Related papers: Dark structures in sunspot light bridges
The Interface Region Imaging Spectrograph (IRIS) mission provides high-resolution observations of the chromosphere and transition region. We try to determine whether the light walls exist somewhere else in active regions besides light…
We present the first results of sunspot oscillations from observations by the Interface Region Imaging Spectrograph. The strongly nonlinear oscillation is identified in both the slit-jaw images and the spectra of several emission lines…
Discrete far-infrared (FIR) sources of M31 are identified in the ISO 175um map and characterized via their FIR colours, luminosities and masses. With a mean size of 800pc, they probably represent several clouds in chance projection or giant…
The physics of Sunspots is a fascinating and demanding field of research in solar astronomy. Interaction of magnetic fields and plasma flows takes place in a tangled magnetic geometry and occurs on spatial scales that pose a continuous…
We report the bi-directional moving structures in a coronal bright point (CBP) on 2015 July 14. It is observed by the Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). This CBP has a lifetime of about 10 minutes,…
Context. It is unclear why there is a rather sharp boundary in sunspots between the umbra and the penumbra. Both regions exhibit magnetoconvection, manifesting in penumbral filaments in the penumbra and in umbral dots in the umbra. Aims.…
Sunspots harboring umbrae of both magnetic polarities within a common penumbra (delta-spots) are often but not always related to flares. We present first near-infrared (NIR) observations (Fe I 1078.3 nm and Si I 1078.6 nm spectra) obtained…
We study the formation of a sunspot penumbra in the active region NOAA11024. We simultaneously observed the Stokes parameters of the photospheric iron lines at 1089.6 nm with the TIP and 617.3 nm with the GFPI spectropolarimeters along with…
Results from a realistic simulation of 3D radiative magneto-convection in a strong background magnetic field corresponding to the conditions in sunspot umbrae are shown. The convective energy transport is dominated by narrow upflow plumes…
Comparison of photographic observations and vector-magnetograph measurements demonstrate, that the outer boundary of the sunspot penumbra --even in complex sunspot groups-- closely follows the 0.075T isogauss line of the total value of the…
We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3…
We present optical imaging and long slit spectroscopic observations of 9 luminous type 2 AGNs within the redshift range 0.3<z<0.6 based on VLT-FORS2 data. Most objects (6/9) are high luminosity Seyfert 2, and three are type 2 quasars…
We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO) heterostructures. In spite of 2D growth observed in reflection high energy electron diffraction, Transmission Electron Microscopy images revealed that the samples tend to…
We present the results of high resolution co-temporal and co-spatial photospheric and chromospheric observations of sunspot penumbral intrusions. The data was taken with the Swedish Solar Telescope (SST) on the Canary Islands. Time series…
The dynamics of active region (AR) 12673 is qualitatively studied using observational data obtained with the Helioseismic and Magnetic Imager of the Solar Dynamics Observatory on August 31--September 8, 2017. This AR was remarkable for its…
We present the first direct ejecta velocity measurements of Tycho's supernova remnant (SNR). Chandra's high angular resolution images reveal a patchy structure of radial velocities in the ejecta that can be separated into distinct…
We present spectropolarimetric observations of an active region recorded simultaneously in the H$\alpha$ Ca II 8662 {\AA} lines. The sunspot exhibits multiple structures, including a lightbridge and a region where Ca II 8662 {\AA} line core…
Recent numerical simulations and observations of sunspots show a significant amount of opposite polarity magnetic field within the sunspot penumbra. Most of the opposite polarity field is associated with convective downflows. We present an…
High spatial resolution spectro-polarimetric observation of a decaying spot was observed with the Diffraction Limited Spectro-Polarimeter. The spatial resolution achieved was close to the diffraction limit (0."18) of the Dunn Solar…
Aims. We aim to determine the redshift (or stringent lower limits) of a number of bright BL Lacs objects. Methods. We secured medium resolution optical and near-infrared spectra of 4 bright BL Lac objects of unknown redshift using the…