Año de inicio
2004
Unidad organizativa
Institución organizadora
Subvenciones relacionadas:
General
Descripción
Recientemente se han llevado a cabo varios análisis espectroscópicos de estrellas con planetas. Uno de los resultados más relevantes ha sido descubrir que las estrellas con planetas son en promedio más metálicas que las estrellas del mismo tipo espectral sin planetas conocidos (Santos, Israelian & Mayor 2001, A&A, 373, 1019; 2004, A&A, 415, 1153). Existen dos hipótesis posibles para relacionar el exceso de metalicidad con la presencia de planetas. La primera es la del “autoenriquecimiento” que atribuye el origen de la sobreabundancia de metales observada en estrellas con planetas a la acreción sobre la estrella madre de grandes cantidades de material planetario rocoso, rico en metales y pobre en elementos como H y He. La hipótesis contraria es la principal y considera que el exceso de metales sea debido al alto contenido en metales de la nube protoplanetaria a partir de la cual se formó el sistema estrella-planeta.
Los elementos ligeros pueden proporcionar información valiosa sobre la mezcla, la difusión y la evolución del momento angular en estrellas con planetas, así como sobre la actividad estelar causada por la interacción con exoplanetas (Santos, Israelian, García López et al. 2004, A&A, 427, 1085; Israelian et al. 2004, A&A, 414, 601). Estudios sobre el berilio, el litio y la razón isotópica 6Li/7Li podrían aportar pruebas para distinguir entre las diferentes teorías de formación planetaria (Sandquist et al. 2002, ApJ, 572, 1012). Israelian et al. encontraron evidencias de la caída de un planeta o de material protoplanetario sobre la estrella HD82943 (2001, Nature, 411, 163; 2003, A&A, 405, 753).
Si el “autoenriquecimiento” fuera el principal responsable del exceso de metalicidad de las estrellas con planetas, eso implicaría una sobreabundancia relativa de elementos refractarios (Si, Mg, Ca, Ti, etc.) respecto a los volátiles (CNO, S y Zn). Se han llevado a cabo varios estudios espectroscópicos del hierro (Santos et al. 2001, A&A, 373, 1019; 2003, A&A, 398, 363; 2004, A&A, 415, 1153) y de otros elementos (Bodaghee et al 2003, A&A, 404, 715; Ecuvillon, Israelian, Santos et al. 2004, A&A, 418, 703; 2004, A&A, 426, 619; 2006, A&A, 445,633; 2006, A&A, 449, 809; Gilli, Israelian, Ecuvillon, et al. 2006, A&A, 449,723).
El análisis espectroscópico de estrellas ricas en metales también proporciona información valiosa sobre las tasas de eyección al medio interestelar de elementos químicos producidos por explosiones de supernova en los últimos 10 mil millones de años. Otro método alternativo para investigar los productos de las explosiones de supernova es el estudio de las estrellas compañeras de los sistemas binarios de rayos X.
Miembros
Investigador principal
Garik
Israelian
Colaboradores
Dr.
M. Mayor
Dr.
N. Santos
Dr.
S. Sousa
Dr.
Elisa Delgado
Dr.
Vardan Adibekyan
Dr.
Cladimir Lipunov
Dr.
Michael Frolov
Dr.
Robin Rees
Resultados
- La correlación planeta-metalicidad se revisa y muestra que la distribución de metalicidad de las estrellas que albergan planetas de baja masa (por debajo de 30 M⊕) es indistinguible de la de la muestra de vecindario solar en términos de distribución de metalicidad.
- Encontramos que las correcciones 3D 6Li / 7Li son siempre negativas, lo que demuestra que el análisis 1D LTE puede sobreestimar significativamente la presencia de 6Li (hasta 4.9% puntos) en las atmósferas de estrellas enanas de tipo solar. Aunque la síntesis espectral NLTE 3D implica un esfuerzo computacional extenso, los resultados pueden hacerse accesibles con herra
- Hemos analizado el comportamiento de las abundancias químicas de Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd y Eu en la muestra de búsqueda de planetas HARPS-GTO grande y homogénea. Comparamos las relaciones [X / Fe] de tales Elementos en diferentes bandejas de metalicidad y encontramos que los anfitriones de los planetas presentan mayores abundancias de Zn para [Fe / H]
- Encontramos que el 100% de la muestra planetaria en HARPS-GTO presenta C / O> 0,4, mientras que el 14% presenta valores de C / O inferiores a 0,4. Con respecto al Mg / Si, todas las estrellas con compañero planetario de baja masa mostraron valores entre uno y dos.
Actividad científica
Publicaciones relacionadas
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3D non-LTE corrections for Li abundance and 6Li/7Li isotopic ratio in solar-type stars. I. Application to HD 207129 and HD 95456Context. Convective motions in solar-type stellar atmospheres induce Doppler shifts that affect the strengths and shapes of spectral absorption lines and create slightly asymmetric line profiles. One-dimensional (1D) local thermodynamic equilibrium (LTE) studies of elemental abundances are not able to reproduce this phenomenon, which becomesHarutyunyan, G. et al.
