SCIENTIFIC PROGRAMME
Conference Programme (pdf file)
Invited Speakers
Thomas Ayres
Sarbani Basu
Svetlana Berdyugina
Maria Bergemann
Matt Browning
Guy Davis
Sebastien Deheuvels
Louise Harra
Laurene Jouve
Lucia Kleint
Zarzalt Magic
Stéphane Mathis
Ian Roxburgh
Ariane Schad
Alina Donea
Sunday - August 30,2015 __
17:00 - 20:00 Lobby Registration
18:30 Lobby City Tour
19:30 Lobby Self-paid dinner in a near-by restaurant
Monday - August 31, 2015 _____________________________________
08:00 Foyer Registration Desk Opens
08:30 Lobby Welcome Coffee
09:00-12:30 Room "Colmar"
Splinter I: Comparing and Validating Meridional Flow Derivations in the Solar Convection Zone
09:25-12:30 Conference Room "Basel"
Splinter II: Waves inside Stars: Theory, Simulations, Observational Signatures, and Lab Experiments
10:30 - 11:00 Coffee Break & Posters
12:30 - 14:00 Lunch at Restaurant La Rotonde
Session I: Solar and Stellar Observations
Chair: Frank Hill
Conference Room “Basel”
14:00 Markus Roth - Welcome
14:10 Lucia Kleint
Invited Talk: An Overview of Polarimetry
14:40 Roman Brajsa
Modeling Radiation from the Solar Atmosphere in the sub-mm, mm and cm Wavelength Range
15:00 Christopher J. Nelson
On The Relationship Between Ellerman Bombs and Other Solar Processes
15:20 Jan Langfellner
Anisotropy of the solar network magnetic field around the average supergranule
15:40 - 16:10 Coffee Break & Posters
16:10 Manfred Schüssler
The cause of the weak solar cycle 24
16:30 Rob Rutten
A new view of the Halpha chromosphere
16:50 Sanjay Gosain
Full Stokes Polarimeter for Chromospheric Measurements with SOLIS/VSM
17:10 Junwei Zhao
Establishing Connections between Photospheric Waves and Coronal Waves in Active Regions
17:30 Sanjay Gosain
A Proposal for Next Generation Synoptic Solar Instrumentation
17:50 Frank Hill
GONG Status
Tuesday - September 1, 2015 __________________________
08:30 Lobby Welcome Coffee
Session II: Solar and Stellar Modelling
Chair: Rudi Komm
Conference Room “Basel”
09:00 Matt Browning
Invited Talk: Global Simulations of solar and stellar dynamos: cycles, theories, and limits
09:30 Manfred Schüssler
The Babcock-Leighton solar dynamo
09:50 Jacobo Varela
Differential Rotation and Dynamo Action in Solar-like Stars
10:10 Zarzalt Magic
Inivted Talk: 3D MHD Stellar Atmosphere Simulations
10:40 - 11:10 Coffee Break & Posters
11:10 Laurene Jouve
Invited Talk: Models and data combined to progress towards a better understanding of the magnetism of solar-type stars
11:40 Volkmar Holzwarth
Joint magnetospheres of close "solar-twin" binary systems
12:00 Aditi Sood
Dynamical model for spindown of solar-type stars
12:20 Conference Photo
12:30-14:00 Lunch at Restaurant La Rotonde
Session III: Solar and Stellar Seismology
Chair: John Leibacher
Conference Room “Basel”
14:00 Ariane Schad
Invited Talk: Global helioseismic measurement of meridional circulation and differential rotation from mode eigenfunction perturbations
14:30 S.P. Rajaguru
Deep structure of solar meridional circulation: helioseismic inferences from four years of HMI/SDO observations
14:50 Ruizhu Chen
Measurement of deep solar meridional flow and its temporal variation
15:10 Dean-Yi Chou
Solar-Cycle Variations of Meridional Flows and Magnetic Signature at the Base of Convection Zone
15:30 Rosaria Simoniello
Helioseismic Signatures of the Progression of Solar Cycle: A Reflection of a Dynamo Wave
15:50-16:20 Coffee Break & Posters
16:20 Charles S. Baldner
Variations in Large-scale Flow Structures in the Current Solar Cycle
16:40 Rudolf Komm
Large-scale subsurface flows during Solar Cycle 23 and 24
17:00 Anne-Marie Broomhall
Statistical searches for low signal-to-noise oscillations
17:20 Kaori Nagashima
Measurement of the amplitude of the solar cross-covariance function
17:40 Vincent Böning
Validating Spherical Born Kernels for Meridional Flows
18:00 Björn Löptien
Data Compression for Helioseismology
Wednesday - September 2, 2015 _
08:30 Lobby Welcome Coffee
Session III: Solar and Stellar Seismology (continued)
Chair: Rekha Jain
Conference Room “Basel”
