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

    A fresh look at the seismic spectrum of HD49933: analysis of 180 days of CoRoT photometry 2009A&A...507L..13B
    Solar-like oscillations with low amplitude in the CoRoT target HD 181906 2009A&A...506...41G
    Seismic and spectroscopic characterization of the solar-like pulsating CoRoT target HD 49385 2010A&A...515A..87D
    Green's Functions for Far-Side Seismic Images: A Polar-Expansion Approach 2010ApJ...711..853P
    Empirical Determination of Convection Parameters in White Dwarfs. I. Whole Earth Telescope Observations of EC14012-1446 2012ApJ...751...91P
    Angular momentum transfer between oscillations and rotation in subdwarf B hybrid pulsators 2011A&A...535A..96P
    The onset of solar cycle 24. What global acoustic modes are telling us 2009A&A...504L...1S
    The GOLF-NG prototype and the solar European perspective for cosmic vision 2015-2025 2008JPhCS.118a2044T
    The Asteroseismic Potential of Kepler: First Results for Solar-Type Stars 2010ApJ...713L.169C
    The Acoustic Cutoff Frequency of the Sun and the Solar Magnetic Activity Cycle 2011ApJ...743...99J
    p-mode power variation with solar atmosphere as observed in the Na D1 and K spectral lines 2008AN....329..494S
    HELAS IT-platform: A new tool for the European Helio- and Asteroseismology community. 2008CoAst.153..108J
    The pulsation modes of the pre-white dwarf PG 1159-035 2008A&A...477..627C
    The pulsating hot subdwarf Balloon 090100001: results of the 2005 multisite campaign 2009MNRAS.392.1092B
    Testing the evolution of the DB white dwarf GD 358: first results of a new approach using asteroseismology 2009A&A...493.1067G
    On the Possible Existence of Short-Period g-Mode Instabilities Powered by Nuclear-Burning Shells in Post-Asymptotic Giant Branch H-Deficient (PG1159-Type) Stars 2009ApJ...701.1008C
    A survey for pulsating subdwarf B stars with the Nordic Optical Telescope 2010A&A...513A...6O
    A peculiar Of star in the Local Group galaxy IC 1613 2012A&A...543A..85H
    Update on g-mode research 2008AN....329..476G
    The solar core as never seen before 2011JPhCS.271a2043E
    The rotation rate and its evolution derived from improved mode fitting and inversion methodology 2011JPhCS.271a2067K
    Sensitivity of helioseismic gravity modes to the dynamics of the solar core 2008A&A...484..517M
    New insights on the solar core 2011JPhCS.271a2046G
    Influence of Low-Degree High-Order p-Mode Splittings on the Solar Rotation Profile 2008SoPh..251..119G
    HD 172189: another step in furnishing one of the best laboratories known for asteroseismic studies 2009A&A...507..901C
    Detection and temporal coherence of p-modes below 1.4 mHz 2008AN....329..470E
    Comparative analysis of the impact of geological activity on the structural design of telescope facilities in the Canary Islands, Hawaii and Chile 2010MNRAS.407.1361E
    Analysis of the Sensitivity of Solar Rotation to Helioseismic Data from GONG, GOLF, and MDI Observations 2008ApJ...679.1636E
    Advances in solar rotation rate inferences: Unstructured grid inversions and improved rotational splittings 2010AN....331..890E
    Accurate Mapping of the Torsional Oscillations: a Trade-Off Study between Time Resolution and Mode Characterization Precision 2011JPhCS.271a2078E
    A devil in the detail: parameter cross-talk from the solar cycle and estimation of solar p-mode frequencies 2008MNRAS.385.1605C
    Using Stellar Densities to Evaluate Transiting Exoplanetary Candidates 2011ApJ...726..112T
    Transiting exoplanets from the CoRoT space mission. XXIII. CoRoT-21b: a doomed large Jupiter around a faint subgiant star 2012A&A...545A...6P
    Transiting exoplanets from the CoRoT space mission. XXII. CoRoT-16b: a hot Jupiter with a hint of eccentricity around a faint solar-like star 2012A&A...541A.149O
    Transiting exoplanets from the CoRoT space mission. XXI. CoRoT-19b: a low density planet orbiting an old inactive F9V-star 2012A&A...537A.136G
    Transiting exoplanets from the CoRoT space mission. XX. CoRoT-20b: A very high density, high eccentricity transiting giant planet 2012A&A...538A.145D
    Transiting exoplanets from the CoRoT space mission. XVIII. CoRoT-18b: a massive hot Jupiter on a prograde, nearly aligned orbit 2011A&A...533A.130H
    Transiting exoplanets from the CoRoT space mission. XVII. The hot Jupiter CoRoT-17b: a very old planet 2011A&A...531A..41C
    Transiting exoplanets from the CoRoT space mission. XVI. CoRoT-14b: an unusually dense very hot Jupiter 2011A&A...528A..97T
    Transiting exoplanets from the CoRoT space mission. XV. CoRoT-15b: a brown-dwarf transiting companion 2011A&A...525A..68B
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