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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p-mode power variation with solar atmosphere as observed in the Na D1 and K spectral linesIn this work we investigate p-mode power variation with solar atmosphere. To this aim, we use THÉMIS observations of the Na D1 (λ5896 Å) and K (λ7699 Å) spectral lines. While the formation heights of the K spectral line are essentially located in the photospheric layer, the formation heights of the Na D1 line span a much wider region: fromSimoniello, R. et al.
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62008 -
HELAS IT-platform: A new tool for the European Helio- and Asteroseismology community.HELAS is a Coordination Action funded under the European Commission's Sixth Framework Programme (FP6) since April 1st, 2006 till March 31st, 2010. The HELAS Consortium includes 10 partner institutions that host researchers active in helio- and asteroseismology. This initiative offers a unique chance to advance the field further by coordinating theJiménez-Reyes, S. J. et al.
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42008 -
The pulsation modes of the pre-white dwarf PG 1159-035Context: PG 1159-035, a pre-white dwarf with Teff≃ 140 000 K, is the prototype of both two classes: the PG 1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope (WET) showed a rich frequency spectrum allowing the identification of 122 pulsation modes. AnalyzingCosta, J. E. S. et al.
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12008 -
The pulsating hot subdwarf Balloon 090100001: results of the 2005 multisite campaignWe present the results of a multisite photometric campaign on the pulsating B-type hot subdwarf star Balloon090100001 (Bal09). The star is one of the two known hybrid hot subdwarfs with both long- and short-period oscillations, theoretically attributed to g and p modes. The campaign involved eight telescopes with three obtaining UBVR data, four BBaran, A. et al.
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12009 -
Testing the evolution of the DB white dwarf GD 358: first results of a new approach using asteroseismologyAims: We present a new method that investigates the evolutionary history of the pulsating DB white dwarf GD 358 using asteroseismology. This is done considering the internal C/O profile, which describes the relative abundances of carbon and oxygen from the core of the star to its surface. Different evolutionary channels lead to the generation ofGonzález Pérez, J. M. et al.
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12009 -
On the Possible Existence of Short-Period g-Mode Instabilities Powered by Nuclear-Burning Shells in Post-Asymptotic Giant Branch H-Deficient (PG1159-Type) StarsWe present a pulsational stability analysis of hot post-asymptotic giant branch (AGB) H-deficient pre-white dwarf stars with active He-burning shells. The stellar models employed are state-of-the-art equilibrium structures representative of PG1159 stars derived from the complete evolution of the progenitor stars, through the thermally pulsing AGBCórsico, A. H. et al.
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82009 -
A survey for pulsating subdwarf B stars with the Nordic Optical TelescopeContext. A search programme for pulsating subdwarf B stars was conducted with the Nordic Optical Telescope on La Palma over 59 nights between 1999 and 2009. Aims: The purpose of the programme was to significantly extend the number of rapidly pulsating sdB stars to better understand the properties of this new group of variable compact stars. MethodsØstensen, R. H. et al.
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42010 -
A peculiar Of star in the Local Group galaxy IC 1613Context. Results from the theory of radiatively driven winds are nowadays incorporated in stellar evolutionary and population synthesis models, and are used in our interpretation of the observations of the deep Universe. Yet, the theory has been confirmed only until Small Magellanic Cloud metallicities. Observations and analyses of O-stars at lowerHerrero, A. et al.
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72012 -
Update on g-mode researchSince the beginning of this century we have attended a blooming of the gravity-mode research thanks to the unprecedented quality of the data available, either from space with SoHO, or from the ground-based networks as BiSON or GONG. From the first upper limit of the gravity-mode amplitudes fixed at 10 mm/s at 200 μHz given by Appourchaux et al.García, R. A. et al.
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62008 -
The solar core as never seen beforeOne of the main drawbacks in the analysis of the dynamics of the solar core comes from the lack of consistent data sets that cover the low and intermediate degree range (ell = 1,200). It is usually necessary to merge data obtained from different instruments and/or fitting methodologies and hence one introduces undesired systematic errors. InEff-Darwich, A. et al.
