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The so-called „Denkschriften“ (in content and scope comparable to the decadal report in the US) by the astronomical and astrophysical community have become a kind of tradition in Germany – the previous ones appeared in 1962, 1987, and 2003, and have had considerable science-political influence. “The many breakthroughs of the past decades have only been possible owing to the access to exquisite research infrastructures on the ground and in space,” says Prof. Dr. Matthias Steinmetz, Scientific Director of the Leibniz Institute for Astrophysics Potsdam (AIP), president of the German Astronomical Society (in German: Astronomische Gesellschaft) and coordinator of the Denkschrift 2017.

The quintessence of the Denkschrift are the recommendations regarding the participation of Germany in the most important international telescope projects and observatories. In the first place, this involves observatories such as the ESO’s Extremely Large Telescope, which with a mirror diameter of 39 meters will be the “biggest eye on the sky”, as well as the planned facilities on the European Infrastructure Roadmap, such as the radio telescope project Square Kilometre Array (SKA) and the European Solar Telescope (EST). In space science, missions of ESA’s Cosmic Vision program are especially important. Astronomers in Germany actively participate in many of these projects, often in leading positions. In addition to the European ground-based and space-based observatories, individual and bilateral projects should be pursued – especially considering the long-term nature of these projects and in order to keep the specialists of the different disciplines in Germany.

The Denkschrift 2017 is also available online at:
www.denkschrift2017.de
As to primarily address the science-political landscape and decision makers in Germany, the document is written in German. At the beginning, however, there is an Executive Summary in English. The Denkschrift 2017 is based on 20 strategy papers in English that are also published on the website.

Original press release by the German Astronomical Society (in German): www.astronomische-gesellschaft.de/de/aktivitaeten/pressemitteilungen/pmdenk

Science contact: Prof. Dr. Matthias Steinmetz, +49 331-7499 801, msteinmetz@aip.de

Media contact: Dr. Janine Fohlmeister, +49 331-7499 803, jfohlmeister@aip.de

Image: From the left to the right: Prof. Dr. Sami K. Solanki (Director of the Max Planck Institute for Solar System Research), Prof. Dr. Matthias Steinmetz (President of the German Astronomical Society), Prof. Dr. Eva Grebel (Director of Astronomisches Recheninstitut at the Centre for Astronomy of Heidelberg University), Prof. Dr. Joachim Wambsganß (Vice President of the German Astronomical Society) und Prof. Dr. Jörn Wilms (University Erlangen-Nürnberg) presenting the Denkschrift 2017. (Photograph by: Thomas Klawunn)

The key areas of research at the Leibniz Institute for Astrophysics Potsdam (AIP) are cosmic magnetic fields and extragalactic astrophysics. A considerable part of the institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world's first observatory to emphasize explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.

“The spectra that we obtained are highly dynamic,” explains AIP researcher Dr. Ilya Ilyin. “The origin of the light we measured lies in different areas of the Sun, for that reason their shape is slightly alternating.” The solar eclipse made the chromosphere better visible – the layer of the Sun’s atmosphere that is above the photosphere but below the corona, its outermost layer. Usually, the chromosphere is very difficult to see against the brightness of the inner photosphere. Only if the moon obscures the photosphere during an eclipse, chromospheric lines from the solar limb contribute to the spectrum.

In Arizona, there was a partial eclipse visible on 21 August 2017, which means that the moon was partially obscuring the innermost layer of the Sun’s atmosphere. “The chromospheric lines got increasingly stronger because the photosphere was more and more obscured,” says Ilyin. The researchers were performing analysis of the so-called Sodium D1 line that is formed in the solar chromosphere. They obtained around one hundred spectra during the course of the eclipse between 9:16 MST and 12:03 MST in the two wavelength regions 422 to 477 and 536 to 628 nanometers.

The spectrograph PEPSI, built by the AIP in Potsdam, has been installed on the LBT in 2015. The LBT uses two 8.4 meters large mirrors, which make it effectively an 11.8 meter telescope. The objective for the solar telescope SDI is to take high signal-to-noise solar spectra continuously on every day over the whole solar magnetic cycle to study the pressure modes of solar pulsations in high resolution. “Our main goal is to compare the solar surface with the surfaces of other stars and thereby better learn about its surface magnetism”, says the PEPSI Principal Investigator Prof. Dr. Klaus Strassmeier. The reseachers also want to determine if the line profiles vary along the course of a solar cycle.

