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

    Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission 2011Sci...332..213C
    Effect of line-of-sight inclinations on the observation of solar activity cycle: Lessons for CoRoT & Kepler 2011JPhCS.271a2056V
    Determining global parameters of the oscillations of solar-like stars 2010A&A...511A..46M
    Detection of Solar-like Oscillations from Kepler Photometry of the Open Cluster NGC 6819 2010ApJ...713L.182S
    CoRoT sounds the stars: p-mode parameters of Sun-like oscillations on HD 49933 2008A&A...488..705A
    CoRoT Reveals a Magnetic Activity Cycle in a Sun-Like Star 2010Sci...329.1032G
    Calibrating Convective Properties of Solar-like Stars in the Kepler Field of View 2012ApJ...755L..12B
    Asteroseismology of the Solar Analogs 16 Cyg A and B from Kepler Observations 2012ApJ...748L..10M
    Asteroseismology of solar-type stars with Kepler I: Data analysis 2010AN....331..972K
    Asteroseismology from multi-month Kepler photometry: the evolved Sun-like stars KIC 10273246 and KIC 10920273 2011A&A...534A...6C
    Asteroseismic Diagrams from a Survey of Solar-like Oscillations with Kepler 2011ApJ...742L...3W
    AsteroFLAG: First results from hare-and-hounds Exercise #1 2008AN....329..549C
    AsteroFLAG — from the Sun to the stars 2008JPhCS.118a2048C
    Accurate p-mode measurements of the G0V metal-rich CoRoT target HD 52265 2011A&A...530A..97B
    Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets 2012MNRAS.423..122B
    About the p-mode frequency shifts in HD 49933 2011A&A...530A.127S
    A Uniform Asteroseismic Analysis of 22 Solar-type Stars Observed by Kepler 2012ApJ...749..152M
    A Precise Asteroseismic Age and Radius for the Evolved Sun-like Star KIC 11026764 2010ApJ...723.1583M
    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

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