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Chemical Abundances of Neutron-capture Elements in Exoplanet-hosting StarsTo understand the formation and composition of planetary systems it is important to study their host stars composition since both are formed in the same stellar nebula. In this work, we analyze the behaviour of chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu in the large and homogeneous HARPS-GTO planet search sample (R ˜ 115000). ThisDelgado Mena, E. et al.
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C/O vs. Mg/Si ratios in solar type stars: The HARPS sampleContext. Aims: We aim to present a detailed study of the magnesium-to-silicon and carbon-to-oxygen ratios (Mg/Si and C/O) and their importance in determining the mineralogy of planetary companions. Methods: Using 499 solar-like stars from the HARPS sample, we determined C/O and Mg/Si elemental abundance ratios to study the nature of the possibleSuárez-Andrés, L. et al.
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MASTER Optical Detection of the First LIGO/Virgo Neutron Star Binary Merger GW170817Following the discovery of the gravitational-wave source GW170817 by three Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo antennae (Abbott et al., 2017a), the MASTER Global Robotic Net telescopes obtained the first image of the NGC 4993 host galaxy. An optical transient, MASTER OTJ130948.10-232253.3/SSS17a was later found, whichLipunov, V. M. et al.
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Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. II. Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and EuAims: To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. The aim of this work is to explore the chemical abundances of neutron capture elements which are a product of different nucleosynthesis processesDelgado Mena, E. et al.
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102017 -
CNO behaviour in planet-harbouring stars. II. Carbon abundances in stars with and without planets using the CH bandContext. Carbon, oxygen and nitrogen (CNO) are key elements in stellar formation and evolution, and their abundances should also have a significant impact on planetary formation and evolution. Aims: We aim to present a detailed spectroscopic analysis of 1110 solar-type stars, 143 of which are known to have planetary companions. We have determinedSuárez-Andrés, L. et al.
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32017 -
First gravitational-wave burst GW150914: MASTER optical follow-up observationsThe Advanced LIGO observatory recently reported the first direct detection of the gravitational waves (GWs) predicted by Einstein & Sitzungsber. We report on the first optical observations of the GW source GW150914 error region with the Global MASTER Robotic Net. Between the optical telescopes of electromagnetic support, the covered area isLipunov, V. M. et al.
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32017 -
The EChO science caseThe discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune—all unknown in the Solar System. Observations to date have shown thatTinetti, Giovanna et al.
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122015 -
Identifying the best iron-peak and α-capture elements for chemical tagging: The impact of the number of lines on measured scatterAims: The main goal of this work is to explore which elements carry the most information about the birth origin of stars and, as such, which are best suited for chemical tagging. Methods: We explored different techniques to minimize the effect of outlier value lines in the abundances by using Ni abundances derived for 1111 FGK-type stars. WeAdibekyan, V. et al.
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112015 -
From stellar to planetary composition: Galactic chemical evolution of Mg/Si mineralogical ratioAims: The main goal of this work is to study element ratios that are important for the formation of planets of different masses. Methods: We study potential correlations between the existence of planetary companions and the relative elemental abundances of their host stars. We use a large sample of FGK-type dwarf stars for which precise Mg, Si, andAdibekyan, V. et al.
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92015 -
ARES v2: new features and improved performanceAims: We present a new upgraded version of ARES. The new version includes a series of interesting new features such as automatic radial velocity correction, a fully automatic continuum determination, and an estimation of the errors for the equivalent widths. Methods: The automatic correction of the radial velocity is achieved with a simple crossSousa, S. G. et al.
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52015 -
Chemical abundances and kinematics of 257 G-, K-type field giants. Setting a base for further analysis of giant-planet properties orbiting evolved starsWe performed a uniform and detailed abundance analysis of 12 refractory elements (Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Co, Sc, Mn, and V) for a sample of 257 G- and K-type evolved stars from the CORALIE planet search programme. To date, only one of these stars is known to harbour a planetary companion. We aimed to characterize this large sample ofAdibekyan, V. Zh. et al.
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62015 -
Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere . The impact on stellar and planetary massAims: In this work we derive new precise and homogeneous parameters for 37 stars with planets. For this purpose, we analyze high resolution spectra obtained by the NARVAL spectrograph for a sample composed of bright planet host stars in the northern hemisphere. The new parameters are included in the SWEET-Cat online catalogue. Methods: To ensureSousa, S. G. et al.
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Li abundances in F stars: planets, rotation, and Galactic evolutionAims: We aim, on the one hand, to study the possible differences of Li abundances between planet hosts and stars without detected planets at effective temperatures hotter than the Sun, and on the other hand, to explore the Li dip and the evolution of Li at high metallicities. Methods: We present lithium abundances for 353 main sequence stars withDelgado Mena, E. et al.
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Determination of the spectroscopic stellar parameters for 257 field giant stars★The study of stellar parameters of planet-hosting stars, such as metallicity and chemical abundances, help us to understand the theory of planet formation and stellar evolution. Here, we present a catalogue of accurate stellar atmospheric parameters and iron abundances for a sample of 257 K and G field evolved stars that are being surveyed forAlves, S. et al.
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