Navegação Ciências Exatas e da Terra por Autor "Dreizler, Stefan"
Resultados 1-14 de 14
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Outliers : multicolour photometry guiding the search for evolved binary systems in the globular cluster 47Tucanae
(2018) [Artigo de periódico]We use Hubble Space Telescope multicolour photometry of the globular cluster 47 Tucanae to uncover a population of 24 objects with no previous classification that are outliers from the single-star model tracks in the ... -
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 everchanging pulsating white dwarf GD358
(2003) [Artigo de periódico]We report 323 hours of nearly uninterrupted time series photometric observations of the DBV star GD 358 acquired with the Whole Earth Telescope (WET) during May 23rd to June 8th, 2000. We acquired more than 232 000 independent ... -
The pulsation modes of the pre-white dwarf PG 1159-035
(2008) [Artigo de periódico]Context. 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 ... -
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 ... -
A Whole Earth Telescope campaign on the pulsating subdwarf B binary system PG 1336-018 (NY Vir)
(2003) [Artigo de periódico]We present results from a multisite (‘Whole Earth Telescope’) photometric campaign on PG 1336−018, the close eclipsing binary system containing a pulsating subdwarf B (sdB) star. The main part of the campaign (1999 April) ... -
Whole Earth Telescope observations of BPM 37093 : a seismological test of crystallization theory in white dwarfs
(2005) [Artigo de periódico]BPM 37093 is the only hydrogen-atmosphere white dwarf currently known which has sufficient mass (~1.1 Mʘ) to theoretically crystallize while still inside the ZZ Ceti instability strip (Teff ~ 12 000 K). As a consequence, ...