09:00 Damien Przybylski
Signatures of mode conversion in a sunspot simulation
09:20 Khalil Daiffallah
Helioseismology of sunspot models
09:40 Rudolf Komm
Subsurface helicity of active regions 12192 and 10486
10:00 Johannes Löhner Böttcher
Magnetic field reconstruction based on sunspot oscillations
10:20 - 10:50 Coffee Break & Posters
10:50 Ângela Santos
Contribution from sunspots to the observed frequency shifts
11:10 Kiran Jain
Response of Solar Oscillations to The Magnetic Activity: Comparison between Solar Cycles 23 and 24
11:30 Jesper Schou
What to do Next in Global Mode Seismology?
11:50 Packed Lunch
Excursion to Europa-Park Rust & Conference Dinner
12:45 Buses leave to Rust
13:30 Via the Entrance: Hotel El Andaluz entry into Europa-Park
20:00-23:00 Conference Dinner at Hotel Santa Isabella (Room: Convento)
23:00 Buses return to Freiburg
Thursday - September 3, 2015 ____________________
08:30 Lobby Welcome Coffee
Session III: Solar and Stellar Seismology (continued)
Chair: Conny Aerts
Conference Room “Basel”
09:00 Sarbani Basu
Invited Talk: Seismic inferences of solar and stellar structure
09:30 George Angelou
On the Utility of Diagrams of Small Frequency vs Large Frequency Separation
09:50 Elisabeth Guggenberger
Towards an improvement of the scaling relations
10:10 Mutlu Yildiz
Effects of the HeII ionization zones on oscillation frequencies and their promises
10:30 - 11:00 Coffee Break & Posters
11:00 Maria Bergemann
Invited Talk: Chemical abundances of the Sun and solar-like stars
11:30 Vincent Ballenegger
Thermodynamic properties of hydrogen and hydrogen-helium mixtures under solar conditions
11:50 Antonio Ferriz-Mas
Chandrasekhar's ‘adiabatic exponents’ and other material coefficients for stellar interiors
12:10 Ehsan Moravveji
Tight asteroseismic constraints on core overshooting and diffusive mixing for massive stars
12:30 Gaël Buldgen
Constraining mixing processes in 16CygA and 16CygB using Kepler data and seismic inversion
12:50 - 14:15 Lunch at Restaurant La Rotonde
Session IV: In Memory of Jean-Paul Zah
Chair: Eric Michel
Conference Room “Basel”
14:15 Stephane Mathis / Ian Roxburgh
Invited Talk: A Tribute to Jean-Paul Zahn
14:45 Sebastien Deheuvels
Invited Talk: What asteroseismology is teaching us about the internal rotation of stars
15:15 Santiago Andres Triana
The internal rotation of stars as revealed by asteroseismic inversions
15:35 Coffee Break & Posters
16:15 Vincent Prat
Ray dynamics of gravito-inertial modes in rapidly rotating stars
16:35 Paul G. Beck
Seismic analysis of red giant stars in binary systems - the heartbeat of red giants
16:55 Wiebke Herzberg
The effect of large scale flows on the eigenfrequencies of subgiant stars
17:15 Guy Davis
Invited Talk: Sounding solar and stellar activity cycles using asteroseismology
Friday - September 4, 2015 ___________
08:30 Lobby Welcome Coffee
Session IV: Solar and Stellar Activity
Chair: Guy Davis
Conference Room “Basel”
09:00 Thomas Ayres
Invited Talk: The Ups and Downs of Stellar Activity
09:30 Svetlana Berdyugina
Invited Talk: Overview on sunspots and starspots
10:00 Lousie Harra
Invited Talk: Review of solar flares
10:30-11:00 Coffee Break & Posters
11:00 Ralph Neuhäuser
Strong variations of 14-C around AD 775 and AD 1795 - due to solar activity
11:20 Manfred Kitze
Superflares on solar analogue stars
11:40 Rekha Jain
Oscillations in a solar coronal arcade near a flare-site
12:00 Alina Donea
Invited Talk: Seismicity induced by solar and stellar flares: comparison
12:30 Frederic Baudin
Flares and solar p-modes
12:50 Good-bye
13:00-14:00 Lunch at Restaurant La Rotonde
14:00 Conference Room "Basel" left
Splinter III: Open-access tools for local helioseismology provided by SpaceInn
14:00 Conference Room "Basel" right
Splinter IV: Meridional flow, α effect, single vs multiple dynamo: addressing open issues in solar/stellar dynamo with p-mode parameters
15:30-16:00 Coffee Break
17:00 End
SP) Splinter Sessions
Splinter sessions are organized on Monday morning (9:00 - 12:30) and Friday afternoon (14:00 - 18:00).