Changes of the line asymmetry of all Na D1 spectra, which were taken during the solar eclipse. Image by: AIP/Ilya Ilyin

The Sodium D2 and D1 lines, formed in the solar chromospere. All spectra recorded during the observation with SDI in two wavelength regions. This high quality spectrum exemplifies the abilities of PEPSI. Image by: AIP/Ilya Ilyin

The partial sun eclipse observed with SDI. Video: AIP/Carsten Denker, Ekaterina Dineva, Ilya Ilyin

Scientific contacts:
Dr. Ilya Ilyin, ilyin@aip.de, +49 331 7499-269
Prof. Dr. Klaus G. Strassmeier, kstrassmeier@aip.de, +49-331-7499-223

Media contact: Katrin Albaum, 0331 7499-803, presse@aip.de


The key areas of research at the Leibniz Institute for Astrophysics Potsdam (AIP) are cosmic magnetic fields and extragalactic  astrophysics. A considerable part of the institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world's first observatory to emphasize explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.

Around 7,500 historic buildings, parks, or archaeological sites in Germany open their doors on the Day of the Open Heritage Site. The AIP offers visitors two lectures and tours. Furthermore, he outdoor grounds of the AIP campus Babelsberg will be open for visitors.

The program at AIP:
10 am to 6 pm
The outdoor grounds of the AIP campus in Babelsberg will be open and can be visited

11.30 am and 3 pm
Talk by Jörn Limberg, Untere Denkmalschutzbehörde Stadt Potsdam, about the „Villenkolonie Neubabelsberg“
Location: Lecture hall Schwarzschildhaus

1 pm and 2 pm
Tour over the campus Babelsberg including the inside of historical buildings
Meeting point: In front of Schwarzschildhaus

6 pm
Concert of „Duck Tape Ticket“ (Potsdamer Jazztage)

More information (in German):
tag-des-offenen-denkmals.de
www.potsdamer-dreiklang.de

The novel adaptive optics facility (AOF) developed by ESO has been tested for the first time with the MUSE instrument. The Multi Unit Spectroscopic Explorer (MUSE) itself is a complex 3D spectrograph that can simultaneously record thousands of spectra of entire regions on the sky and reconstruct images from this data. Scientists from the Leibniz-Institute for Astrophysics Potsdam (AIP) took part in the development of MUSE and the commissioning of the adaptive optics mode. The overall lead of the project is at the Observatoire de Lyon (CRAL) and at ESO.

Andreas Kelz, the local project manager at the AIP, explains: "Astronomical images, taken with ground-based telescopes are always slightly blurred because turbulence in the air distorts the light and thus the resulting image. With the adaptive optics enabled, most of the atmospheric turbulence can be compensated. This stabilizes and sharpens the image and more details become visible." Peter Weilbacher, a scientist at AIP who was involved in the first observations with MUSE and its adaptive optics, is impressed with the results he obtained: "We have observed different objects in the southern sky and the improvement of the image quality is spectacular. Around the Planetary Nebula IC 4406 in the constellation of Lupus, shell structures could be observed which were not visible before."

What sounds so simple is based on one of the most advanced technology that has been put into practice for the first time on the Very Large Telescope. The adaptive optics facility (AOF) of ESO consists of three systems: Four high-power lasers illuminate layers of the Earth's atmosphere at an altitude of 80 km, stimulating sodium atoms to glow, thus projecting "artificial stars" into the night sky. Sensors in the GALACSI (Ground Atmospheric Layer Adaptive Corrector for Spectroscopic Imaging) module use these artificial laser stars to measure the atmospheric turbulence. Finally, the calculated corrections are sent to a one meter large deformable mirror at the telescope. Its curvature is slightly adjusted several hundred times per second which compensates the blurring effect.

These corrections provide two essential advantages for astronomical observations: with the increased image sharpness, extended structures are depicted in much more detail. Moreover, cosmic objects that are very faint become detectable at all. "One of our key scientific projects is the observation of distant galaxies that have emitted their light over 10 billion years ago. These objects appear so small and faint that long exposure times with stable conditions are required. With the support of the adaptive optics, this can be achieved much better now." says Lutz Wisotzki, program scientist of MUSE at the AIP. "The first results with the adaptive optics for MUSE fulfil the high expectations." Kelz is delighted. The scientists at the AIP are now looking forward to further astronomical discoveries in the coming years.

The German MUSE partners from the astrophysical institutes in Potsdam (AIP) and Göttingen (IAG) are supported by the Federal Ministry of Education and Research (BMBF).