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12011 -
The rotation rate and its evolution derived from improved mode fitting and inversion methodologyWe present inferences of the internal solar rotation rate and its evolution during solar cycle 23. A full solar cycle of MDI observations have been analyzed using an improved fitting methodology and using time series of various lengths, up to a single 4,608 day long epoch (64 times 72 days or 12.6 yr). We used time series of spherical harmonicKorzennik, S. G. et al.
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12011 -
Sensitivity of helioseismic gravity modes to the dynamics of the solar coreContext: The dynamics of the solar core cannot be properly constrained through the analysis of acoustic oscillation modes. Gravity modes (g modes) are necessary to understand the structure and dynamics of the deepest layers of the Sun. Through recent progress on the observation of these modes - both individually and collectively - new informationMathur, S. et al.
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62008 -
New insights on the solar coreSince the detection of the asymptotic properties of the dipole gravity modes in the Sun, the quest to find individual gravity modes has continued. An extensive and deeper analysis of 14 years of continuous GOLF/SoHO observational data, unveils the presence of a pattern of peaks that could be interpreted as individual dipole gravity modes in theGarcía, R. A. et al.
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12011 -
Influence of Low-Degree High-Order p-Mode Splittings on the Solar Rotation ProfileThe solar rotation profile is well constrained down to about 0.25 R &sun; thanks to the study of acoustic modes. Since the radius of the inner turning point of a resonant acoustic mode is inversely proportional to the ratio of its frequency to its degree, only the low-degree p modes reach the core. The higher the order of these modes, the deeperGarcía, R. A. et al.
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92008 -
HD 172189: another step in furnishing one of the best laboratories known for asteroseismic studiesHD 172189 is a spectroscopic eclipsing binary system with a rapidly-rotating pulsating δ Scuti component. It is also a member of the open cluster IC 4756. These combined characteristics make it an excellent laboratory for asteroseismic studies. To date, HD 172189 has been analysed in detail photometrically but not spectroscopically. For this reasonCreevey, O. L. et al.
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112009 -
Detection and temporal coherence of p-modes below 1.4 mHzData collected recently by the helioseismic experiments aboard the SOHO spacecraft have allowed the detection of low degree p-modes with increasingly lower order n. In particular, the GOLF experiment is currently able to unambiguously identify low degree modes with frequencies as low as 1.3 mHz. The detection of p-modes with very low frequency ({iEff-Darwich, A. et al.
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62008 -
Comparative analysis of the impact of geological activity on the structural design of telescope facilities in the Canary Islands, Hawaii and ChileAn analysis of the impact of seismic and volcanic activity has been carried out at selected astronomical sites, namely the observatories of El Teide (Tenerife, Canary Islands), Roque de los Muchachos (La Palma, Canary Islands), Mauna Kea (Hawaii) and Paranal (Chile), and the candidate site of Cerro Ventarrones (Chile). Hazard associated withEff-Darwich, A. et al.
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92010 -
Analysis of the Sensitivity of Solar Rotation to Helioseismic Data from GONG, GOLF, and MDI ObservationsAccurate determination of the rotation rate in the radiative zone of the Sun from helioseismic observations requires rotational frequency splittings of exceptional quality as well as reliable inversion techniques. Here we present inferences based on mode parameters calculated from 2088 day MDI, GONG, and GOLF time series that were fitted toEff-Darwich, A. et al.
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62008 -
Advances in solar rotation rate inferences: Unstructured grid inversions and improved rotational splittingsWe present a new inversion methodology that adapts the inversion grid in both radius and co-latitude to the data set and solves the inversion problem through an iterative procedure. This method was tested on state-of-the-art global mode frequency splittings to assess the solar interior rotation rate and its temporal variation. We also explore theEff-Darwich, A. et al.
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122010 -
Accurate Mapping of the Torsional Oscillations: a Trade-Off Study between Time Resolution and Mode Characterization PrecisionOne salient result of global helioseismology is the mapping of the so-called torsional oscillations below the solar surface. These subsurface flows are inferred by inverting rotational frequency splitting sets of global modes. These flows extend down to a depth of at least 0.8 R, and are likely associated with the activity cycle of our star. ToEff-Darwich, A. et al.
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