Splinter I: Comparing and Validating Meridional Flow Derivations in the Solar Convection Zone
Organisers
Junwei Zhao (Stanford University)
Markus Roth (Kiepenheuer-Institut für Sonnenphysik)
Abstract
Solar interior rotation and meridional flow are global-scale flows that control magnetic field generation, amplification, and transport inside the Sun. While the interior rotation profiles have long been solved through the global helioseismology method, a precise determination of the meridional flow in the deep solar interior only witnessed significant progresses recently. After removing a systematic center-to-limb effect through an empirical method, Zhao et al. (2013, ApJ Lett, 774, L29) detected a shallower-than-expected equatorward flow andfound evidences of a double-cell circulation using time-distance helioseismology. At about the same time, by use of a newly developed method based on global modes, Schad et al. (2013, ApJ Lett, 778, L38) found multi-cell circulation structures in both radial and latitudinal directions. Despite these advances, substantial differences remain in results obtained from these two abovementioned methods. It is important as well as necessary for the HELAS VII workshop participants, who are interested in meridional-flow studies, to hold a splinter session with a hope to further compare and validate their research methods.
The following topics will be discussed in the splinter session:
1. Compare results obtained from recent analyses using time-distance and global-mode methods. Identify similarities and differences in these results, and discuss what can be done to resolve these differences.
2. Some numerical simulation data, including single-cell, double-cell, and multi-cell models, will be made available to the participants and maybe the wider community for the purpose of validating different methods. For each set of simulation, the original simulation data and the data after an artificial center-to-limb effect is added will be provided, so that the effectiveness of the center-to-limb effect-removal method will also be evaluated.
3. All current inversions using time-distance measured travel-time shifts employ ray-approximation kernels, and a more complicated Born-approximation kernel is expected to offer more robust inversion results. The splinter session will discuss the current status and availability of Born approximation kernels, and explore the possibility of incorporating these kernels in the time-distance inversion processes.
Programme
Monday August 31, 2015; Meeting Room “Colmar”
9:30-9:40 Ariane Schad:
Updates on meridional-flow results using global modes
9:40-9:50 Ruizhu Chen:
Updates on time-distance meridional flow results
9:50-10:00 Paul Rajaguru:
Recent results on meridional flow using time-distance analysis
10:00-10:20 Discussion:
Comparison of results from different methods and how to further compare results from different groups
10:20-10:30 Junwei Zhao:
Global-scale simulation to validate meridional-flow analysis
10:30-10:50 Discussion:
How to use the simulation data to validate different analysis methods, and what more are needed from simulations
10:50 -11:10 Coffee
11:10-11:20 Jesper Schou:
The nature of the center-to-limb effect
11:20-11:40 Discussion:
Is there a better way to remove the center-to-limb effect?
11:40-11:50 Dean-Yi Chou:
Surface magnetic effects on meridional flow measurements
11:50-12:10 Discussion:
What is the best strategy to remove the magnetic effect from local- and global-helioseismology method?
