Helio and Astero-Seismology and Exoplanets Search

    General
    Description

    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.

    Principal investigator

    Milestones

    1. 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".
    2. 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).
    3. 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.
    4. 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.

    Related publications

    Weighing stars from birth to death: mass determination methods across the HRD 2021A&ARv..29....4S
    A transmission spectrum of the planet candidate WD 1856+534 b and a lower limit to its mass 2021A&A...649A.131A
    Spectroscopic and seismic analysis of red giants in eclipsing binaries discovered by Kepler 2021A&A...648A.113B
    ROOSTER: a machine-learning analysis tool for Kepler stellar rotation periods 2021A&A...647A.125B
    Precise radial velocities of giant stars. XV. Mysterious nearly periodic radial velocity variations in the eccentric binary ε Cygni 2021A&A...647A.160H
    Probing the internal magnetism of stars using asymptotic magneto-asteroseismology 2021A&A...647A.122M
    TOI-257b (HD 19916b): a warm sub-saturn orbiting an evolved F-type star 2021MNRAS.502.3704A
    Observing the changing surface structures of the active K giant σ Geminorum with SONG 2021A&A...646A...6K
    Search for flares and associated CMEs on late-type main-sequence stars in optical SDSS spectra 2021A&A...646A..34K
    Prospects for Galactic and stellar astrophysics with asteroseismology of giant stars in the TESS continuous viewing zones and beyond 2021MNRAS.502.1947M
    An Intermediate-age Alpha-rich Galactic Population in K2 2021AJ....161..100W
    A planetary system with two transiting mini-Neptunes near the radius valley transition around the bright M dwarf TOI-776 2021A&A...645A..41L
    A Modified Kwee─Van Woerden Method for Eclipse Minimum Timing with Reliable Error Estimates 2020Galax...9....1D
    The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Data 2021AJ....161...36B
    Properties of the Hyades, the eclipsing binary HD 27130, and the oscillating red giant ∊ Tauri 2021A&A...645A..25B
    Maintaining the Ephemeris of 20 CoRoT Planets: Transit Minimum Times and Potential Transit Timing Variations 2020JAVSO..48..201D
    The K2 Galactic Archaeology Program Data Release 2: Asteroseismic Results from Campaigns 4, 6, and 7 2020ApJS..251...23Z
    What future awaits the Sun? 2020Sci...368..466S
    The hot dayside and asymmetric transit of WASP-189 b seen by CHEOPS 2020A&A...643A..94L
    Robust asteroseismic properties of the bright planet host HD 38529 2020MNRAS.499.6084B
    The TOI-763 system: sub-Neptunes orbiting a Sun-like star 2020MNRAS.498.4503F
    π Earth: A 3.14 day Earth-sized Planet from K2's Kitchen Served Warm by the SPECULOOS Team 2020AJ....160..172N
    The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESS 2020ApJ...900..154M
    K2-280 b - a low density warm sub-Saturn around a mildly evolved star 2020MNRAS.497.4423N
    Rotation of Solar Analogs Crossmatching Kepler and Gaia DR2 2020ApJ...898..173D
    The Sixth Data Release of the Radial Velocity Experiment (RAVE). II. Stellar Atmospheric Parameters, Chemical Abundances, and Distances 2020AJ....160...83S
    The Sixth Data Release of the Radial Velocity Experiment (RAVE). I. Survey Description, Spectra, and Radial Velocities 2020AJ....160...82S
    The Multiplanet System TOI-421 2020AJ....160..114C
    Asteroseismic masses of four evolved planet-hosting stars using SONG and TESS: resolving the retired A-star mass controversy 2020MNRAS.496.5423M
    Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap? 2020A&A...639A.132B
    An eclipsing substellar binary in a young triple system discovered by SPECULOOS 2020NatAs...4..650T
    The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra 2020ApJS..249....3A
    The CARMENES search for exoplanets around M dwarfs. A super-Earth planet orbiting HD 79211 (GJ 338 B) 2020A&A...637A..93G
    Spectroscopic and Asteroseismic Analysis of the Secondary Clump Red Giant HD 226808 2020ApJ...894...67D
    Doppler Imaging and Differential Rotation of σ<SUP>2</SUP> Coronae Borealis Using SONG 2020ApJ...893..164X
    Three planets transiting the evolved star EPIC 249893012: a hot 8.8-M<SUB>⊕</SUB> super-Earth and two warm 14.7 and 10.2-M<SUB>⊕</SUB> sub-Neptunes 2020A&A...636A..89H
    TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission 2020AJ....159..151S
    Age dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi 2020NatAs...4..382C
    TESS Spots a Hot Jupiter with an Inner Transiting Neptune 2020ApJ...892L...7H
    Transiting exoplanets from the CoRoT space mission. XXIX. The hot Jupiters CoRoT-30 b and CoRoT-31 b 2020A&A...635A.122B
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