ELFT HÍRADÓ

[ilka AT konkoly.hu (Kalman Belane)]

                            Meghivo

      az MTA Konkoly Thege Miklos Csillagaszati Kutatointezete
                         szeminariumara


Eloado: Dr. KATRIEN KOLENBERG                                                 
          
        University of Vienna                                                  
          
                                                                              
  
Cim:"A SPECTROSCOPIC STUDY OF THE BLAZHKO EFFECT IN RR LYRAE STARS"           
        
                                                                              
                                                                              
    
About 20-30% of the (galactic) fundamental mode as well as 2-5% of            
  
the first overtone RR Lyrae stars show a periodic modulation of their         
 
light curve shape on a timescale of typically tens of days. Though            
  
this phenomenon, known as the Blazhko effect, was discovered almost           
  
a century ago, a widely acceptable theoretical model for its physical origin
is still lacking. Most viable models for explaining the amplitude and/or
phase modulation involve either a magnetic field or a resonance          
effect. In both types of models nonradial oscillations play an essential      
  
role. Their presence is not easy to establish observationally in the          
  
dominantly radially pulsating RR Lyrae stars.                      
                                                                              
              
Throughout this talk the results of a spectroscopic study of the              
  
Blazhko effect, the first of its kind, in the brightest Blazhko star          
  
RR Lyrae will be presented. A period analysis performed on a set              
  
of high-resolution line profiles of the star implied strong evidence          
  
for the presence of nonradial oscillation modes. We concentrated on           
  
their precise identification, considering different approaches to             
  
unravel the nonradial modes from our spectra. The adopted methods          
will be discussed, paying attention to the elements that can still            
  
be enhanced by a deeper theoretical insight, and pointing out the             
  
obtained results. We end with the conclusions in the framework of             
  
the studies on the Blazhko effect and the outlook for future projects.        
  

A szeminarium idopontja: 2003. marcius 13. 14 ora

Helyszine: MTA Konkoly Thege Miklos Csillagaszati Kutatointezete
           1121 Budapest Konkoly Thege M. ut 13-17.  


                                      Patkos Laszlo s.k.