synergetic wide-field observations from ground-based and other space missions. I will present some leading science objectives and the mission concept, including the current status of SOLAR-C.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

749 views
26.10.2015
Co-author:
J. Dudík, C. Denker, H. Balthasar, J. Jurčák, W. Liu, and the GREGOR Team
Abstract:
A small flare ribbon above a sunspot umbra in active region 12205 was observed on November 7, 2014, at 12:00 UT in the blue imaging channel of the 1.5-m GREGOR telescope, using a 1 A Ca II H interference filter. Context observations from SDO/AIA, Hinode/SOT, and IRIS show that the ribbon is a part of a larger one that extends through the neighboring positive polarities and also participates in several other flares within the active region. A 140 second long time series of Ca II H images was reconstructed by means of the Multi-Frame Blind Deconvolution method, giving the respective spatial and temporal resolutions of 0.1 arcsec and 1 s. Light curves and horizontal velocities of small-scale bright knots in the observed flare ribbon were measured. Some knots are stationary but three move along the ribbon with speeds of 7 - 11 km/s. Two of them move in the opposite direction and exhibit highly correlated intensity changes, providing evidence for the presence of slipping reconnection.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

953 views
25.09.2015
Co-author:
M. Rybansky (1), M. Sobotka (2), M. Lorenc (1), M. Barandas (3), J. M. Fonseca (3); 1 - Slovak Central Observatory, Komárňanská 134, SK-94701 Hurbanovo, Slovak Republic; 2 - Astronomical Institute, ASCR, Fricova 298, 251 65 Ondřejov, Czech Republic; 3 - CTS-UNINOVA/CA3, Campus FCT/UNL, Caparica, Portugal
Abstract:
We describe conditions of pore formation in relation to the configuration and intensity of magnetic field. We used observations of the SDO/HMI instrument, which observes the photosphere in continuum and simultaneously the magnetic field with a spatial resolution of better than $1^{\prime \prime}$ and a temporal resolution of 45 s. We analyze a time-sequence of evolution of area and brightness of pores, their statistics, and in parallel a time-sequence of the line-of-sight magnetic field intensity and its correlation with the area and brightness. Sunspot observations from the Hurbanovo Observatory are used for selection of a suitable area on the solar disc. A pore (small sunspot) observed near the central meridian at the Observatory in Hurbanovo on October 10 and 11, 2013 was selected for analysis. We chose from each SDO image only area with a diameter of $1.05^{\circ}$ ($35^{\prime \prime}$ as seen from the Earth). Points of the area were transformed into rectangular coordinates ($\Delta$l, b) and for alignment of individual images we found from the movement of a pore the synodical rotational speed: $\omega$ = $14.35^{\circ}$/24 hours, which is by $1^{\circ}$ more than a tabular value. We traced the selected area from 22:01:30 UT (October 10, 2013) to 20:01:30 UT (October 11, 2013) in 83 images with a temporal resolution of 15 minutes. Evolution of the area was analyzed using an animation and quantitative results are derived from data files. At least 6 pores occured in the area during the reported period. Pores are visible if a ratio p (p = intensity in the pore/background intensity) decreases below 0.85. The background noise is at a level of 5% (granulation). Magnetic induction is in the same time at around 600 Gauss (60 mT). The maximum diameter of a pore is about $5^{\prime \prime}$ (1 pixel in the center of the disk is $0.5^{\prime \prime}$), the minimum value of p = 0.49; when B = 1200 Gauss. The course of evolution is presented in a tabular form. Aim of the analysis is demonstrated also using selected images from SDO in cooperation with CTS-UNINOVA/CA3 (Caparica, Portugal).

