Pruebas Observacionales de los Procesos de Nucleosíntesis en el Universo

Año de inicio
2004
Unidad organizativa
    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.

    1. 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.
    2. 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
    3. 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]
    4. 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.

    Publicaciones relacionadas

    • A compositional link between rocky exoplanets and their host stars

      Stars and planets both form by accreting material from a surrounding disk. Because they grow from the same material, theory predicts that there should be a relationship between their compositions. In this study, we search for a compositional link between rocky exoplanets and their host stars. We estimate the iron-mass fraction of rocky exoplanets

      Adibekyan, Vardan et al.

      Fecha de publicación:

      10
      2021
    • The CARMENES search for exoplanets around M dwarfs. Stellar atmospheric parameters of target stars with SteParSyn

      We determined effective temperatures, surface gravities, and metallicities for a sample of 343 M dwarfs observed with CARMENES, the double-channel, high-resolution spectrograph installed at the 3.5 m telescope at Calar Alto Observatory. We employed SteParSyn, a Bayesian spectral synthesis implementation particularly designed to infer the stellar

      Marfil, E. et al.

      Fecha de publicación:

      12
      2021
    • Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. IV. Carbon and C/O ratios for Galactic stellar populations and planet hosts

      Context. To understand the formation and composition of planetary systems, it is essential to have insights into the chemical composition of their host stars. In particular, C/O elemental ratios are useful for constraining the density and bulk composition of terrestrial planets. Aims: We study the carbon abundances with a twofold objective. On the

      Delgado Mena, E. et al.

      Fecha de publicación:

      11
      2021
    • SWEET-Cat 2.0: The Cat just got SWEETer. Higher quality spectra and precise parallaxes from Gaia eDR3

      Aims: The catalog of Stars With ExoplanETs (SWEET-Cat) was originally introduced in 2013. Since then many more exoplanets have been confirmed, increasing significantly the number of host stars listed there. A crucial step toward a comprehensive understanding of these new worlds is the precise and homogeneous characterization of their host stars

      Sousa, S. G. et al.

      Fecha de publicación:

      12
      2021
    • Hubble spectroscopy of LB-1: Comparison with B+black-hole and Be+stripped-star models

      Context. LB-1 (alias ALS 8775) has been proposed as either an X-ray dim B-type star plus black hole (B+BH) binary or a Be star plus an inflated stripped star (Be+Bstr) binary. The latter hypothesis contingent upon the detection and characterization of the hidden broad-lined star in a composite optical spectrum. Aims: Our study is aimed at testing

      Lennon, D. J. et al.

      Fecha de publicación:

      5
      2021
    • Stellar clustering and orbital architecture of planetary systems

      Context. Revealing the mechanisms shaping the architecture of planetary systems is crucial for our understanding of their formation and evolution. In this context, it has been recently proposed that stellar clustering might be the key in shaping the orbital architecture of exoplanets. Aims: The main goal of this work is to explore the factors that

      Adibekyan, V. et al.

      Fecha de publicación:

      5
      2021
    • The Gaia-ESO Survey: Calibrating the lithium-age relation with open clusters and associations. I. Cluster age range and initial membership selections

      Context. Previous studies of open clusters have shown that lithium depletion is not only strongly age dependent but also shows a complex pattern with other parameters that is not yet understood. For pre- and main-sequence late-type stars, these parameters include metallicity, mixing mechanisms, convection structure, rotation, and magnetic activity

      Gutiérrez Albarrán, M. L. et al.

      Fecha de publicación:

      11
      2020
    • Benchmark stars, benchmark spectrographs. Detailed spectroscopic comparison of ESPRESSO, PEPSI, and HARPS data for Gaia benchmark stars

      Context. Gaia benchmark stars are selected to be calibration stars for different spectroscopic surveys. Very high-quality and homogeneous spectroscopic data for these stars are therefore required. We collected ultrahigh-resolution ESPRESSO spectra for 30 of the 34 Gaia benchmark stars and made them public. Aims: We quantify the consistency of the

      Adibekyan, V. et al.

