General
The principal objectives of this project are: 1) to study the structure and dynamics of the solar interior, 2) to extend this study to other stars (either single or in binary systems), 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and, their characterization with complementary radial velocity information.
To reach our first objective, we use Helioseismology (analysis of the solar oscillation eigenmodes), a technique that enables us to infer the Sun's internal structure and dynamics with high accuracy. This project covers the various aspects necessary to attain the aforementioned objectives: instrumental and observational (with the international networks BiSON and GONG operating at the ”SolarLab” at Observatorio del Teide), reduction, analysis, and interpretation of data (in particular, the GOLF and VIRGO instruments aboard ESA/SoHO satellite). Finally, theoretical developments in inversion techniques are carried out.
Furthermore, Asteroseismology applies similar techniques to other oscillating stars to infer their evolutionary state as well as their internal structure and dynamics. Thanks to the high-quality photometric data collected by the CoRoT, Kepler, and TESS space missions, it is possible to extract global seismic parameters for hundreds of thousands of solar-like stars, from the main sequence through the red-giant phase. Stellar evolution models are used to find the model that best fits the observables (spectroscopic and individual mode frequencies), providing precise mass, radius, and age for the star. Binary stars provide additional strong constraints on these models and therefore allow testing the intricacies of internal stellar physics.
Precise exoplanet characterization is critically dependent on an accurate knowledge of the host star. In particular, a reliable determination of the stellar age is required to constrain the age and evolutionary state of the planetary system, and to place robust limits on long-term habitability. At the interface between asteroseismology and exoplanet science, detailed seismic modeling of host stars is used to refine the ages of planetary systems. Strong involvement is ensured in the preparation of the ESA PLATO mission (launch expected at the end of 2026), including light-curve calibration, contributions to the science calibration and validation input catalog (scvPIC), proposals for complementary science, and ground-based follow-up observations.
For this project, ground-based observations with the observational facilities available to IAC researchers, in particular at OCAN (Observatorios de Canarias), are key. In particular, ongoing observations with the ground-based, high-precision spectrographs on the SONG (Stellar Observations Network Group) and the Las Cumbres Observatory Network (LCO) are being conducted to improve the spectroscopic and seismic characterization of oscillating stars and to identify binary systems.
Members
Results
Milestones
- Beck et al. (2024, A&A, 682, A7) increased the number of known solar-like oscillators in binary systems by about an order of magnitude. Such large sample allowed us to study the effects co-evolution of stellar evolution on the evolution of the binary orbits. Featured as "ESA Gaia image of the Week".
- Following the participation to the roadmaps in astrophysics for the ESA’s Human and Robotic Exploration Directorate in 2021, a paper in npj Microgravity was published where the key quetions in stellar physics were exposed along with proposed experiments for the future as part of that program (Mathur & Santos 2024).
- Merc et al. (2024, A&A, 683, A84) presented the first analysis of accretion-induced flickering variability in symbiotic binary stars from TESS lightcurves. This study significantly enlarged the known sample with such variability. This suggests that accretion disks are common in symbiotic stars.
- Solar magnetic activity in cycles 23&24 were analyzed by tracking GOLF low-degree p-mode frequency shifts across 3 bands, probing depths of 74–1575 km. Results suggest magnetic variations mainly occur near the surface. In cycle 24, shifts appeared earlier at high latitudes and coincided with surface activity near the equator, with stronger shifts at shallower depths.
Scientific activity
Related publications
News