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

809 views
06.10.2015
Co-author:
N. Bello González, R. Rezaei
Abstract:
We have calibrated and aligned a co-spatial and co-temporal 3 hour quiet sun time series taken with the Hinode and IRIS satellites. Hinode SOT observed full Stokes profiles of the Fe I 630 line pairs with the Spectro-polarimeter (SP) scanning a 8.7 arcsec region with a cadence of about 70 seconds. The Broadband Filter Imager (BFI) observed in Ca II H with a cadence of 31 s which was complemented by magnetograms and dopplergrams constructed from Na D I 589,6 nm measurements observed by the Narrowband Filter Imager (NFI). The IRIS satellite recorded slit jaw images centered at 2832 Å (112 s cadence), 1390 Å (23 s) and with a cadence of 19 s at 2796 Å. The spectrograph recorded spectra in several passbands including the Mg II k and h lines performing a 2 step raster with a 9.5 s step cadence. We study magnetic elements seen in SP and NFI data undergoing a magnetic field intensification process accompanied by the development of bright points in the Ca II H images which we identify as convective collapse events. In addition we study pairs of magnetic elements involved in flux cancellation. The magnetic elements pass the IRIS slit at different stages of these processes. The IRIS Magnesium lines spectra are analyzed to investigate the response of the chromosphere to the magnetic events in the photosphere below. We present the temporal evolution of the atmospheric parameters from the photosphere to the transition region during these occurrences and compare the results to convective collapse and flux cancellation models.

Session: Long-term variations of the Sun (long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather)

961 views
08.10.2015
Co-author:
C. Renié
Abstract:
From 1919 to 2002, Paris-Meudon Observatory published synoptic maps of the Solar activity. Together with maps, tables were provided, containing some information concerning at least filaments. The board of Paris Observatory funded a data capture program concerning the 680 000 basic informations available in those tables. On the other hand, in the frame of the FP7 European project HELIO, a Heliophysics Feature Catalogue (HFC) has been developed, which contains also filaments data from 1996 up to now. We now pool all these data in order to give access to a filaments database for nearly a century of observations. This allows to make statistical studies of those Solar features, and try to correlate them with other information such as sunspot number, ... . We present here the first results of such studies, showing long-term global behavior of filaments.

Session: Solar image management, spectro-polarimetric and processing techniques (overview of image management and processing techniques including tutorials)

924 views
12.10.2015
Co-author:
S. Vargas Domínguez, L.A. Balmaceda, I. Cabello, V. Domingo
Abstract:
In this work we follow a series of papers on high-resolution solar observations (Balmaceda et al. 2009, Balmaceda et al. 2010, Vargas Dominguez et al. 2011, Palacios et al. 2012, Vargas Domínguez et al 2015, Cabello et al., in preparation), utilizing several long multi-wavelength data series. These were acquired from both ground-based (SST) and space-borne (Hinode), thus obtaining high-cadence and high resolution data, including SOT-SP data, in a joint campaign of the Hinode Operation Program 14, in Sept 2007. Diffraction-limited SST data, taken in G-band and G-cont, were restored by MFBD, whilst Hinode obtained multispectral data from SOT-FG in CN, Mg II, Ca II and also SP in Fe I lines. In these series we have thoroughly studied vortex flows and their statistical occurrences, horizontal velocities by means of local correlation tracking (LCT), divergence and vorticity; but we also have studied bright point statistics and magnetic field intensification, clearly highlighting the importance of the smallest-scale magnetic element observations.

Session: Theory and modeling - comparison to observations (constraints from observations)

1133 views
09.10.2015
Co-author:
P. Schwartz, H. Balthasar, C. Kuckein, J. Koza, P. Gömöry, J. Rybák, A. Kučera, P. Heinzel
Abstract:
An active-region filament in the active region NOAA 12159 (at solar disk coordinates [x,y] = [225,-440] arcsec) was observed with the Vacuum Tower Telescope at Tenerife on 11 September 2014. Full-Stokes spectropolarimetric observations of the HeI IR triplet at a wavelength around 10830 Å and of the SiI 10827 Å line were acquired using the VTT Echelle spectrograph together with the Tenerife Infrared Polarimeter (TIP I). Additional simultaneous spectroscopic observations in the CaII 8542 Å line were also obtained with the Echelle spectrograph. With the TESOS Fabry-Pérot interferometer, the filament was observed in Ha in intensity mode with a field-of-view of 25 x 25 arcsec (136 wavelength points within the range 6561 – 6564 Å). The filament shows a structure typical for an active filament composed of thin and long fluxtubes with plasma flowing along the magnetic field lines inside these fluxtubes. Thus, for diagnostics of the filament plasma, observed Ha profiles are simulated using a simple isothermal and isobaric two-dimensional non-LTE model with two finite dimensions -- vertical and across the fluxtube. The velocity of the plasma flows is also taken into account in the model because it can cause a Doppler brightening in the observed profiles. Assuming the flows are parallel to the magnetic field lines in the fluxtube, the LOS component is then projected onto a velocity vector according to the direction of the vector magnetic field that we were trying to obtain from inversions using the HAZEL inversion code (Asensio Ramos, 2008).