12:10-12:20 Vincent Böning:
Born- versus ray-approximation kernels for the meridional flow
12:20-12:40 Discussion:
What are advantages for each kernel, and how we can incorporate the Born-kernel in the inversion?
Organisers
Tamara Rogers (Newcastle University, UK)
Conny Aerts (Leuven University, B)
Abstract
Waves are as ubiquitous in stars as they are on Earth. Just as on Earth, waves can transport angular momentum and mix species within stellar interiors, steering their rotational and chemical evolution. Waves also set up standing modes which can be observed through helio- and asteroseismology. Helioseismology has revolutionized our picture of the Sun, constraining the internal rotation profile and convective undershooting in the solar interior. Asteroseismology is not far behind, recently constraining core-envelope differential rotation and core convective overshooting in more massive stars. Indeed, the observations of waves through helio- and asteroseismology places the tightest constraints on the dynamical evolution those same waves induce.
This 3-hour splinter session aims to bring together researchers doing theory, simulations, and observations of waves in stars (gravity, pressure and mixed) with the hope that the synergy between the three (often disparate) fields could lead to tests and comparisons which would further our understanding of stellar interiors. Moreover, we include also studies of wave generation by convection in laboratory experiments to search for connections between those and stellar physics. We begin this session with four short talks on each of the sub-topics and will then continue with a guided discussion on how these fields can work together to advance our understanding.
Programme
Monday 31 August, 09:25 - 12:30; Conference Room “Basel”
09:25 Welcome
09:30 - 10:00 Theory: Stephane Mathis (Saclay, France)
10:00 - 10:30 Simulations: Tami Rogers (Newcastle, UK)
10:30 - 11:00 Coffee Break
11:00 - 11:15 Observational Signatures: Conny Aerts (Leuven, B)
11:15 - 11:30 Lab Experiments: Santiago Andres Triana (Leuven, B)
11:30 - 12:15 Guided discussion, participants are encouraged to bring 1 slide
12:15 - 12:30 Summary of Synergies & Future Steps
Splinter Session III: Open-access tools for local helioseismology provided by SpaceInn
Organisers
Vigeesh Gangadharan (Kiepenheuer-Institut, Freiburg)
Kaori Nagashima (Max-Planck-Institut für Sonnensystemforschung)
Markus Roth (Kiepenheuer-Institut, Freiburg)
Abstract
The SpaceInn project plans to provide archival data and analyses tools for local helioseismology. A collection of data sets is already available through the project for carrying out various helioseismic studies. Providing such a standard data set also allows comparison between different techniques used in local helioseismology. Additionally, a basic set of tools to handle the data is also being made available for researchers and novices in the field. The project ultimately aims to build a comprehensive and easily accessible toolkit that will enable the community to fully exploit the data provided by space- and ground-based observations.
In this splinter session, we will introduce a few tools that are currently available through SpaceInn. We also plan to discuss on the development of these tools in an open-source/access framework and in a more collaborative environment that will allow us to set benchmarks for comparison and reproducibility of results. This is also intended to serve as a platform to bring together researchers willing to share/contribute their expertise/tools and those who want to explore the data for their specific studies.
Programme
Friday, Sep 4, 2015; Conference Room "Basel" left
14:00 - 14:20 Introduction to tools on the SPACEINN WP4 - Kaori Nagashima
14:20 - 15:00 Fourier-Hankel/Legendre pipeline - Vigeesh Gangadharan
Fourier-Hankel/Legendre analysis is one of the helioseismic techniques employed to infer the internal properties of the Sun. It has been successfully applied to study p-mode interaction with sunspots and to measure sub-surface meridional flow. As part of SpaceInn project, we have implemented a new Fourier-Hankel/Legendre analysis module on the SDO/HMI JSOC data-analysis pipeline. We will present the details of the module and some preliminary results. We will also discuss on its applicability to meridional flow, differential rotation measurements and active region seismology.
15:00 - 15:30 Discussion
15:30 - 16:00 Coffee Break
16:00 - 17:30 Discussion (Contd.)
