The prototype telescope and instruments for the Stellar Observations Network Group (SONG) are nearing completion at the Observatorio del Teide on Tenerife. In this contribution we describe the current status (autumn 2013) of the telescope and its instrumentation. Preliminary performance characteristics are presented for the high-resolution spectrograph based on daytime observations of the Sun and a 4 hour test series obtained for the sub-giant β Aquilae.

President of Commission 7 Zoran Knežević opened the business meeting at 18:40 and proposed the agenda which was accepted without change.

The study of variable stars in open clusters via asteroseismology is a powerful tool for the study of stellar evolution and stars in general. That is because stars in clusters can be assumed to originate from the same interstellar cloud, so they share similar properties such as age and overall metallicity. We performed a search for variable stars in the field of the young open star cluster Roslund 2, with photoelectric and CCD photometry acquired at two different telescopes. Within the resulting light curves we have found 12 variable stars. Our measurements confirm three previously known variables.

During the past decades, stellar oscillations and exoplanet searches were developed in parallel, and the observations were done with the same instruments: radial velocity method, essentially with ground-based instruments, and photometric methods (light curves) from space. The same observational data on one star could lead to planet discoveries at large time scales (days to years) and to the detection of stellar oscillations at small time scales (minutes), such as for the star μ Arae. Since the beginning, it seemed interesting to investigate the differences between stars with and without observed planets. Also, a precise determination of the stellar parameters is important to characterize the detected exoplanets. With the thousands of exoplanet candidates discovered by Kepler, automatic procedures and pipelines are needed with large data bases to characterize the central stars. However, precise asteroseismic studies of well-chosen stars are still important for a deeper insight.

We characterized the time intervals between the interchanges of the alternating high- and low-amplitude extrema of three RV Tauri and three RR Lyrae stars.

The power of asteroseismology relies on the ability to infer the stellar structure from the unambiguous frequency identification of the corresponding pulsation mode. Hence, the use of a Fourier transform is in the basis of asteroseismic studies. Nevertheless, the difficulties with the interpretation of the frequencies found in many stars lead us to reconsider whether Fourier analysis is the most appropriate technique to identify pulsation modes. We have found that the data, usually analyzed using Fourier techniques, present a non-analyticity originating from the lack of connectivity of the underlying function describing the physical phenomena. Therefore, the conditions for the Fourier series to converge are not fulfilled. In the light of these results, we examine in this talk some stellar light curves from different asteroseismology space missions (CoRoT, Kepler and SoHO) in which the interpretation of the data in terms of Fourier frequencies becomes difficult. We emphasize the necessity of a new interpretation of the stellar light curves in order to identify the correct frequencies of the pulsation modes.

We first present a brief description of the six distinct families of pulsating white dwarfs that are now known. These are all opacity-driven pulsators showing low- to mid-order, low-degree gravity modes. We then discuss some recent highlights that have come up in the field of white dwarf asteroseismology.

Follow-up (U)BVRI photometric observations have been carried out for 42 RR Lyrae stars in the Kepler field. The new magnitude and color information will complement the available extensive high-precision Kepler photometry and recent spectroscopic results. The photometric observations were made with the following telescopes: 1-m and 41-cm telescopes of Lulin Observatory (Taiwan), 81-cm telescope of Tenagra Observatory (Arizona, USA), 1-m telescope at the Mt. Lemmon Optical Astronomy Observatory (LOAO, Arizona, USA), 1.8-m and 15-cm telescopes at the Bohyunsan Optical Astronomy Observatory (BOAO, Korea) and 61-cm telescope at the Sobaeksan Optical Astronomy Observatory (SOAO, Korea). The observations span from 2010 to 2013, with ~200 to ~600 data points per light curve. Preliminary results of the Korean observations were presented at the 5th KASC workshop in Hungary. In this work, we analyze all observations. These observations permit the construction of full light curves for these RR Lyrae stars and can be used to derive multi-filter Fourier parameters.

The star HD 51844 was observed in the CoRoT LRa02 as a target in the seismology field, which turned out to be an SB2 system. The 117-day light curve revealed δ Scuti pulsations in the range of 6 to 15 d−1 where four frequencies have amplitudes larger than 1.4 mmag, and a rich frequency spectrum with amplitudes lower than 0.6 mmag. Additionally, the light curve exhibits a 3-mmag brightening event recurring every 33.5 days with a duration of about 5 days. The radial velocities from spectroscopy confirmed that the star is an eccentric binary system with nearly identical masses and physical parameters. The brightening event in the light curve coincides with the maximum radial-velocity separation showing that the brightening is in fact caused by tidal distortion and/or reflected light. One component displays large line-profile variations, while the other does not show significant variation. The frequency analysis revealed a quintuplet structure of the four highest-amplitude frequencies, which is due to the orbital motion of the pulsating star.

The Magnetism in Massive Stars (MiMeS) project represents the largest systematic survey of stellar magnetism ever undertaken. Based on a sample of over 550 Galactic B and O-type stars, the MiMeS project has derived the basic characteristics of magnetism in hot, massive stars. Herein we report preliminary results.