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

816 views
19.10.2015
Co-author:
Francisco C. R. Fernandes
Abstract:
We report the analysis of the observational parameters of the two Radio Noise Storms (RNS): one day in the occurrence of the solar flares in X-rays and one day without the presence of the flare. The spectral information about the chains of type I in the events obtained of the network e-CALLISTO (Compact Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory) revealed in 07/05/2011 (day without flare) bandwidth in the range 5.7 {-}{-} 91 MHz, the duration varied from 7 {-}{-} 361 seconds, and the frequency drift-rate was in the range -5.2 {-}{-} +2.5 MHzs$^{-1}$. Day whit flare (01/08/2011) presented bandwidth in the range 4.7 {-}{-} 60 MHz, duration between 6 and 214 seconds and frequency drift-rate varied from -6 to +1.8 MHzs$^{-1}$.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

832 views
19.10.2015
Co-author:
Mateja Dumbović, Bojan Vršnak, Roman Brajša
Abstract:
The double solar telescope at the Hvar Observatory consists of two Carl Zeiss refractors, attached as one unit on a German parallax mounting. The photosphere telescope has an objective diameter of 217 mm and the chromosphere telescope has a diameter of 130 mm. It provides a valuable instrument to study rapid changes of chromospheric and photospheric features. Using a field of view of about 11 and 7 arcmin, it aims to produce high-resolution and high-cadence imaging of active regions on the Sun. Modern Pulnix TM-4200GE 12-bit 4 megapixel CCD cameras allow to obtain time series with a cadence up to 30 images per minute. High-cadence chromosphere ground-based observations are an important tool to identify and study solar flares, filaments and other solar phenomena that are associated with coronal mass ejections and their propagation to the Earth. Hence these observations can be also used to improve space weather forecasts. This work has been supported by the ESF project PoKRet and the Croatian Science Foundation project SOLSTEL.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

1061 views
20.10.2015
Co-author:
Abalde, J. R., Tardelli, A., de Abreu, A. J.
Abstract:
Studies presented on the relation Sun-Earth system are of great importance currently. Ionospheric irregularities in the F-region, caused by geomagnetic storms have meanings and adverse effects on the Earth. The recent advancement in technology techniques for monitoring space weather has allowed major contributions to this aspect. The main research of this study was to determine whether there was some geomagnetic storm that interfere with the generation, propagation and durability of plasma bubbles that occurred over a period of solar minimum in two cities in the Brazilian sector, São José dos Campos - SP (23.21°S, 45.86°W; dip latitude 17.6°S), designated SJC, low-latitude region and near to south crest ionospheric equatorial anomaly and Palmas - TO, called PAL (10.28°S, 48.33°W; dip latitude 6.7°S), near to the magnetic equator, located in the geographical South, tropical region and the hemisphere opposite to the magnetic equator. This study was conducted with data analysis of five years (2006-2010) of SJC and four years (2007-2010) of PAL, considering the 24th solar cycle, using all-sky imaging photometer operating with interference filters in OI 630.0 nm emission resulting from dissociative recombination process that occurs at an altitude of ~ 250-300 km (F-region).

