Related papers: The spots on Ap stars
The positions in the H-R diagram of strongly magnetic Ap and Bp stars are compared with those of normal main sequence stars of types B7 to F2, with a view to investigating possible differences in evolutionary status between magnetic and…
Doppler imaging, a technique which inverts spectral line profile variations of an Ap star into a two-dimensional abundance maps, provides new observational constraints on diffusion mechanism in the presence of a global magnetic field. A…
High spectral resolution studies of cool Ap stars reveal conspicuous anomalies of the shape and strength of many absorption lines. This is a signature of large atmospheric chemical gradients produced by the selective radiative levitation…
Two types of stars are known to have strong, large scale magnetic fields: the main sequence Ap stars and the magnetic white dwarfs. This suggest that the former might be the progenitors of the latter. In order to test this idea, I have…
We have carried out an accurate investigation of the Ca isotopic composition and stratification in the atmospheres of 23 magnetic chemically peculiar (Ap) stars of different temperature and magnetic field strength. With the UVES…
In order to clarify the role of the magnetic field in generating abundance inhomogeneities in the atmospheres of Ap stars, we present new abundance Doppler images and an approximate magnetic field geometry for the Ap star iota Cas.
We give concisely the formulae governing diffusion of chemical elements and their isotopes in quiescent stellar atmospheres, due to electrostatic, gravitational and radiation fields and to impacts between particles. Isotope segregation of…
Strong magnetic fields are observed in a substantial fraction of upper main sequence stars and white dwarfs. Many such stars are observed to exhibit photometric modulations as the magnetic poles rotate in and out of view, which could be a…
The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit periodic light, magnetic, radio, and spectroscopic variations that can be adequately explained by a model of a rigidly rotating magnetized star with persistent…
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…
Some main-sequence stars of spectral type A are observed to have a strong (300-30000 G), static, large-scale magnetic field, of a chiefly dipolar shape -- the `Ap stars' (for example Alioth, the fifth star in the Big Dipper). Following…
The magnetic field is a key ingredient in the recipe of star formation. Over the past two decades, millimeter and submillimeter interferometers have made major strides in unveiling the role of the magnetic field in star formation at…
Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods:…
Sudden changes in the internal structure of stars, placed at the interface between convective and radiative regions, regions of partial ionisation, or between layers that have acquired different chemical composition as a result of nuclear…
Chemically peculiar stars define a class of stars that show unusual elemental abundances due to stellar photospheric effects and not due to natal variations. In this paper, we compare the elemental abundance patterns of the ultra metal-poor…
This paper presents the catalogue and the method of determination of averaged quadratic effective magnetic fields B_e for 596 main sequence and giant stars. the catalogue is based on measurements of the stellar effective (or mean…
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…
The light curves of magnetic, chemically peculiar stars typically show periodic variability due to surface spots that in most cases can be modeled by low-order harmonic expansion. However, high-precision satellite photometry reveals tiny…
Studies of stellar magnetism at the pre-main sequence phase can provide important new insights into the detailed physics of the late stages of star formation, and into the observed properties of main sequence stars. This is especially true…
The recently discovered magnetic Herbig Ae and Be stars may provide qualitatively new information about the formation and evolution of magnetic Ap and Bp stars. We have performed a detailed investigation of one particularly interesting…