The main goal of the discussion session will be:
i) To review the collection of dataset and tools provided by the SpaceInn project available at: http://www2.mps.mpg.de/projects/seismo/SpaceInn/index.html
To get feedback on issues and suggestions for improvement of these dataset and tools. To compile a list of requested updates and additional tools (for e.g. mode fitting and inversion routines) for future use. To discuss updates to the information collected on systematic effects (approx. 30 min).
ii) To provide an overview on how these tools can be used for local helioseismology. To identify other science goals and to obtain relevant resources (codes from other researchers) needed to address them and to provide them as part of the project. To discuss on copyright and other issues of providing these resources in an open-access/source platform (approx. 30 min).
iii) To plan on migrating to a public repository (for e.g. git) in order to maintain all the current and planned codes and their future updates. To discuss on developing these tools into a more comprehensive toolkit (approx. 30 min).
Those interested in attending this splinter session may contact:
Kaori Nagashima (nagashima@mps.mpg.de) or
Vigeesh Gangadharan (vigeesh@kis.uni-freiburg.de).
Organiser
Rosaria Simoniello (Geneva Observatory, CH)
Abstract
The onset of solar cycle at mid-latitudes, the slow down of the sunspot drift toward the equator and the overlap of successive cycles at the time of activity minimum are delicate issues in αΩ and flux transport dynamo models. Very different parameter values produce similar results, making difficult the goal of achieving a unified dynamo model. To overcome this limit the role of α effect with respect to meridional flows has to be clarified. Within this context, helioseismology may play a key role. In fact, flux transport dynamo models also predict a slowing down of the sunspots towards the equator (Hathaway et al. 2003) and the beginning of a new cycle at higher latitudes before sunspot eruptions of the old cycle terminates at low latitudes. This leads to a tail-like attachment in the butterfly diagram (Nandy et al. 2002, Chatterjee et al. 2004). The classical description of α dynamo wave does predict the slow down of sunspot velocity drift as well as overlapping cycle (Schussler et al. 2004), whose properties are different from the ones predicted by flux transport dynamo model.
Low and high degree acoustic p-mode parameters are the perfect diagnostic tool to infer these specific properties. Therefore it is important as well as necessary for the HELAS VII workshop participants, who are involved in low and high degree p-mode parameter analysis, to hold a splinter session with the aim to identify the open issues in solar dynamo which can be naturally addressed by looking at mode frequencies, widths and amplitudes.
Programme
Friday, September 4, 2015; Conference Room “Basel” right
The following topics will be covered in the splinter session:
• 14.00-14.45 The progression of solar cycle as seen in low and high degree modes
How does it evolve the solar cycle at different latitudes? Are there any differences in the progression of solar cycle in the individual component of low degree modes (ℓ=0,1,2)? If yes what do they tell us? How do they agree or not with the analysis of intermediate/high degree modes?
• 14.45-15.30: On the origin of multiple magnetic cycles
Single dynamo or multiple dynamos: are the 11 and 2 yr cycle signatures of two distinct dynamos operating in the Sun (Benevolenskaja et al. 1998) or instead just only an amplitude modulation of the dipolar/quadrupolar component (Tobias et al. 1997)?
• 16.00-16.45: The cycle length variations
There are significant variations over the 11 and 2 year cycle length. This is an important diagnostic tool for dynamo probe. How does it change the length of the 11 yr with respect to the 2 year cycle length (Charboennau et al. 2015, in preparation)?
• 16.45-17.30 Frequency shift as activity proxy over the different phases of solar cycle
Minimum/Maximum: are the two phases where the correlation with activity proxies gets worse. Why is that? Is another mechanism contributing to solar dynamo? Local dynamo or what else?
• 17.30-18.00: Summary and Conclusions
This splinter session is seen as an opportunity to exchange ideas and discuss how to further collaborate on the above-mentioned topics. In this 3-hour session, we expect presentations on voluntary bases from anyone willing to shows 1-2 plots, figures which will stimulate discussions and will foster collaborations within the helioseismic community dealing with low and high degree modes.
Anyone willing to participate and/or present their plots/figures needs just to send an e-mail at rosaria.simoniello@unige.ch in order to organize the session.
P) Poster Session
Posters will be on display the whole week.
The poster format is A0 portrait (width x height: 841 × 1189 mm).