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

    Removing systematics from the CoRoT light curves. I. Magnitude-dependent zero point 2009A&A...506..431M
    Rate and nature of false positives in the CoRoT exoplanet search 2009A&A...506..337A
    Possible detection of phase changes from the non-transiting planet HD 46375b by CoRoT 2010A&A...518L.153G
    Planetary transit candidates in the CoRoT-SRc01 field 2012A&A...539A..14E
    Planetary transit candidates in the CoRoT LRa01 field 2012A&A...538A.112C
    Planetary transit candidates in the CoRoT initial run: resolving their nature 2009A&A...506..321M
    Planetary transit candidates in CoRoT-LRc01 field 2009A&A...506..501C
    Planetary transit candidates in Corot-IRa01 field 2009A&A...506..491C
    Noise properties of the CoRoT data. A planet-finding perspective 2009A&A...506..425A
    Ground-based photometry of space-based transit detections: photometric follow-up of the CoRoT  mission 2009A&A...506..343D
    Ground-based Near-infrared Observations of the Secondary Eclipse of CoRoT-2b 2010AJ....139.1481A
    Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis 2008A&A...480..563D
    Exoplanet discoveries with the CoRoT space observatory 2010SoSyR..44..520L
    Exo-Dat: An Information System in Support of the CoRoT/Exoplanet Science 2009AJ....138..649D
    CoRoT LRa02_E2_0121: Neptune-size planet candidate turns into a hierarchical triple system with a giant primary 2011A&A...534A..67T
    A transiting giant planet with a temperature between 250K and 430K 2010Natur.464..384D
    CoRoT Measures Solar-Like Oscillations and Granulation in Stars Hotter Than the Sun 2008Sci...322..558M
    Preliminary results on the contribution of the convection motions to the Doppler velocity signal 2008JPhCS.118a2089S
    Infrared astronomical characteristics of the Roque de los Muchachos Observatory: precipitable water vapour statistics 2010MNRAS.405.2683G
    Ground-based Multisite Observations of Two Transits of HD 80606b 2010ApJ...722..880S
    Limits to the planet candidate GJ 436c 2008A&A...487L...5A
    TrES-5: A Massive Jupiter-sized Planet Transiting a Cool G Dwarf 2011ApJ...741..114M
    Transit timing analysis of the exoplanets TrES-1 and TrES-2 2009A&A...508.1011R
    SYMPA, a dedicated instrument for Jovian seismology. II. Real performance and first results 2008A&A...490..859G
    Detection of transit timing variations in excess of one hour in the Kepler multi-planet candidate system KOI 806 with the GTC 2011A&A...536L...9T
    Constraints of a pulsation frequency on stellar parameters in the eclipsing spectroscopic binary system V577 Oph 2010AN....331..952C
    Constraining the Properties of Delta Scuti Stars Using Spectroscopic Eclipsing Binary Systems 2011ApJ...733...38C
    An eclipsing post-common-envelope binary in the field of the Kepler mission 2012MNRAS.420.3017A
    A New Spectroscopic and Photometric Analysis of the Transiting Planet Systems TrES-3 and TrES-4 2009ApJ...691.1145S
    A cool starspot or a second transiting planet in the TrES-1 system? 2009A&A...494..391R

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