Related papers: Superstrong magnetic fields in sunspot bipolar lig…
The axion is just one from a general class of new particles -- called Light Pseudoscalar Bosons (LPBs) -- predicted by many realistic extensions of the Standard Model. We offer a somewhat pedagogical review of their main properties, with…
Three-dimensional magnetic reconnection is a fundamental plasma process crucial for heating the solar corona and generating the solar wind, but resolving and characterizing it on the Sun remains challenging. Using high-quality data from the…
Fossil magnetic fields of early-type stars are typically characterised by symmetric or slightly distorted oblique dipolar surface geometries. Contrary to this trend, the late-B magnetic chemically peculiar star HD 57372 exhibits an…
Polarity imbalance of the photospheric magnetic field was studied using synoptic maps of NSO Kitt Peak (1976-2016). Imbalance of positive and negative fluxes was considered for the fields with strength B>50 G in the sunspot zone (5 deg - 40…
Recent observational studies suggest that Be stars most likely are formed through the process of mass transfer in binary systems. In view of the wide consensus that the origin of the magnetic field in stars with radiative envelopes involves…
High-resolution spectropolarimetric observations of active region NOAA 11271 were obtained with the spectro-polarimeter on board Hinode to analyze the properties of an anomalous flow in the photosphere in a sunspot penumbra. We detect a…
Recent progress in theoretical modeling of a sunspot is reviewed. The observed properties of umbral dots are well reproduced by realistic simulations of magnetoconvection in a vertical, monolithic magnetic field. To understand the penumbra,…
A precise knowledge of the surface structure of sunspots is essential to construct adequate input models for helioseismic inversion tools. We summarize our recent findings about the velocity and magnetic field in and around sunspots using…
We present polarisation measurements of sdB and sdO stars using FORS1 on the VLT. The observations were made as part of a project to determine whether magnetic fields in two super-metal-rich stars can explain their extreme abundance…
The long term study of the Sun is necessary if we are to determine the evolution of sunspot properties and thereby inform modeling of the solar dynamo, particularly on scales of a solar cycle. We aim to determine a number of sunspot…
We observed an elongated filamentary bright structure inside the umbra of the big sunspot in active region NOAA 12529, which differs from the light bridges usually observed in sunspots for its morphology, magnetic configuration, and…
We study the velocity field of umbral dots at a resolution of 0.14". Our analysis is based on full Stokes spectropolarimetric measurements of a pore taken with the CRISP instrument at the Swedish 1-m Solar Telescope. We determine the flow…
We have mapped linearly polarized dust emission from L183 with the JCMT SCUBA polarimeter and have analyzed these and our previously published data for the prestellar cores L183, L1544, and L43 in order to estimate magnetic field strengths…
Active region NOAA 11035 appeared in December 2009, early in the new solar activity cycle. This region achieved a delta sunspot ($\delta$-spot) configuration when parasitic flux emerged near the rotationally leading magnetic polarity and…
Sunspots are dark spots on the solar surface associated with strong magnetic fields. The number, area, and brightness of sunspots are supposed to reflect the intensity of the solar magnetic fields and are often used as proxies for their…
We compare the properties of kG magnetic structures in the solar network and in active region plage at high spatial resolution. Our analysis used six SP scans of the solar disc centre aboard Hinode SOT and inverted the obtained spectra of…
Context. It has been reported that the boundary between the umbra and the penumbra of sunspots occurs at a canonical value of the strength of the vertical magnetic field, independently of the size of the spot. This critical field strength…
Sunspot penumbrae show a fine structure in continuum intensity that displays considerable dynamics. The magnetic field, in contrast, although also highly structured, has appeared to be relatively static. Here we report the discovery of…
Abrupt and permanent changes of photospheric magnetic fields have been observed during solar flares. The changes seem to be linked to the reconfiguration of magnetic fields, but their origin is still unclear. We carried out a statistical…
We use high spatial and spectral resolution observations obtained with the CRisp Imaging SpectroPolarimeter at the Swedish 1-m Solar Telescope to analyze the velocity profile of granular light bridges in a sunspot. We find upflows…