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. Members of the team (P. G. Beck, H. Deeg, S. Mathur, F. H. Perez, C. Regulo) were involved in the discovery and characterization of a warm Saturn transiting a slightly evolved solar-like star (HD 89345) observed with the NASA K2 mission and confirmed with RV measurements. The seismic analysis of the star led to precise estimates of the stellar parameters.
    2. P.G.Beck lead two papers on binary systems hosting red-giant binaries, using asteroseismic techniques and data from the Kepler space telescope. Beck et al (2018a,b) allow a better understanding of the stellar structure of the stellar components, and the tidal interaction in binary systems. The internal mixing was investigated through measurements lithium.
    3. S. Mathur participated in the analysis of the first planet discovered with the NASA TESS mission, orbiting the star Pi Men. The seismic analysis led to a very marginal detection but gave a hint of the asteroseismic potential with the TESS data (Gandolfi et al. 2018).
    4. Project "Solar-SONG". For the first time, stellar instrumentation (SONG spectrograph) has been used to obtain precise measurements of the radial velocity of the Sun with high temporal cadence (4 sec.) and long duration (57 consecutive days) to allow the detailed study of the spectrum of oscillations ( p-modes) and obtain their global parameters
    5. The researchers Hans J. Deeg and Juan Antonio Belmonte coordinated the edition of the "Handbook of Exoplanets", four volumes with 160 articles by more than 300 specialists in exoplanetology. Three years of intensive work have resulted in a complete documentation on the state of the art of the studies of the planets beyond the Solar System.

    Related publications

    • HD 144548: A young triply eclipsing system in the Upper Scorpius OB association
      The star HD 144548 (=HIP 78977; TYP 6212-1273-1) has been known as a detached eclipsing binary and a bona-fide member of the Upper Scorpius OB association. Continuous photometry from the K2 mission on Campaign Two has revealed the presence of additional eclipses due to the presence of a third star in the system. These are explained by a system
      Alonso, R. et al.

      Advertised on:

      12
      2015
      Citations
      32
    • Analysis of the acoustic cut-off frequency and high-frequency peaks in six Kepler stars with stochastically excited pulsations
      Gravito-acoustic modes in the Sun and other stars propagate in resonant cavities with a frequency below a given limit known as the cut-off frequency. At higher frequencies, waves are no longer trapped in the stellar interior and become traveller waves. In this article, we study six pulsating solar-like stars at different evolutionary stages
      Jiménez, A. et al.

      Advertised on:

      11
      2015
      Citations
      7
    • A seismic and gravitationally bound double star observed by Kepler. Implication for the presence of a convective core
      Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology. Aims: The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP 93511), for which
      Appourchaux, T. et al.

      Advertised on:

      10
      2015
      Citations
      43
    • Evidence of amplitude modulation due to resonant mode coupling in the δ Scuti star KIC 5892969. A particular or a general case?
      A study of the star KIC 5892969 observed by the Kepler satellite is presented. Its three highest amplitude modes present a strong amplitude modulation. The aim of this work is to investigate amplitude variations in this star and their possible cause. Using the 4 years-long observations available, we obtained the frequency content of the full light
      Barceló Forteza, S. et al.

      Advertised on:

      7
      2015
      Citations
      30
    • 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
      Context. We present the discovery of two transiting extrasolar planets by the satellite CoRoT. Aims: We aim at a characterization of the planetary bulk parameters, which allow us to further investigate the formation and evolution of the planetary systems and the main properties of the host stars. Methods: We used the transit light curve to
      Cabrera, J. et al.

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      7
      2015
      Citations
      16
    • Period, epoch, and prediction errors of ephemerides from continuous sets of timing measurements
      Space missions such as Kepler and CoRoT have led to large numbers of eclipse or transit measurements in nearly continuous time series. This paper shows how to obtain the period error in such measurements from a basic linear least-squares fit, and how to correctly derive the timing error in the prediction of future transit or eclipse events
      Deeg, H. J.

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      6
      2015
      Citations
      5
    • Kepler-423b: a half-Jupiter mass planet transiting a very old solar-like star
      We report the spectroscopic confirmation of the Kepler object of interest KOI-183.01 (Kepler-423b), a half-Jupiter mass planet transiting an old solar-like star every 2.7 days. Our analysis is the first to combine the full Kepler photometry (quarters 1-17) with high-precision radial velocity measurements taken with the FIES spectrograph at the
      Gandolfi, D. et al.

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      4
      2015
      Citations
      45
    • The two-colour EMCCD instrument for the Danish 1.54 m telescope and SONG
      We report on the implemented design of a two-colour instrument based on electron-multiplying CCD (EMCCD) detectors. This instrument is currently installed at the Danish 1.54 m telescope at ESO's La Silla Observatory in Chile, and will be available at the SONG (Stellar Observations Network Group) 1m telescope node at Tenerife and at other SONG nodes
      Skottfelt, J. et al.

