General
Los objetivos genéricos de este Proyecto son: 1) el estudio de la estructura y dinámica del interior solar, 2) la extensión de dicho estudio al caso de otras estrellas, 3) la búsqueda y caracterización de planetas extrasolares por métodos fotométricos (principalmente mediante el método de tránsitos) y espectroscópico (variaciones en la velocidad radial de la estrella) y 4) el análisis de las atmósferas de estos planetas.
Para el primer objetivo se utiliza la heliosismología tanto global (la que se obtiene de los modos propios de oscilación) como la local (que deriva del estudio de ondas viajeras). La sismología solar permite inferir de modo preciso información acerca de la estructura y dinámicas internas del Sol. El presente proyecto cubre las distintas facetas necesarias para alcanzar dicho objetivo, desde la instrumental, pasando por la observacional, técnicas de reducción, análisis e interpretación de los datos, así como el desarrollo de técnicas teóricas de inversión y elaboración de modelos de estructura y evolución.
Por otro lado, la astrosismología pretende obtener un conocimiento similar en otras estrellas. Hoy en día esta rama de la astrofísica está produciendo un gran número de resultados gracias a la enorme cantidad de estrellas observadas por las misiones espaciales CoRoT, Kepler y TESS, siendo posible extraer información sobre la estructura y dinámica de cientos de estrellas, tanto de tipo solar como de gigantes rojas. Todo ello se verá complementado con el desarrollo de la red SONG (Stellar Observations Network Group), una batería de telescopio en Tierra dotados con espectrógrafos.
La estrategia de utilización de tránsitos planetarios para descubrir la existencia de planetas alrededor de otras estrellas, consiste en la detección fotométrica de disminuciones de brillo de una estrella cuando uno de sus planetas está pasando entre ella y el observador. Actualmente esta metodología es la preferida para la investigación de planetas pequeños, no sólo por su sensibilidad sino también porque permite llevar a cabo estudios relativamente detallados de los planetas descubiertos. Esta tecnología es similar a la que se utiliza en helio y astrosismología por lo que se puede entender como una extensión lógica de lo aprendido con los anteriores objetivos. Por otro lado, es importante desarrollar algoritmos y métodos observacionales para la detección inequívoca y el análisis de los planetas, distinguiéndolos de los que resultan ser falsas alarmas.
El panorama actual para los estudios de exoplanetas involucra nuevas misiones espaciales como CHEOPS y TESS que serán seguidos por JWST y en 2026, PLATO. Por lo tanto, se abre una ventana temporal en la que los observatorios terrestres pueden complementar estos datos. Para ello seguimos llevando a cabo observaciones usando principalmente TNG, NOT, GTC.
Members
Results
- Miembros del grupo (P. G. Beck, H. Deeg, S. Mathur, F. Pérez, C. Régulo) estuvieron involucrados en el descubrimiento y caracterización de un "Saturno caliente" que hospeda la estrella HD 89345 observada con la misión K2 y confirmada con medidas de VR. El análisis sísmico permitió obtener estimaciones precisas de los parámetros estelares.
- P.G.Beck dirigió dos artículos sobre binarias con gigantes rojas, usando técnicas astrosimológicas para mejorar la comprensión de su estructura y efectos de marea. También se estudio la mezcla de material en su interior midiendo abundancias de Litio.
- S. Mathur participó en el análisis del primer planeta descubierto por la misión TESS, que orbita la estrella Pi Men. El análisis sísmico condujo a una detección marginal pero dió una pista del potencial uso de la astrosismología con TESS (Gandolfi et al. 2018).
- Proyecto "Solar-SONG". Por vez primera se ha utilizado instrumentación estelar (espectrógrafo SONG) para obtener medidas precisas de la velocidad radial del Sol con alta cadencia temporal (4 s.) y duración suficiente (57 días consecutivos) como para permitir el estudio detallado del espectro de oscilaciones (modos-p) y obtener sus parámetros globales
- Los investigadores Hans J. Deeg y Juan Antonio Belmonte coordinaron la edición del libro "Handbook of Exoplanets" con 160 artículos y la participación de más de 300 especialistas. Tres años de trabajo resultaron en una colección completa y actualizada del estudio de los planetas más allá del sistema solar.
Scientific activity
Publicaciones relacionadas
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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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