Related papers: Polar Fields for AB Dor
The magnetic cycle on the Sun consists of two consecutive 11-yr sunspot cycles and exhibits a polarity reversal around sunspot maximum. Although solar dynamo theories have progressively become more sophisticated, the details as to how the…
We present a spectropolarimetric snapshot survey of solar-type planet hosting stars. In addition to 14 planet-hosting stars observed as part of the BCool magnetic snapshot survey, we obtained magnetic observations of a further 19…
The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind. However, because our view of the Sun is limited in the ecliptic plane, the polar regions remain largely uncharted. Using…
We aim at a highly sensitive search for weak magnetic fields in main sequence stars of intermediate mass, by scanning classes of stars with no previously reported magnetic members. After detecting a weak magnetic field on the normal,…
An extremely weak circularly-polarized signature was recently discovered in spectral lines of the chemically peculiar Am star Sirius A (Petit et al. 2011). This signal was interpreted as a Zeeman signature related to a sub-gauss…
Using spectropolarimetry, we investigate the large-scale magnetic topologies of stars hosting close-in exoplanets. A small survey of ten stars has been done with the twin instruments TBL/NARVAL and CFHT/ESPaDOnS between 2006 and 2011. Each…
North-south asymmetry of sunspot activity resulted in an asynchronous reversal of the Sun's polar fields in the current cycle. The asymmetry is also observed in the formation of polar coronal holes. A stable coronal hole was first formed at…
Weak magnetic fields have recently been detected in a number of A-type stars, including Vega and Sirius. At the same time, space photometry observations of A- and late B-type stars from Kepler and TESS have highlighted the existence of…
Recent observations suggest that stellar magnetic activity may be influenced by the presence of a close-by giant planet. Specifically, chromospheric hot spots rotating in phase with the planet orbital motion have been observed during some…
The magnetic field in the Sun's corona stores energy that can be released to heat the coronal plasma and drive solar eruptions. Measurements of the global coronal magnetic field have been limited to a few snapshots. We present observations…
We study the magnetic flux carried by pores located outside active regions with sunspots and investigate their possible contribution to the reversal of the global magnetic field of the Sun. We find that they contain a total flux of…
Polaris is a highly unusual Cepheid with observed properties that are difficult to reconcile with stellar evolutionary models. Since the initial detection of Polaris' magnetic field in 2020, we have conducted a magnetic monitoring campaign…
We perform a numerical simulation of the corona of the young, rapidly rotating K0 dwarf AB Doradus using a global MHD model. The model is driven by a surface map of the radial magnetic field constructed using Zeeman-Doppler Imaging. We find…
Context. The solar corona maintains temperatures of a million Kelvin or more. The plasma heating mechanisms responsible for these extreme temperatures are still unclear. Large regions of magnetic activity in the photosphere cause extreme…
Kepler-78 is host to a transiting 8.5-hour orbit super-Earth. In this paper, the rotation and magnetic properties of the planet host star are studied. We first revisit the Kepler photometric data for a detailed description of the rotation…
The understanding of the solar magnetic coronal structure is tightly linked to the shape of open field regions, specifically coronal holes. A dynamically evolving coronal hole coincides with the local restructuring of open to closed…
Magnetic fields in cool stars can be investigated by measuring Zeeman line broadening and polarization in atomic and molecular lines. Similar to the Sun, these fields are complex and height-dependent. Many molecular lines dominating M-dwarf…
The variation of the vector magnetic field along structures in the solar corona remains unmeasured. Using a unique combination of spectropolarimetry and stereoscopy, we infer and compare the vector magnetic field structure and…
Classical Cepheids are essential objects in the study of stellar evolution and cosmology; however, we know little about their magnetic properties. We report the detection of Stokes $V$ features interpreted as Zeeman signatures in four…
The Sun's surface field, especially the polar field, sets the boundary condition for the coronal and heliospheric magnetic fields, but also provides us insight into the dynamo process. The evolution of the polar fields results from the…