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Category/Subcategory: Natural Sciences/Astronomy

Stellar magnetic activity and variability of oscillation parameters - An investigation of 24 solar-like stars observed by Kepler

Author: René Kiefer
Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with its activity cycle and these changes provide diagnostics ... more

Views: 468

Measurement of the VLT pupil motions using a 2 × 2 lenslet evaluated aberrations

Author: Narsireddy Anugu
We present the telescope pupil tracking strategy for the GRAVITY interferometer.

Views: 396

The GREGOR Fabry‐Pérot Interferometer (GFPI) ‐ Technical Innovations and Results achieved in 2013

Author: Klaus Gerhard Puschmann
This paper shall provide a summary of not yet published technical innovations to the GREGOR Fabry-Pérot Interferometer (GFPI) at the 1.5m GREGOR Solar Telescope (Europe's largest solar telescope) that I implemented in 2013 as the ... more

Views: 1072

Observational evidence for variations of the acoustic cutoff frequency with height in the solar atmosphere

Author: Aneta Wisniewska
Direct evidence for the existence of an acoustic cuto frequency in the solar atmosphere is given by observations performed by using the HELioseismological Large Regions Interferometric DEvice operating on the Vacuum Tower Teles ... more

Views: 361

The Importance of Long-term Synoptic Observations and Data Sets for Solar Physics and Helioseismology

Author: Markus Roth
A casual single glance at the Sun would not lead an observer to conclude that it varies. The discovery of the 11-year sunspot cycle was only made possible through systematic daily observations of the Sun over 150 years and even to ... more

Views: 437

Experimental results for infrared aberration tracking using a correlation algorithm on two star extended field

Author: Narsireddy Anugu
We report an experimental results of different correlation algorithms for an extended source wavefront sensor.

Views: 438

VARIATION OF ACOUSTIC CUTOFF PERIOD WITH HEIGHT IN THE SOLAR ATMOSPHERE: THEORY VERSUS OBSRVETIONS

Author: Aneta Wisniewska
Recently Wiśniewska et al. demonstrated observationally how the acoustic cutoff frequency varies with height in the solar atmosphere including the upper photosphere and the lower and middle chromosphere, and showed that the obser ... more

Views: 407

Global helioseismic evidence for a deeply penetrating Solar meridional flow consisting of multiple flow cells

Author: Markus Roth
We use a novel global helioseismic analysis method to infer the meridional flow in the deep Solar interior. The method is based on the perturbation of eigenfunctions of Solar p modes due to meridional flow. We apply this method ... more

Views: 688

Design, development and calibration of the GRAVITY acquisition camera software to monitor four telescope beams

Author: Narsireddy Anugu
We report the development of the GRAVITY acquisition camera software to monitor and analyse the four very large telescopes interferometer beams.

Views: 355