Selected events of the scientific biography of Wojtek Dziembowski are briefly described, and several related photos are presented. The full version of the presentation is available at the IAU Symposium 301 webpage.

We have previously calculated a number of 2D hydrodynamic simulations of convection and pulsation to full amplitude. These revealed a significantly better fit to the observed light curves near the red edge of the instability strip in the globular cluster M 3 than did previous 1D mixing length models. Here we compare those 2D results with our new 3D hydrodynamic simulations calculated with the same code. As expected, the horizontal spatial behaviour of convection in 2D and 3D is quite different, but the time dependence of the convective flux on pulsation phase is quite similar. The difference in pulsation growth rate is only about 0.1% per period, with the 3D models having more damping at each of the five effective temperatures considered. Full amplitude pulsation light curves in 2D and 3D are compared.

Stellar variability induced by starspots can hamper the detection of exoplanets and bias planet property estimations. These features can also be used to study star-planet interactions as well as inferring properties from the underlying stellar dynamo. However, typical techniques, such as ZDI, are not possible for most host-stars. We present a robust method based on spot modelling to map the surface of active star allowing us to statistically study the effects and interactions of stellar magnetism with transiting exoplanets. The method is applied to the active Kepler-9 star where we find small evidence for a possible interaction between planet and stellar magnetosphere which leads to a 2:1 resonance between spot rotation and orbital period.

κ1 Cet (HD 20630, HIP 15457, d = 9.16 pc, V = 4.84) is a dwarf star approximately 30 light-years away in the equatorial constellation of Cetus. Among the solar proxies studied in the Sun in Time, κ1 Cet stands out as potentially having a mass very close to solar and a young age. On this study, we monitored the magnetic field and the chromospheric activity from the Ca II H & K lines of κ1 Cet. We used the technique of Least-Square-Deconvolution (LSD, Donati et al. 1997) by simultaneously extracting the information contained in all 8,000 photospheric lines of the echelogram (for a linelist matching an atmospheric model of spectral type K1). To reconstruct a reliable magnetic map and characterize the surface differential rotation of κ1 Cet we used 14 exposures spread over 2 months, in order to cover at least two rotational cycles (Prot ~9.2 days). The Least Square deconvolution (LSD) technique was applied to detect the Zeeman signature of the magnetic field in each of our 14 observations and to measure its longitudinal component. In order to reconstruct the magnetic field geometry of κ1 Cet, we applied the Zeeman Doppler Imaging (ZDI) inversion method. ZDI revealed a structure in the radial magnetic field consisting of a polar magnetic spot. On this study, we present the fisrt look results of a high-resolution spectropolarimetric campaign to characterize the activity and the magnetic fields of this young solar proxy.

We present the preliminary results of the measurements of longitudinal magnetic field of the massive white dwarf 1658+441. This star have an hydrogen pure atmosphere (e.g. Dupuis & Chayer, 2003). We have observed the target in a total of 18 hrs during 3 consecutive nights in June 2010 and one more in May 2011. The data was acquired with a prototypical spectropolarimeter at the San Pedro Martir Telescope in Mexico. We have tested the magnetic field measurements with our instrument using the famous Babcock's star obtaining consistent results with previous studies. For our object of study, the WD 1658+441, we have measured variable intensities of the longitudinal magnetic field of Blong = 720 kG that oscillates with an amplitude of 130 kG.

The problem of interaction of stellar pulsations with turbulence and radiation in stellar convective envelopes is central to our understanding of excitation mechanisms, oscillation amplitudes and frequency shifts. Realistic (“ab initio”) numerical simulations provide unique insights into the complex physics of pulsation-turbulence-radiation interactions, as well as into the energy transport and dynamics of convection zones, beyond the standard evolutionary theory. 3D radiative hydrodynamics simulations have been performed for several Kepler target stars, from M- to A-class along the main sequence, using a new ‘StellarBox’ code, which takes into account all essential physics and includes subgrid scale turbulence modeling. The results reveal dramatic changes in the convection and pulsation properties among stars of different mass. For relatively massive stars with thin convective envelopes, the simulations allow us to investigate the dynamics the whole envelope convection zone including the overshoot region, and also look at the excitation of internal gravity waves. Physical properties of the turbulent convection and pulsations, and the oscillation spectrum for two of these targets are presented and discussed in this paper. In one of these stars, with mass 1.47 M⊙, we simulate the whole convective zone and investigate the overshoot region at the boundary with the radiative zone.

The dynamo process is believed to drive the magnetic activity of stars like the Sun that have an outer convection zone. Large spectroscopic surveys showed that there is a relation between the rotation periods and the cycle periods: the longer the rotation period is, the longer the magnetic activity cycle period will be. We present the analysis of F stars observed by Kepler for which individual p modes have been measure and with surface rotation periods shorter than 12 days. We defined magnetic indicators and proxies based on photometric observations to help characterise the activity levels of the stars. With the Kepler data, we investigate the existence of stars with cycles (regular or not), stars with a modulation that could be related to magnetic activity, and stars that seem to show a flat behaviour.