Magnetic fields in single late-type giants in the Solar vicinity: How common is magnetic activity on the giant branches?

We present our first results on a new sample containing all single G, K and M giants down to V = 4 mag in the Solar vicinity, suitable for spectropolarimetric (Stokes V) observations with Narval at TBL, France. For detection and measurement of the magnetic field (MF), the Least Squares Deconvolution (LSD) method was applied (Donati et al. 1997) that in the present case enables detection of large-scale MFs even weaker than the solar one (the typical precision of our longitudinal MF measurements is 0.1-0.2 G). The evolutionary status of the stars is determined on the basis of the evolutionary models with rotation (Lagarde et al. 2012; Charbonnel et al., in prep.) and fundamental parameters given by Massarotti et al. (1998). The stars appear to be in the mass range 1-4 M ⊙, situated at different evolutionary stages after the Main Sequence (MS), up to the Asymptotic Giant Branch (AGB). The sample contains 45 stars. Up to now, 29 stars are observed (that is about 64% of the sample), each observed at least twice. For 2 stars in the Hertzsprung gap, one is definitely Zeeman detected. Only 5 G and K giants, situated mainly at the base of the Red Giant Branch (RGB) and in the He-burning phase are detected. Surprisingly, a lot of stars ascending towards the RGB tip and in early AGB phase are detected (8 of 13 observed stars). For all Zeeman detected stars v sin i is redetermined and appears in the interval 2-3 km/s, but few giants with MF possess larger v sin

Monitoring of the magnetic field topology and activity of the core helium-burning giant beta Ceti in the period 2010-2013

Beta Ceti is a slowly rotating (v sin i = 3.5 kms−1) single giant. In our previous study (Tsvetkova et al. (2013)) we showed that it is in the core He-burning phase and we reconstructed two Zeeman Doppler imaging (ZDI) maps (using data from 2010 and 2011) revealing a simple large-scale magnetic field structure. We concluded that the magnetic field of beta Ceti could have a fossil field origin. In addition, the study of Aurière et al. (2015) about the properties and origin of the magnetism of late-type giants, where beta Ceti was a member of that sample, revealed that this star did not follow the general trends for dynamo-generated magnetic fields. Now, we present a new ZDI map of beta Ceti and compare the new results with our previous study. This monitoring for several years of the magnetic field topology and line activity indicators variability supports our previous conclusion about the fossil field origin of the magnetic field of beta Ceti

Performing the six organ symphonies of Louis Vierne

In this thesis I focus on Louis Vierne’s Six Symphonies for Organ. In the Introduction I make a historical overview of the epoch in which Vierne lived and composed his works. I list the dispositions of the organ at the Notre-Dame Cathedral during the time Vierne was organist there, because of the importance that this instrument has for Vierne as a musician. In the second part of the thesis I focus on my interpretation of the symphonies. I explore some of Vierne’s thoughts about organ playing and I make my own commentaries, which are based on my own experience of playing Vierne’s music. I also use my own recordings, which I made during the period that I studied the symphonies and during my concert series of the pieces in order to illustrate the different aspects of my interpretation

Monitoring of the magnetic field topology and activity of the core helium-burning giant β Ceti in the period 2007 - 2013

International audienceWe present a second spectropolarimetric study dedicated to the single giant β Ceti. Adding new data to our previously published data, we are able to trace the evolution of the magnetic activity of the giant for the period from 2007 to 2013. We apply the same data reduction procedures and methods as in our earlier study, so we could reliably compare the results. We reconstruct a third magnetic map, applying the Zeeman Doppler imaging (ZDI) method. From our new observations we recover a dipolar magnetic topology similar to that obtained previously, supporting the long-term stability of the large-scale magnetic field of β Ceti. To visualise the magnetic field lines that extend above the surface, we perform field extrapolations using a potential field method. In contrast to the large-scale field, the behaviour of the activity indicators Hα, Ca II H&K and Ca II IRT suggests an evolution of the small-scale magnetic structures in the chromosphere. This study presents for the first time a long-term monitoring of the magnetic activity of a probable Ap star descendant, which confirms the stability of its large-scale magnetic field