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

1073 views
20.10.2015
Co-author:
Paulo Garcia
Abstract:
Wave front sensing for solar telescopes is commonly implemented with Shack-Hartmann sensors. The Shack-Hartmann lenslet sub-aperture solar image shifts/slopes are usually estimated with correlation algorithms. The sub-pixel precision image shifts are computed by applying a peak-finding algorithm to the correlation peak. Usually, the measured image displacements consist of systematic errors due to pixel locking effects, because correlation matching is limited only to an integer pixel grid. The amplitude of the systematic error depends on the combination of the correlation algorithm chosen to compute the correlation peak with the type of peak-finding algorithm chosen. To study the systematic errors in detail, solar sub-aperture synthetic images are constructed by using a Swedis Solar Telescope solar granulation image. The performance of different cross-correlation peak finding algorithms is investigated. The algorithms are: parabola; quadratic polynomial; threshold center of gravity; Gaussian and Pyramid. It is found that pyramid fit is the most robust to pixel locking effects. The RMS error analysis study reveals that threshold centre of gravity behaves better in low SNR although systematic errors in the measurement are large. It is found that no peak finding model is good enough in attenuating both systematic errors and RMS error. A new method is proposed to overcome the above limitations. It works in two steps. In the first, the cross-correlation is executed at the original image spatial resolution grid (1 pixel). In the second, the cross-correlation is performed with a sub-pixel level grid and by confining the field of view to 4 x 4 pixels centered at the first step delivered initial position. The generation of these sub-pixel grid based search windows from the spatially discrete target image is achieved with bi-linear interpolation. This method is called as cross-correlation executed at continuous grid (CCC). This technique was previously reported in electronic speckle photography. This technique is applied to wave front sensing. The combination of coarse level grid search executed in large field followed by quasi-continuous grid search executed in a small field enables one to achieve high accuracy wave front estimation by reducing the systematic errors with a low computational cost. The results show that the proposed method outperforms all the approaches in the first study. It improves the wave front estimation accuracy to a factor of 5 in terms of both systematic error and RMS error (75% systematic error reduction, for 0.2 pixel sub-sampling grid), at the expense of twice the computational cost. The CCC method is strongly recommended for wave front sensing in solar telescopes, particularly in open loop adaptive optics, for measuring large the dynamic shifts.

Session: Facilities for ground-based and space solar observations (existing and new facilities)

773 views
21.10.2015
Co-author:
K. Shibata, K. Ichimoto, S. Nagata (Kwasan and Hida Observatories, Kyoto University, Japan) I. Dorotovič, E. Shahamatnia, R.A. Ribeiro, J.M. Fonseca (CTS-UNINOVA, FCT/UNL, Caparica, Portugal)
Abstract:
For the realization of the Solar-C satellite, discussions about scientific themes and preliminary observations are internationally carried out now. At Hida Observatory of Kyoto University, we will play the following roles toward the Solar-C era by utilizing the Domeless Solar Telescope (DST) and the international solar chromospheric full-disk observation network (CHAIN project) that includes the Solar Magnetic Activity Research Telescope (SMART) with international collaborations, for example, such as the development of image-analysis software by UNINOVA (Portugal) and so on. 1) Roles before the Solar-C launch: By using DST's focal plane and high-dispersion and wide-wavelength spectroscope, Hida Observatory will play a role as the place of the development of new detectors and focal plane instruments. On the other hand, we will reveal unclear points in the chromospheric physics and in methods of deriving physical quantities of chromosphere, by carrying out spectrum observations and polarization measurements in various chromospheric absorption lines. 2) Roles after the Solar-C launch: Promotion of cooperative observations with Solar-C, mainly by observations with the DST. Our Hida Observatory will perform complimentary observations with satellite's high-spatial-resolution observations that are limited in the spatial FOV and continuous observable time due to the data capacity and lifetime of the satellite, or satellite's spectroscopic observations that are limited in the amount of information along the wavelength direction. Moreover, we will expand and apply new knowledge provided by Solar-C to the whole of the sun, through our international full-disk solar monitoring network observation (CHAIN project). It will mediate between the Solar-C and studies of variations of space weather and space climate. 3) Regular roles: Our observatory continues to provide the place of educational-observation training for students and young researchers where they can gain experiences that they operate instruments by their own hands while watching the Sun in real time. Moreover, we provide the place that can enforce not only scientific advanced themes, but also other themes that are hard to be accepted in the case of satellites or hard to be carried out by satellites physically, for example, experimental themes, classical scientific themes, themes that need long duration or large data capacity, and educational themes etc.

