Related papers: Spectroscopic variability and magnetic fields of H…
Observations at various wavelengths of late B-type stars exhibiting strong overabundances of the chemical elements Hg and Mn in their atmospheres indicate that these stars are frequently found in binary and multiple systems. We intend to…
We performed a highly sensitive search for magnetic fields on a large set of HgMn stars. With the aid of a new polarimeter attached to the HARPS spectrometer at the ESO 3.6m-telescope, we obtained high-quality circular polarization spectra…
The upper main sequence magnetic chemically peculiar (Ap) stars exhibit a non-uniform distribution of chemical elements across their surfaces and with height in their atmospheres. These inhomogeneities, responsible for the conspicuous…
The important result achieved in our recent study of a large sample of HgMn stars using UVES at the VLT and FEROS at the ESO 2.2m telescope is the finding that most HgMn stars exhibit spectral variability of various chemical elements,…
AR Aur is the only eclipsing binary known to contain a HgMn star, making it an ideal case for a detailed study of the HgMn phenomenon. HgMn stars are a poorly understood class of chemically peculiar stars, which have traditionally been…
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…
Chemically peculiar stars of the mercury-manganese (HgMn) type represent a new class of spotted late-B stars, in which evolving surface chemical inhomogeneities are apparently unrelated to the presence of strong magnetic fields but are…
Recent results obtained by various authors on the properties of HgMn stars are reviewed. Substantial progress has been achieved in the study of abundances and isotopic anomalies. The results about the magnetic fields and membership in…
The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. We re-analyse available spectropolarimetric material by…
The main-sequence mercury-manganese (HgMn) stars are known to exhibit large overabundances of exotic elements and, similar to magnetic Ap/Bp stars, are spectrum variables, implying the presence of an inhomogeneous element distribution over…
Major improvements in models of chemically peculiar stars have been achieved in the past few years. With these new models it has been possible to test quantitatively some of the processes involved in the formation of abundance anomalies and…
A fraction of late B-type stars, the so-called HgMn stars, exhibit enhanced absorption lines of certain chemical elements, notably Hg and Mn, combined with an underabundance of He. For about a decade now the elements with anomalously high…
Mercury-manganese (HgMn) stars have been considered as non-magnetic and non-variable chemically peculiar (CP) stars for a long time. However, recent discoveries of the variability in spectral line profiles have suggested an inhomogeneous…
The stars of the middle main sequence have relatively quiescent outer layers, and unusual chemical abundance patterns may develop in their atmospheres. The presence of chemical peculiarities reveal the action of such subsurface phenomena as…
Recently, with the goal to study multiplicity of chemically peculiar stars, we carried out a survey of 40 stars using diffraction limited near infrared (IR) imaging with NAOS-CONICA (NACO) at the VLT. Here, we announce the detection of 27…
It is essential for the understanding of stellar structure models of high mass stars to explain why constant stars, non-pulsating chemically peculiar hot Bp stars and pulsating stars co-exist in the slowly pulsating B stars and beta Cephei…
We present the results of a high spectral resolution study of the eclipsing binary AR Aur. AR Aur is the only known eclipsing binary with a HgMn primary star exactly on the ZAMS and a secondary star still contracting towards the ZAMS. We…
The photospheres of about 10-20% of main sequence A- and B-type stars exhibit a wide range of chemical peculiarities, often associated with the presence of a magnetic field. It is not exactly known at which stage of stellar evolution these…
The inhomogeneous surface distribution of heavy elements is known to cause periodic light variability of magnetic chemically peculiar stars. It is unclear to what extent the same paradigm applies to mercury-manganese (HgMn) stars. We aim to…
The origin of the strong magnetic fields observed in chemically peculiar Ap and Bp stars stars has long been debated. The recent discovery of magnetic fields in the intermediate mass pre-main sequence Herbig Ae and Be stars links them to Ap…