Picture of the Month

The ESA satellite Solar Orbiter will approach the Sun as close as 0.28 astronomical units, closer than any other satellite before. Start of the mission is planned for 2017.

KIS participates in the Solar Orbiter project by building the Image Stabilization System (ISS) for the Polarimetric and Helioseismic Imager (PHI).

During closest approach PHI will measure the magnetic field in the polar regions of the Sun with high accuracy. The ISS will provide the required pointing stability to obtain such accurate measurements.

The ISS consists of a fast tip-tilt mirror in the optical path of the telescope and a high-speed camera. The measured image motion is used to control the tipp-tilt mirror to compensate for that motion in real time.

Recently lab tests have shown that the prototype ISS system performance clearly exceeds the specifications.

Image 1 shows the required (thin curve) and actually measured (thick black and red curves) motion damping of the system.  The actual damping is...

Read more

Three-dimensional computer simulations of magneto-acoustic wave propagation in a solar model atmosphere with a complex magnetic field structure, reveal the physics of a phenomenon known as "magnetic shadow''. In these simulations, acoustic waves of 10 mHz frequency are excited at the bottom of the simulation domain. On their way through the upper convection zone and through the photosphere and the chromosphere they become perturbed, refracted, and converted into different mode types. Synthesized oscillatory power-maps of the line-of-sight velocity of the upper photosphere and the lower chromosphere then show the magnetic shadow as is observed on the Sun: a seam of suppressed power surrounding the magnetic network elements (see Fig. 1).

We demonstrate how this shadow is linked to the conversion of the excited wave into different modes (see Fig. 2) and that power maps in these height levels show the signature of three different magneto-acoustic wave modes in three different regions: the...

Read more

Das ballongetragene Sonnenobservatorium Sunrise, das am 12. Juni 2013 zu seinem mehr als fünftägigen Beobachtungsflug von Schweden nach Kanada gestartet war, ist nun – in Einzelteile zerlegt – auf dem Heimweg nach Deutschland. Obwohl bei der Landung am 18. Juni auf der kanadischen Halbinsel Boothia starke Winde in Bodennähe das Observatorium umwarfen, sind die wichtigsten Komponenten wie etwa die Datenspeicher, die Spiegel des Sonnenteleskops und die wissenschaftlichen Instrumente unversehrt. Das ergab die dreitägige Bergung vor Ort. Während der Großteil des Observatoriums nun in Containern verpackt den langen Heimweg auf dem Seeweg antritt, sind die Datenspeicher bereits am Max-Planck-Institut für Sonnensystemforschung (MPS) im niedersächsischen Katlenburg-Lindau angekommen.

Read more