Navegação Ciências Exatas e da Terra por Autor "Asplund, Martin"
Resultados 1-14 de 14
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18 Sco : a solar twin rich in refractory and neutron-capture elements, implications for chemical tagging
(2014) [Artigo de periódico]We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), ... -
GRACES observations of young [α/Fe]-rich stars
(2016) [Artigo de periódico]We measure chemical abundance ratios and radial velocities in four massive (i.e. young) [α/Fe]-rich red giant stars using high-resolution high-S/N spectra from ESPaDOnS fed by Gemini-GRACES. Our differential analysis ensures ... -
Spectroscopic binaries in the Solar Twin Planet Search program : from substellar–mass to M dwarf companions
(2017) [Artigo de periódico]Previous studies on the rotation of Sun-like stars revealed that the rotational rates of young stars converge towards a well-defined evolution that follows a power-law decay. It seems, however, that some binary stars do ... -
The chemical homogeneity of sun-like stars in the solar neighborhood
(2018) [Artigo de periódico]The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate ... -
The EMBLA survey : metal-poor stars in the Galactic bulge
(2016) [Artigo de periódico]Cosmological models predict the oldest stars in theGalaxy should be found closest to the centre of the potential well, in the bulge. The Extremely Metal-poor BuLge stars with AAOmega survey (EMBLA) successfully searched ... -
The Gaia-ESO survey : radial metallicity gradients and age-metallicity relation of stars in the Milky Way disk
(2014) [Artigo de periódico]We study the relationship between age, metallicity, and α-enhancement of FGK stars in the Galactic disk. The results are based upon the analysis of high-resolution UVES spectra from the Gaia-ESO large stellar survey. We ... -
The Li–age correlation: the Sun is unusually Li deficient for its age
(2019) [Artigo de periódico]This work aims to examine in detail the depletion of lithium in solar twins to better constrain stellar evolution models and investigate its possible connection with exoplanets. We employ spectral synthesis in the region ... -
The solar twin planet search I. Fundamental parameters of the stellar sample
(2014) [Artigo de periódico]Context. We are carrying out a search for planets around a sample of solar twin stars using the HARPS spectrograph. The goal of this project is to exploit the advantage offered by solar twins to obtain chemical abundances ... -
The solar twin planet search II. A Jupiter twin around a solar twin
(2015) [Artigo de periódico]Context. With high-precision radial velocity surveys reaching a su ciently long time baseline, the domain of long-period planet detections has recently opened up. The search for Jupiter-like planets is especially important ... -
The solar twin planet search : IV. The Sun as a typical rotator and evidence for a new rotational braking law for Sun-like stars
(2016) [Artigo de periódico]Context. It is still unclear how common the Sun is when compared to other similar stars in regards to some of its physical properties, such as rotation. Considering that gyrochronology relations are widely used today to ... -
The solar twin planet search : the age-chromospheric activity relation
(2018) [Artigo de periódico]Context. It is well known that the magnetic activity of solar-type stars decreases with age, but it is widely debated in the literature whether there is a smooth decline or if there is an early sharp drop until 1–2 Gyr ... -
The solar twin planet search : V. close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
(2017) [Artigo de periódico]Context. More than two thousand exoplanets have been discovered to date. Of these, only a small fraction have been detected around solar twins, which are key stars because we can obtain accurate elemental abundances ... -
The temporal evolution of neutron-capture elements in the Galactic discs
(2018) [Artigo de periódico]Important insights into the formation and evolution of the Galactic disc(s) are contained in the chemical compositions of stars.We analysed high-resolution and high signal-to-noise HARPS spectra of 79 solar twin stars in ... -
Thorium in solar twins : implications for habitability in rocky planets
(2019) [Artigo de periódico]We have investigated the thorium (Th) abundance in a sample of 53 thin disc solar twins covering a wide range of ages. These data provide constrains on the mantle energy budget of terrestrial planets that can be formed ...