Session: Theory and modeling - comparison to observations (constraints from observations)

1235 views
23.10.2015
Co-author:
T. Zic, J. Calogovic, M. Dumbovic
Abstract:
We present a new space weather online forecast-tool for predicting the arrival of Interplanetary Coronal Mass Ejections (ICMEs). The forecast-tool is based on the “Drag-Based Model” (DBM), developed in the frame of the European Commission FP7 Project SOTERIA (SOlar-TERrestrial Investigations and Archives) and advanced within FP7 Project COMESEP (Coronal Mass Ejections and Solar Energetic Particles) and the Croatian Scientific Foundation Project SOLSTEL (Solar and Stellar Variability). The DBM is based on a hypothesis that the driving Lorentz force that launches CME ceases in the upper corona, and that beyond certain distance the dynamics becomes governed solely by the interaction of the ICME and the ambient solar wind. This assumption is founded on the fact that in the interplanetary space fast ICMEs decelerate, whereas slow ones accelerate, showing a tendency to adjust their velocity with the ambient solar wind. In particular, we consider the option where the drag acceleration has the quadratic dependence on the ICME relative speed, which is expected in the collisionless environment, where the drag is caused primarily by emission of MHD waves. This is the simplest version of DBM, where the equation of motion can be solved analytically, providing explicit solutions for the Sun-Earth ICME transit time and the impact speed. DBM offers easy handling and straightforward application in the real-time space-weather forecasting. DBM results are compared with remotely-measured interplanetary kinematics of several ICMEs, whereas forecasting abilities are validated on the statistical basis by employing in situ measurements. Finally, the advantages and drawbacks of DBM are summarized.

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

1000 views
29.10.2015
Co-author:
The Solar Observatory of NAOJ
Abstract:
The National Astronomical Observatory of Japan has a history of about 100 years of regular synoptic solar observations. It started with Ca K spectroheliographic and white-light imaging observations, and shortly afterward, sunspot count was started. Current imaging observations are being carried out in the Ha line, the Ca K line, the green continuum, and the G-band. In addition, the NAOJ has a history of more than 30 years of magnetic field measurements, and now we are conducting full-Sun spectropolarimetry observations in the wavelengths of He I 10830/Si I 10827 and Fe I 15648. These observational results contribute not only to the monitoring of solar active phenomena from the viewpoint of the space weather, but also to the study of the long-term variability of the solar activity, thanks to the long history. Most of historical photographic (plates and films) and hand-drawn data have been digitized and are now open at our web site as well as recently obtained data. Here we introduce our data to promote the collaboration in the long-term solar activity study. Our data are open at our website: visit http://solarwww.mtk.nao.ac.jp/en/solarobs.html, and go to the database page.

Session: Long-term variations of the Sun (long-term (cyclic) evolution of solar magnetism and its consequence for the solar atmosphere, eruptive phenomena, solar irradiation variations, and space weather)

1147 views
05.11.2015
Co-author:
Abstract:
There are many parameters representing the conditions of space environments. Those are modulated in general by Solar Cycle (SC) defined by sunspot number temporal variation. However, all parameters do not have same cyclic features. Thus, we compare the temporal variations of solar, interplanetary, geomagnetic (SIG) parameters with that of open solar magnetic flux from 1976 to 2014 (from Solar Cycle 21 to the increasing phase of Cycle 24) in order to identify the possible relationships. We investigate which component of solar magnetic multipoles best correlates with the SIG parameters. As results, the dynamic pressure of the solar wind is strongly correlated with the solar magnetic dipole flux, which varies in anti-phase with SC. Other solar activity indices such as the sunspot number, total solar irradiance, 10.7cm radio flux, and solar flare occurrence and highly correlated with quadrupole component. The geomagnetic activity represented by Ap index is correlated with higher order multipole components, which show relatively a lagged time variation with SC. Given these results, we suggest that the continuous observation of solar photospheric field and calculating the multipole components of the open solar magnetic field at the source surface may complement forecasting the geomagnetic activity intensity long term trend

Session: Observations of the Sun (quiet and active Sun, magnetic fields, high-resolution (polarimetric) observations and transient phenomena from the photosphere to the chromosphere and corona)

964 views