Start year
2000
Organizational Unit
Organizing institutions
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.
Members
Principal investigator
Savita
Mathur
Project staff
Juan Antonio
Belmonte Avilés
Hans Jörg
Deeg Deeg
Roi
Alonso Sobrino
Pere Lluís
Pallé Manzano
Fernando
Pérez Hernández
Teodoro
Roca Cortés
Savita
Mathur
Antonio
Jiménez Mancebo
Collaborators
Dr.
A. Eff-Darwich
Dr.
R. García
Dr.
Mads F. Anderson
Dr.
J. Christensen Dalsgaard
Dr.
F. Grundahl
Dr.
H. Kjeldsen
Dr.
Enrico Corsaro
Dr.
M. Cunha
Dr.
G. Davies
Dr.
T. Metcalfe
Dr.
T. Bedding
Dr.
D. Chou
Dr.
J. Fernández
Dr.
F. Hill
Dr.
S. Korzennik
Dr.
M. Deleuil
Dr.
D. Gandolfi
Dr.
M. Fridlund
Dr.
L. Doyle
Dr.
H. Rauer
Dr.
V. Kozhevnikov
Dr.
A. Hatzes
Dr.
T. Mazeh
Dr.
D. Queloz
Dr.
J. Ballot
Dr.
O. Creevey
Dr.
T. Boyajian
Results
Milestones
- 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.
- 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.
- 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).
- 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
- 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.
Scientific activity
Related publications
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Unusual high-frequency oscillations in the Kepler δ Scuti star KIC 4840675We show that the star KIC 4840675 observed by Kepler is composed of three stars with a rapidly rotating A-type star and two solar-type fainter companions. The A-type star is a δ Scuti variable with a dominant mode and many other modes of lower amplitude, including several low-frequency variations. The low-frequency variation with highest amplitudeBalona, L. A. et al.
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82012 -
The γ Doradus CoRoT target HD 49434. I. Results from the ground-based campaignContext: We present an extensive ground-based photometric and spectroscopic campaign of the γ Dor CoRoT target HD 49434. This campaign was a preparatory step of the CoRoT satellite observations, which occurred between October 2007 and March 2008. Aims: With satellite data, detection of low-degree pulsation modes only is achievable, and, as noUytterhoeven, K. et al.
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102008 -
The Kepler characterization of the variability among A- and F-type stars. I. General overviewContext. The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. Aims: We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and observationally investigateUytterhoeven, K. et al.
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102011 -
The excitation of solar-like oscillations in a δSct star by efficient envelope convectionDelta Scuti (δSct) stars are opacity-driven pulsators with masses of 1.5-2.5Msolar, their pulsations resulting from the varying ionization of helium. In less massive stars such as the Sun, convection transports mass and energy through the outer 30per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar exampleAntoci, V. et al.
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92011 -
Photometric multi-site campaign on massive B stars in the open cluster χ Persei (NGC 884)In 2005 a photometric observation campaign started on the open cluster χ Persei, involving 13 telescopes spread over the whole northern hemisphere. After two years we gathered almost 1200 hours of data. We present here preliminary results on the variability search, especially from the 60-cm telescope in Bialków (Poland), which show seven confirmedSaesen, S. et al.
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102008 -
Looking for a Connection between the Am Phenomenon and Hybrid δ Sct -γ Dor Pulsation: Determination of the Fundamental Parameters and Abundances of HD 114839 and BD +18 4914δ Sct-γ Dor hybrids pulsate simultaneously in p- and g-modes, which carry information on the structure of the envelope as well as to the core. Hence, they are key objects for investigating A and F type stars with asteroseismic techniques. An important requirement for seismic modeling is small errors in temperature, gravity, and chemical compositionHareter, M. et al.
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122011 -
Ground-based observations of the β Cephei CoRoT main target HD 180 642: abundance analysis and mode identificationThe known β Cephei star HD 180 642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional constraints for forthcoming asteroseismic modeling of the target. Our results are based onBriquet, M. et al.
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102009 -
Ground-based observations of the beta Cephei CoRoT main target HD 180642We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD~180642. Besides the non-linear dominant radial mode several low-amplitude modes are detected in both kinds of datasets. Our aim is to derive the wavenumbers (ℓ,m) of these modes, asBriquet, M. et al.
