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, 3) to search for extrasolar planets using photometric methods (primarily by transits of their host stars) and their characterization (using radial velocity information) and 4) the study of the planetary atmospheres.

    To reach our first objective, we use Global Helioseismology (analysis of the solar oscillation eigenmodes) and Local Helioseismology (that uses travel waves). Solar seismology allows to accurately infer information about the internal structure and dynamics of the Sun,. This project covers the various necessary aspects to attain the aforementioned objectives: instrumental, observational, reduction, analysis and interpretation of data and, finally, theoretical developments of inversion techniques and development of structure and evolution models.

    On the other hand, the Astroseismology aims to obtain a similar knowledge of other stars. Thanks to the huge number of stars observed by CoRoT, Kepler and TESS space missions it is possible to extract seismic global parameters of hundreds of stars; both solar type and red giants. Furthermore, the recent deployment and beginning of observations with the high precision spectrographs of the SONG (Stellar Observations Network Group) ground-based telescopes will substantially improve the characterization of the eigenmodes spectrum in bright stars.

    The strategy of using planetary transits to discover new planets around other stars consists of the photometric detection of the dimming of the light of the star when one of its planets passes, or ‘transits’ in front of it. Currently this method is the preferred one for the study of small planets, not only due to its sensitivity, but also because this method allows a more detailed investigation of the planets found (e.g. Planetary atmospheres). This technique is similar to the one that is used for helio- and asteroseismology and so some of its methods are a logical extension from that. However, it is also important to develop new algorithms and observing methods for the unequivocal detection and analysis of planets and to be able to distinguish them from false alarms.

    The current horizon for studies of exoplanets with space missions involves new missions, beginning with the launch of CHEOPS, followed by TESS, JWST and in 2026, PLATO. Thus, there is presently a window of opportunity for ground-based facilities, and we are pursuing observations using mainly TNG, NOT y GTC.

    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

    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
    Rotation and magnetism of Kepler pulsating solar-like stars. Towards asteroseismically calibrated age-rotation relations 2014A&A...572A..34G
    Reconstruction of global solar radiation time series from 1933 to 2013 at the Izaña Atmospheric Observatory 2014AMT.....7.3139G
    CoRoT-22 b: a validated 4.9 R⊕ exoplanet in 10-d orbit 2014MNRAS.444.2783M
    Revisiting the transits of CoRoT-7b at a lower activity level 2014A&A...569A..74B
    Investigating magnetic activity of F stars with the Kepler mission 2014IAUS..302..222M
    Transiting exoplanets from the CoRoT space mission. XXVI. CoRoT-24: a transiting multiplanet system 2014A&A...567A.112A
    Impact on asteroseismic analyses of regular gaps in Kepler data 2014A&A...568A..10G