SCIENTIFIC PROGRAMME  

 

Conference Programme (pdf file)

 
 

Conference Flyer

 

 

Abstracts Book (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?

 

Splinter Session II: Waves inside Stars: Theory, Simulations, Observational Signatures, and Lab Experiments

 

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).

 

Splinter IV: Meridional flow, α effect, single vs multiple dynamo: addressing open issues in solar/stellar dynamo with p-mode parameters  

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).