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72009 -
Ground-based observations of O and B starsGround-based observations are a strong tool for asteroseismic studies and even in the era of asteroseismic space missions they continue to play an important role. I will report on the activities of the CoRoT/SWG Ground-Based Observations Working Group, discuss the observational efforts of the Open Cluster campaigns and the search for the origin ofUytterhoeven, K.
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72009 -
Close-up of primary and secondary asteroseismic CoRoT targets and the ground-based follow-up observationsTo optimise the science results of the asteroseismic part of the CoRoT satellite mission a complementary simultaneous ground-based observational campaign is organised for selected CoRoT targets. The observations include both high-resolution spectroscopic and multicolour photometric data. We present the preliminary results of the analysis of theUytterhoeven, K. et al.
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102008 -
An asteroseismic study of the β Cephei star 12 Lacertae: multisite spectroscopic observations, mode identification and seismic modellingWe present the results of a spectroscopic multisite campaign for the β Cephei star 12 (DD) Lacertae. Our study is based on more than thousand high-resolution high S/N spectra gathered with eight different telescopes in a time span of 11 months. In addition, we make use of numerous archival spectroscopic measurements. We confirm 10 independentDesmet, M. et al.
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72009 -
A multisite photometric study of two unusual β Cep stars: the magnetic V2052 Oph and the massive rapid rotator V986 OphWe report a multisite photometric campaign for the β Cep stars V2052 Oph and V986 Oph. 670 h of high-quality differential photoelectric Strömgren, Johnson and Geneva time-series photometry was obtained with eight telescopes on five continents during 182 nights. Frequency analyses of the V2052 Oph data enabled the detection of three pulsationHandler, G. et al.
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82012 -
The Lupus Transit Survey for Hot Jupiters: Results and LessonsWe present the results of a deep, wide-field transit survey targeting "Hot Jupiter" planets in the Lupus region of the Galactic plane conducted over 53 nights concentrated in two epochs separated by a year. Using the Australian National University 40-inch telescope at Siding Spring Observatory (SSO), the survey covered a 0.66 deg2 region close toBayliss, Daniel D. R. et al.
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52009 -
Searching for transits in data with long time baselines and poor samplingAims: The standard method of searching parameter space for transits is ill-suited to data sets with long time baselines and poor temporal coverage, such as that anticipated from Gaia. In this paper, we present an alternative method for identifying transit candidates is such data, one focusing on finding periodicity in high S/N outliers. Methods: WeTingley, B.
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52011 -
Verification of the Kepler Input Catalog from Asteroseismology of Solar-type StarsWe calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sampleVerner, G. A. et al.
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92011 -
Unveiling stellar magnetic activity using CoRoT seismic observationsIt is well known that in the Sun, the frequencies and amplitudes of acoustic modes vary throughout the solar cycle. Indeed, while the magnetic activity goes towards its maximum, the frequencies of the modes increase and their amplitudes decrease. We have analyzed data from the CoRoT mission on a few stars that exhibit solar-like oscillations. TheMathur, Savita et al.
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12011 -
The solar-like CoRoT target HD 170987: spectroscopic and seismic observationsContext. The CoRoT mission is in its third year of observation and the data from the second long run in the galactic centre direction are being analysed. The solar-like oscillating stars that have been observed up to now have given some interesting results, specially concerning the amplitudes that are lower than predicted. We present here theMathur, S. et al.
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72010 -
The CoRoT target HD 175726: an active star with weak solar-like oscillationsContext: The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD 175726 that lasted for 27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due toMosser, B. et al.
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102009 -
solarFLAG hare and hounds: estimation of p-mode frequencies from Sun-as-star helioseismology dataWe report on the results of the latest solarFLAG hare-and-hounds exercise, which was concerned with testing methods for extraction of frequencies of low-degree solar p modes from data collected by Sun-as-a-star observations. We have used the new solarFLAG simulator, which includes the effects of correlated mode excitation and correlations withJiménez-Reyes, S. J. et al.
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102008 -
Solar-like oscillations in red giants observed with Kepler: comparison of global oscillation parameters from different methodsContext. The large number of stars for which uninterrupted high-precision photometric timeseries data are being collected with Kepler and CoRoT initiated the development of automated methods to analyse the stochastically excited oscillations in main-sequence, subgiant and red-giant stars. Aims: We investigate the differences in results for globalHekker, S. et al.
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12011