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      2
      2015
      Citations
      45
    • Kepler-432 b: a massive warm Jupiter in a 52-day eccentric orbit transiting a giant star
      We study the Kepler object Kepler-432, an evolved star ascending the red giant branch. By deriving precise radial velocities from multi-epoch high-resolution spectra of Kepler-432 taken with the CAFE spectrograph at the 2.2 m telescope of Calar Alto Observatory and the FIES spectrograph at the Nordic Optical Telescope of Roque de Los Muchachos
      Ortiz, M. et al.

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      1
      2015
      Citations
      30
    • The PLATO 1.0 mission
      PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets
      Rauer, H. et al.

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      11
      2014
      Citations
      1000
    • Rotation and magnetism of Kepler pulsating solar-like stars. Towards asteroseismically calibrated age-rotation relations
      Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have independently measured asteroseismic ages, measurements of rotation and activity are particularly interesting in the
      García, R. A. et al.

      Advertised on:

      12
      2014
      Citations
      253
    • Reconstruction of global solar radiation time series from 1933 to 2013 at the Izaña Atmospheric Observatory
      This paper presents the reconstruction of the 80-year time series of daily global solar radiation (GSR) at the subtropical high-mountain Izaña Atmospheric Observatory (IZO) located in Tenerife (The Canary Islands, Spain). For this purpose, we combine GSR estimates from sunshine duration (SD) data using the Ångström-Prescott method over the 1933
      García, R. D. et al.

      Advertised on:

      9
      2014
      Citations
      17
    • CoRoT-22 b: a validated 4.9 R⊕ exoplanet in 10-d orbit
      The CoRoT satellite has provided high-precision photometric light curves for more than 163 000 stars and found several hundreds of transiting systems compatible with a planetary scenario. If ground-based velocimetric observations are the best way to identify the actual planets among many possible configurations of eclipsing binary systems, recent
      Moutou, C. et al.

      Advertised on:

      11
      2014
      Citations
      15
    • Revisiting the transits of CoRoT-7b at a lower activity level
      The first super-Earth with measured radius discovered was CoRoT-7b and it has opened the new field of rocky exoplanet characterisation. To better understand this interesting system, new observations were taken with the CoRoT satellite. During this run 90 new transits were obtained in the imagette mode. These were analysed together with the previous
      Barros, S. C. C. et al.

      Advertised on:

      9
      2014
      Citations
      65
    • Investigating magnetic activity of F stars with the Kepler mission
      The dynamo process is believed to drive the magnetic activity of stars like the Sun that have an outer convection zone. Large spectroscopic surveys showed that there is a relation between the rotation periods and the cycle periods: the longer the rotation period is, the longer the magnetic activity cycle period will be. We present the analysis of F
      Mathur, S. et al.

      Advertised on:

      8
      2014
      Citations
      1
    • Transiting exoplanets from the CoRoT space mission. XXVI. CoRoT-24: a transiting multiplanet system
      We present the discovery of a candidate multiply transiting system, the first one found in the CoRoT mission. Two transit-like features with periods of 5.11 and 11.76 d are detected in the CoRoT light curve around a main sequence K1V star of r = 15.1. If the features are due to transiting planets around the same star, these would correspond to
      Alonso, R. et al.

      Advertised on:

      7
      2014
      Citations
      20
    • Impact on asteroseismic analyses of regular gaps in Kepler data
      Context. The NASA Kepler mission has observed more than 190 000 stars in the constellations of Cygnus and Lyra. Around 4 years of almost continuous ultra high-precision photometry have been obtained reaching a duty cycle higher than 90% for many of these stars. However, almost regular gaps due to nominal operations are present in the light curves
      García, R. A. et al.

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      8
      2014
      Citations
      119
    • The Mark-I helioseismic experiment - I. Measurements of the solar gravitational redshift (1976-2013)
      The resonant scattering solar spectrophotometer `Mark-I', designed and build at the University of Birmingham (UK) and located at the Observatorio del Teide (Spain), has been continuously in operation for the past 38 years. During this period of time, it has provided high-precision measurements of the radial velocity of the Sun as a star, which has
      Roca Cortés, T. et al.

      Advertised on:

      9
      2014
      Citations
      14
    • Confirmation of an exoplanet using the transit color signature: Kepler-418b, a blended giant planet in a multiplanet system
      Aims: We announce confirmation of Kepler-418b, one of two proposed planets in this system. This is the first confirmation of an exoplanet based primarily on the transit color signature technique. Methods: We used the Kepler public data archive combined with multicolor photometry from the Gran Telescopio de Canarias and radial velocity follow-up
      Tingley, B. et al.

      Advertised on:

      7
      2014
      Citations
      15
    • Oscillation mode linewidths and heights of 23 main-sequence stars observed by Kepler
      Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe the stars using asteroseismology. Aims: We provide the mode linewidths and mode heights of the oscillations of various stars as a function of frequency and of effective temperature. Methods: We used a time series of
      Appourchaux, T. et al.

      Advertised on:

      6
      2014
      Citations
      45

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