      Fecha de publicación:

      10
      2020
    • Phase-dependent Study of Near-infrared Disk Emission Lines in LB-1

      The mass, origin, and evolutionary stage of the binary system LB-1 have been intensely debated, following the claim that it hosts an ∼70M☉ black hole, in stark contrast with the expectations for Galactic remnants. We conducted a high-resolution, phase-resolved spectroscopic study of its Paschen lines, using the Calar Alto 3.5 m telescope. We find

      Liu, Jifeng et al.

      Fecha de publicación:

      9
      2020
    • Stellar atmospheric parameters of FGK-type stars from high-resolution optical and near-infrared CARMENES spectra

      With the purpose of assessing classic spectroscopic methods on high-resolution and high signal-to-noise ratio spectra in the near-infrared wavelength region, we selected a sample of 65 F-, G-, and K-type stars observed with CARMENES, the new, ultra-stable, double-channel spectrograph at the 3.5 m Calar Alto telescope. We computed their stellar

      Marfil, E. et al.

      Fecha de publicación:

      3
      2020
    • A detailed non-LTE analysis of LB-1: Revised parameters and surface abundances

      Context. It has recently been proposed that LB-1 is a binary system at 4 kpc consisting of a B-type star of 8 M☉ and a massive stellar black hole (BH) of 70 M☉. This finding challenges our current theories of massive star evolution and formation of BHs at solar metallicity. Aims: Our objective is to derive the effective temperature, surface gravity

      Simón-Díaz, S. et al.

      Fecha de publicación:

      2
      2020
    • STEPAR: an automatic code to infer stellar atmospheric parameters

      Context. STEPAR is an automatic code written in Python 3.X designed to compute the stellar atmospheric parameters Teff, log g, [Fe/H], and ξ of FGK-type stars by means of the equivalent width (EW) method. This code has already been extensively tested in different spectroscopic studies of FGK-type stars with several spectrographs and against

      Tabernero, H. M. et al.

      Fecha de publicación:

      8
      2019
    • Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]

      Aims: The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances. Methods: We derived different sets of ages using Padova and Yonsei-Yale isochrones and HIPPARCOS and Gaia parallaxes for a sample

      Delgado Mena, E. et al.

      Fecha de publicación:

      4
      2019
    • The metallicity-period-mass diagram of low-mass exoplanets

      The number of exoplanet detections continues to grow following the development of better instruments and missions. Key steps for the understanding of these worlds comes from their characterization and statistical studies. We explore the metallicity-period-mass diagram for known exoplanets by using an updated version of The Stellar parameters for

      Sousa, S. G. et al.

      Fecha de publicación:

      5
      2019
    • SWEET-Cat updated. New homogenous spectroscopic parameters

      Context. Exoplanets have now been proven to be very common. The number of its detections continues to grow following the development of better instruments and missions. One key step for the understanding of these worlds is their characterization, which mostly depend on their host stars. Aims: We perform a significant update of the Stars With

      Sousa, S. G. et al.

      Fecha de publicación:

      11
      2018
    • 3D non-LTE corrections for Li abundance and 6Li/7Li isotopic ratio in solar-type stars. I. Application to HD 207129 and HD 95456

      Context. 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 becomes

      Harutyunyan, G. et al.

      Fecha de publicación:

      10
      2018
    • Chemical Abundances of Neutron-capture Elements in Exoplanet-hosting Stars

      To 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). This

      Delgado Mena, E. et al.

      Fecha de publicación:

      9
      2018
    • C/O vs. Mg/Si ratios in solar type stars: The HARPS sample

      Context. 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 possible

      Suárez-Andrés, L. et al.

      Fecha de publicación:

      6
      2018
    • Constraining planet structure and composition from stellar chemistry: trends in different stellar populations

      Context. The chemical composition of stars that have orbiting planets provides important clues about the frequency, architecture, and composition of exoplanet systems. Aims: We explore the possibility that stars from different galactic populations that have different intrinsic abundance ratios may produce planets with a different overall

      Santos, N. C. et al.

      Fecha de publicación:

      12
      2017
    • MASTER Optical Detection of the First LIGO/Virgo Neutron Star Binary Merger GW170817

      Following 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, which

      Lipunov, V. M. et al.

      Fecha de publicación:

      11
      2017

    Charlas relacionadas

    No se han encontrado charlas relacionadas.

    Congresos relacionados

    No se han encontrado congresos relacionados.