NGC 6563 is a planetary nebula in the constellation Sagittarius. The impressive image was reconstructed from the MUSE data cubes using the data reduction software developed by AIP. Through the support of the adaptive optics, weak structures in the nebula are being recognized, which were not visible before. The image on the left was taken without using adaptive optics and the one on the right was made using adaptive optics.
Credit: ESO / P. Weilbacher (AIP)

ESO 338-IG04 is a starburst galaxy in the constellation Sagittarius, which is likely triggered by merging events. The new data from MUSE with the adaptive optics clearly reveal different bright knots, which mark the places of intense star formation. Luminous, hot hydrogen gas forms the filamentary structures in the outer areas.
Quelle: ESO / P. Weilbacher (AIP)

The laser system in operation at the European Southern Observatory during the first observations with the AOF-assisted MUSE instrument. The adaptive optics partly compensates for the turbulence of the air and enables sharper images of astronomical targets. The stars of the Milky Way stretch over the observatory in the Chilean Atacama desert.
Quelle: P. Weilbacher (AIP)

Further information:

• ESO press release including pictures: https://www.eso.org/public/news/eso1724/
• MUSE website at AIP:
  http://www.aip.de/de/forschung/research-area-drt/development-of-research-technology-and-infrastructure-1/3d-spectroscopy/muse/development-of-the-muse-integral-field-spectrograph
• Virtual Reality Tour of the VLT Observatorium: https://vr.aip.de/aipvr.html?s=pano1870
• MUSE Homepage: http://muse-vlt.eu/science/

MUSE is a joint project of seven European Research Institutes,

• led by the Centre de Recherche Astrophysique de Lyon (CRAL, France),
• the Leibniz-Institut für Astrophysik Potsdam (AIP, Germany),
• the Institut für Astrophysik der Universität Göttingen (IAG, Germany),
• the Institut de Recherche en Astrophysique et Planétologie (IRAP, France),
• the Sternwarte Leiden and the Niederländischen Forschungsakademie für Astronomie (NOVA, Netherlands),
• the Institut für Astronomie der Eidgenössischen Technischen Hochschule Zürich (ETH, Switzerland) and
• the European Southern Observatory (ESO).

Scientific contacts:

Dr. Andreas Kelz, 0331 7499-640, akelz@aip.de
Dr. Peter Weilbacher, 0331 7499-667, pweilbacher@aip.de
Prof. Dr. Lutz Wisotzki, 0331 7499-532, lwisotzki@aip.de

Media contact:

Janine Fohlmeister, 0331 7499-802, presse@aip.de

The key areas of research at the Leibniz Institute for Astrophysics Potsdam (AIP) are cosmic magnetic fields and extragalactic  astrophysics. A considerable part of the institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world's first observatory to emphasize explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.

The Great Refractor of the AIP is a monument of astrophysical research and a landmark of Potsdam. The huge lens telescope was inaugurated for the first time on 26 August 1899, in the presence of Emperor Wilhelm II as the main telescope of the Astrophysical Observatory Potsdam. Today, it is still the fourth largest lens telescope in the world.

Science minister Martina Münch honored the restored Great Refractor as an important scientific landmark in Potsdam. "The Great Refractor and Telegrafenberg campus were important science centers not only more than 100 years ago - they are still today. The Leibniz Institute for Astrophysics Potsdam is an outstanding non-university research institution in the state of Brandenburg and has been one of the most renowned and research-oriented scientific institutions in Germany for years", says Münch. Matthias Winker, administrative head of the AIP, gave the welcome adress. In addition to the minister, Prof. Dr. Matthias Steinmetz, chairman of the board and scientific director of the AIP, greeted the guests. Monument protection expert Jörg Limberg gave a lecture on the structural aspects and the renovation of the dome building. Between May 2016 and May 2017, numerous specialist companies and skilled workers carried out the repair work.

The telescope is a double refractor with two fixed telescopes on an equatorial mount. The larger tube has an 80 cm lens and a focal length of 12.2 meters. The smaller lens, designed for visual observation, has a diameter of 50 centimeters and a focal length of 12.5 meters. The diameter of the rotating 200-tonne dome is 21 meters. In 1904, diffuse interstellar matter was discovered by Johannes Hartmann, using the Great Refractor.

Science contact: Prof. Dr. Matthias Steinmetz, +49 331 7499-801, sek-vorstand@aip.de

Media contact: Kristin Riebe, Janine Fohlmeister, +49 331 7499-803, presse@aip.de

The key areas of research at the Leibniz Institute for Astrophysics Potsdam (AIP) are cosmic magnetic fields and extragalactic  astrophysics. A considerable part of the institute's efforts aim at the development of research technology in the fields of spectroscopy, robotic telescopes, and e-science. The AIP is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory of Potsdam founded in 1874. The latter was the world's first observatory to emphasize explicitly the research area of astrophysics. The AIP has been a member of the Leibniz Association since 1992.