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

    The Kepler Follow-up Observation Program. II. Stellar Parameters from Medium- and High-resolution Spectroscopy 2018ApJ...861..149F
    Testing tidal theory for evolved stars by using red giant binaries observed by Kepler 2018MNRAS.479L.123B
    Oscillating red giants in eclipsing binary systems: empirical reference value for asteroseismic scaling relation 2018MNRAS.478.4669T
    HD 89345: a bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2 2018MNRAS.478.4866V
    The envelope of the power spectra of over a thousand δ Scuti stars. The T̅eff - νmax scaling relation 2018A&A...614A..46B
    The mass and age of the first SONG target: the red giant 46 LMi 2018A&A...613A..53F
    Seismic probing of the first dredge-up event through the eccentric red-giant and red-giant spectroscopic binary KIC 9163796. How different are red-giant stars with a mass ratio of 1.015? 2018A&A...612A..22B
    Low-frequency photospheric and wind variability in the early-B supergiant HD 2905 2018A&A...612A..40S
    Frequency dependence of p-mode frequency shifts induced by magnetic activity in Kepler solar-like stars 2018A&A...611A..84S
    K2 photometry and HERMES spectroscopy of the blue supergiant ρ Leo: rotational wind modulation and low-frequency waves 2018MNRAS.476.1234A
    Non-grey dimming events of KIC 8462852 from GTC spectrophotometry 2018A&A...610L..12D
    The First Post-Kepler Brightness Dips of KIC 8462852 2018ApJ...853L...8B
    The Influence of Metallicity on Stellar Differential Rotation and Magnetic Activity 2018ApJ...852...46K
    Photospheric activity of the Sun with VIRGO and GOLF. Comparison with standard activity proxies 2017A&A...608A..87S
    Asteroseismic masses of retired planet-hosting A-stars using SONG 2017MNRAS.472.4110S
    Search for rings and satellites around the exoplanet CoRoT-9b using Spitzer photometry 2017A&A...603A.115L
    Asymptotic g modes: Evidence for a rapid rotation of the solar core 2017A&A...604A..40F
    Atmospheric Extinction Coefficients in the Ic Band for Several Major International Observatories: Results from the BiSON Telescopes, 1984-2016 2017AJ....154...89H
    On the signatures of flare-induced global waves in the Sun: GOLF and VIRGO observations 2017MNRAS.471.4677K
    A deeper view of the CoRoT-9 planetary system. A small non-zero eccentricity for CoRoT-9b likely generated by planet-planet scattering 2017A&A...603A..43B
    Limits to the presence of transiting circumbinary planets in CoRoT Data 2017A&A...602A.117K
    Evidence of chaotic modes in the analysis of four δ Scuti stars 2017A&A...601A..57B
    Kepler observations of the asteroseismic binary HD 176465 2017A&A...601A..82W
    Kepler sheds new and unprecedented light on the variability of a blue supergiant: Gravity waves in the O9.5Iab star HD 188209 2017A&A...602A..32A
    Internal rotation of 13 low-mass low-luminosity red giants in the Kepler field 2017A&A...602A..62T
    CoRoT 223992193: Investigating the variability in a low-mass, pre-main sequence eclipsing binary with evidence of a circumbinary disk 2017A&A...599A..27G
    First Results from the Hertzsprung SONG Telescope: Asteroseismology of the G5 Subgiant Star μ Herculis 2017ApJ...836..142G
    TEE, an estimator for the precision of eclipse and transit minimum times 2017A&A...599A..93D
    Asteroseismology of Solar-Type Stars with K2: Detection of Oscillations in C1 Data 2015PASP..127.1038C
    Transiting exoplanets from the CoRoT space mission⋆. XXVIII. CoRoT-33b, an object in the brown dwarf desert with 2:3 commensurability with its host star 2015A&A...584A..13C
    HD 144548: A young triply eclipsing system in the Upper Scorpius OB association 2015A&A...584L...8A
    Analysis of the acoustic cut-off frequency and high-frequency peaks in six Kepler stars with stochastically excited pulsations 2015A&A...583A..74J
    A seismic and gravitationally bound double star observed by Kepler. Implication for the presence of a convective core 2015A&A...582A..25A
    Evidence of amplitude modulation due to resonant mode coupling in the δ Scuti star KIC 5892969. A particular or a general case? 2015A&A...579A.133B
    Transiting exoplanets from the CoRoT space mission. XXVII. CoRoT-28b, a planet orbiting an evolved star, and CoRoT-29b, a planet showing an asymmetric transit 2015A&A...579A..36C
    Period, epoch, and prediction errors of ephemerides from continuous sets of timing measurements 2015A&A...578A..17D
    Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star 2015A&A...576A..11G
    The two-colour EMCCD instrument for the Danish 1.54 m telescope and SONG 2015A&A...574A..54S
    Kepler-432 b: a massive warm Jupiter in a 52-day eccentric orbit transiting a giant star 2015A&A...573L...6O
    The PLATO 1.0 mission 2014ExA....38..249R
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    Componentes del experimento PLATO
    PLATO (PLAnetary Transits and Oscillations of stars)
    PLAnetary Transits and Oscillations of stars (PLATO) is the third medium-class mission in ESA's Cosmic Vision programme. Its objective is to find and study a large number of extrasolar planetary systems, with emphasis on the properties of terrestrial planets in the habitable zone around solar-like stars
    Hans Jörg
    Deeg Deeg