Related papers: Complexity of magnetic fields on red dwarfs
Context: About 10% of white dwarfs have magnetic fields with strength in the range between about 10^5 and 3x10^8 G. It is not known whether the remaining white dwarfs are not magnetic, or if they have a magnetic field too weak to be…
Approximately 7% of massive stars host stable surface magnetic fields that are strong enough to alter stellar evolution through their effect on the stellar wind. It is therefore crucial to characterize the strength and structure of these…
The Zeeman effect and dust grain alignment are two major methods for probing magnetic fields (B-fields) in molecular clouds, largely motivated by the study of star formation, as the B-field may regulate gravitational contraction and channel…
Stellar magnetic fields have a major impact on space weather around exoplanets orbiting low-mass stars. From an analysis of Zeeman-broadened Fe I lines measured in near-infrared SDSS/APOGEE spectra, mean magnetic fields are determined for a…
New magnetic Ap stars with split Zeeman components are presented. These stars were discovered from observations with the FEROS spectrograph at the ESO 2.2-m telescope. Fifteen new magnetic stars are analysed here. Several stars with very…
Recent observations show that chromospheric activity in late-M and L dwarfs is much lower than in the earlier M types, in spite of comparatively rapid rotation. We investigate the possibility that this drop-off in activity results from the…
We investigate the luminosity and cooling of highly magnetized white dwarfs with electron-degenerate cores and non-degenerate surface layers where cooling occurs by diffusion of photons. We find the temperature and density profiles in the…
Circular polarisation measurements of white dwarfs of various ages and spectral types are useful to understand the origin and evolution of the magnetic field in degenerate stars. In the latest stages of white dwarf evolution, when stars are…
The influence of strong, large-scale magnetic fields on the structure and temperature distribution in white dwarf atmospheres is investigated. Magnetic fields may provide an additional component of pressure support, thus possibly inflating…
Magnetic fields are essential ingredients of many physical processes in the interiors and envelopes of cool stars. Yet their direct detection and characterisation is notoriously difficult, requiring high-quality observations and advanced…
The magnetic fields of the accreting white dwarfs (WDs) in magnetic cataclysmic variables (mCVs) determine the accretion geometries, the emission properties, and the secular evolution of these objects. We determine the structure of the…
Accurate tracers of the stellar magnetic field and rotation are cornerstones for the study of M dwarfs and for reliable detection and characterization of their exoplanetary companions. Such measurements are particularly challenging for old,…
We aim to characterise the magnetic field of the eclipsing binary CU Cnc. The determination of magnetic field parameters of this target enables comparisons with both observations of similar stars and theoretical predictions of the magnetic…
The convective envelopes of cool main-sequence stars harbour magnetic fields with a complex global and local structure. These fields affect the near-surface convection and the outer stellar atmospheres in many ways and are responsible for…
We have identified a new, cool magnetic white dwarf in the New Luyten Two-Tenths (NLTT) catalogue. The high proper-motion star NLTT 10480 (mu=0.5"/year) shows weak Zeeman-split lines of calcium, as well as characteristic Halpha and beta…
A significant fraction of white dwarfs harbour a magnetic field with strengths ranging from a few kG up to about 1000 MG. The fraction appears to depend on the specific class of white dwarfs being investigated and may hold some clues to the…
Context. The interplay between surface magnetic topology and chromospheric heating in active M dwarfs remains poorly constrained, limiting our understanding of their magnetic cycles and high-energy environments. Aims. We aim to test whether…
The magnetic white dwarfs (MWDs) are found either isolated or in interacting binaries. They divide into two groups: a high field group (0.1-1,000MegaGauss) comprising some 13% of all white dwarfs (WDs), and a low field group (B<0.1MG) whose…
We present an analysis of all single white dwarf stars known to exhibit spectroscopic signatures of neutral helium line splitting due to the presence of a strong magnetic field. Using state-of-the-art models taking into account the effects…
We investigate the detectability of Zeeman broadening in optical Stokes I spectra of slowly rotating sun-like stars. To this end, we apply the LTE spectral line inversion package SPINOR to very-high quality CES data and explore how fit…