相关论文: Chemical stratification in the atmosphere of Ap st…

In this paper we report on the real nature of the star HD 145792, classified as He weak in {\it ``The General Catalogue of Ap and Am stars''}. By means of [email protected] high resolution spectroscopic data, we refined the atmospheric…

Slow rotation and absence of strong mixing processes in atmospheres of chemically peculiar stars develop ideal conditions for the appearance of abundance anomalies through the mechanism of microscopic particle diffusion. This makes these…

Using high resolution, high-S/N archival UVES spectra, we have performed a detailed spectroscopic analysis of 4 chemically peculiar HgMn stars (HD 71066, HD 175640, HD 178065 and HD 221507). Using spectrum synthesis, mean photospheric…

In atmospheres of magnetic main-sequence stars, the diffusion of chemical elements leads to a number of observed anomalies, such as abundance spots across the stellar surface. The aim of this study was to derive a detailed picture of the…

Context: Chemically peculiar A type (Ap) stars are a subgroup of the CP2 stars which exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr and rare earth elements. The pulsating subgroup of the Ap stars, the roAp stars,…

In recent papers convincing evidence has been presented for chemical stratification in Ap star atmospheres, and surface abundance maps have been shown to correlate with the magnetic field direction. Radiatively driven diffusion in magnetic…

The Ap star HD3980 appears to be a promising roAp candidate based on its fundamental parameters, leading us to search for rapid pulsations with the VLT UV-Visual Echelle Spectrograph (UVES). A precise Hipparcos parallax and estimated…

It is commonly believed that the observed overabundances of many chemical species relative to the expected cluster metallicity in blue horizontal branch (BHB) stars appear as a result of atomic diffusion in the photosphere. The slow…

High-resolution spectra of some chemically peculiar stars clearly demonstrate the presence of strong abundance gradients in their atmospheres. However, these inhomogeneities are usually ignored in the standard scheme of model atmosphere…

Intermediate-mass, chemically peculiar stars with strong magnetic fields give us an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in…

We have obtained a UVES spectrum of a slowly rotating strongly magnetic Ap star, HD 144897, that exhibits very large overabundances of rare-earth elements. Here we present a detailed spectral analysis of this object, also taking into…

Aims. We aim to provide observational constraints on diffusion models that predict peculiar chemical abundances in the atmospheres of Am stars. We also intend to check if chemical peculiarities and slow rotation can be explained by the…

Chemically peculiar (CP) stars are unique natural laboratories for investigation of the microscopic diffusion processes of chemical elements. The element segregation under the influence of gravity and radiation pressure leads to the…

Direct imaging suggests that there is a Jovian exoplanet around the primary A-star in the triple-star system HD131399. We investigate a high-quality spectrum of the primary component HD131399A obtained with FEROS on the ESO/MPG 2.2m…

A portion of the upper main-sequence stars, called chemically peculiar (CP) stars, show significant abundance anomalies mainly due to atomic diffusion of chemical elements within the stellar atmospheres of these stars. Slowly rotating CP…

Evolutionary trends in the surface abundances of heavier elements have recently been identified in the globular cluster NGC 6397 ([Fe/H]=-2), indicating the operation of atomic diffusion in these stars. Such trends constitute important…

We present the results of a study of the photospheric abundances of the HgMn star HD 175640, conducted using archival ESO-UVES spectra. A large number of unblended (titanium, chromium, manganese and iron) lines were studied to search for…

HD~63401 is known magnetic chemically peculiar (mCP) star that shows a slow rotation and probably possesses a hydrodynamically stable stellar atmosphere. In the latter case the atomic diffusion mechanism enforced by the magnetic field can…

In this paper we present a detailed spectroscopic analysis of the suspected marginal Am star HD\,71297. Our goal is to test the accuracy of two different approaches to determine the atmospheric parameters effective temperature, gravity,…

We present the results of a self-consistent spectroscopic analysis of the atmosphere of Ap-star HD 108662 based on high resolution spectrum and low resolution spectrophotometric observations. Magnetic field effects, such as Zeeman…