Aims: We analyze a set of full Stokes profile observations of the flaring active region NOAA 10808. The region was recorded with the Vector-Spectromagnetograph of the Synoptic Optical Long-term Investigations of the Sun facility. The active region …
Numerical simulations of solar surface convection have predicted the existence of supersonic horizontal flows in the photospheric granulation. Recently, the detection of such flows in data from the Hinode satellite was reported. We study supersonic …
Convective collapse, a theoretically predicted process that intensifies existing weak magnetic fields in the solar atmosphere, was first directly observed in a single event by Nagata et al. (2008, ApJ, 677, L145) using the high resolution Solar …
The photospheric magnetic field outside of active regions and the network has a ubiquitous and dynamic line-of-sight component that strengthens from disk center to limb as expected for a nearly horizontal orientation. This component shows a striking …
A solar photospheric ``thermal profiling`` analysis is presented, exploiting the infrared (2.3-4.6 ensuremathμm) rovibrational bands of carbon monoxide (CO) as observed with the McMath-Pierce Fourier transform spectrometer (FTS) at Kitt Peak, and …
Solar faculae appear as bright small features close to the solar limb. Recent high-resolution images show these brightenings in unprecedented detail. Our analysis of numerical MHD simulations reproduces the observed small-scale features. The …
Observations of Ti I lines at 2.2 micrometer show that the Evershed flow takes place in cool, almost horizontal channels with a low magnetic field strength (~500-900 G) that does not appear to change significantly across the penumbra. This property …
The first systematic observations of sunspot umbrae using the lines of the Ti Ii multiplet at 2.2 mu m are presented. Their diagnostic capabilities are investigated, developed and used to investigate the magnetic and velocity structure of a sunspot. …
The combination of the German Vacuum Tower Telescope and the prototype of ZIMPOL I (Zuerich Imaging Stokes Polarimeter I), a novel, very sensitive imaging polarimeter, has resulted in the first spectra of solar intra-network (IN) fields in circular …