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An astronomical midsummer night's dream with Moon and Mars

Total Lunar Eclipse on September 28, 2015. Credit: AIP/J. Weingrill

An astronomical midsummer night's dream with Moon and Mars

On the evening of July 27th, two special astronomical events will take place: the longest lunar eclipse of the 21st century and Mars close to the earth and at the same time inopposition to the sun....

The Leibniz Institute for Astrophysics Potsdam (AIP) and the Urania Planetarium Potsdam invite you to a theme evening with a lecture followed by a public observation. Anyone interested can take a look through our mobile telescopes. The experts from AIP and Planetarium will answer all the questions about the rare spectacle of heaven on site.

 

8.30 p.m.: Warm-up show in the URANIA Planetarium

10 p.m.: Public observation at the New Lustgarten
(location near Casino, only with a clear view!)

 

The event is free of charge, registration is not required.

We are looking forward to your visit!

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Using Very Pristine Stars to Study Dwarf Galaxies & the Galactic Halo

Simulation of Satellite Galaxies. The colours indicate gas densities. Credit: HESTIA project

Using Very Pristine Stars to Study Dwarf Galaxies & the Galactic Halo

Kris Youakim from the Leibniz Institute for Astrophysics Potsdam (AIP) is talking this week at the 232nd AAS meeting about his latest results on the analysis of the stellar debris in the galactic h...

Although many of these accreted smaller galaxies are heavily disrupted over time and blend into the background, with a careful analysis it is possible to see their remaining signatures. “The Milky Way halo may look smooth at first glance, but it’s far from it. When we study it closely, we see substructure everywhere.” says Youakim. “And it’s these substructures which hold the clues to understanding the tumultuous history of the formation of the galactic halo.”

The key to this analysis is the identification of very pristine stars, stars which lack heavy elements because they formed close in time to the big bang before their atmospheres were significantly “polluted” by material from previous generations of dying stars. The smallest dwarf galaxies have many of these stars, so by looking at these stars specifically and how they are clustered in the halo, the many accreted smaller galaxies and their remnants stand out from the background. Furthermore, by finding the most pristine stars we can begin to probe the early times of our galaxy, since some of them are thought to be the direct descendants of the very first generation of stars that ever formed.

Youakim and a team of international collaborators are working on “the Pristine survey,” using a specifically designed filter on the Canada-France-Hawaii Telescope to quickly search through large patches of sky to find these very pristine stars. Youakim has recently led a study demonstrating that this technique is exceptionally efficient. The team is now studying many of the discovered very pristine candidates in more detail as they can give us valuable clues as to what our galaxy used to be like in the past. Or as Youakim puts it, “These stars truly allow us to look back in time.”

 

Scientific contact at AIP

Kris Youakim, 0331-7499 301, kyouakim@aip.de

Media contact

Franziska Gräfe, 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.

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Journey to Infinity: Long Night of the Sciences 2018

Einstein Tower in the dusk. Credit: AIP

Journey to Infinity: Long Night of the Sciences 2018

The Leibniz Institute for Astrophysics Potsdam (AIP) is once again involved with offers on the Telegrafenberg at the Long Night of Sciences on June 9, 2018 from 5 to 11 pm. Visitors to the historic...

 

With the Einstein Tower - once the most scientifically important solar telescope in Europe - a story began that is still going on today. At the Long Night of Sciences, scientists give an insight into modern solar research from Potsdam.

The Great Refractor opens its doors again and invites you to wonder: in lectures, the guests can learn more about distant exoplanets or cool neighbor stars, make star charts and - in suitable weather - the night sky over Potsdam through the telescope.

The program in the Einstein Tower

6 p.m.: apl. Prof. Dr. Carsten Denker – Das Europäische Sonnenteleskop (EST) - Ein neues Sonnenteleskop für hochaufgelöste Sonnenbeobachtung
7 p.m.: Dr. Christoph Kuckein – Die Sonne und Europas größtes Sonnenteleskop GREGOR
8 p.m.: Dr. Meetu Verma (in English) – The Dynamic Sun
9 p.m.: Dr. Christian Vocks – Die Sonne - unser nächster Stern
10 p.m.: Dr. Horst Balthasar – Die Sonne und Europas größtes Sonnenteleskop GREGOR

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The program in the Great Refractor

6 p.m.: Dr. Ernst-August Gußmann –Der Große Refraktor: Zeitzeuge der Astronomie im 20. Jahrhundert

7 p.m.: Engin Keles – Exoplaneten: Die Suche nach der zweiten Erde

8 p.m.: Dr. Ralf-Dieter Scholz –Coole Nachbarsterne

9 p.m.: Live music– Jazz-Session with the Bigge-Meinig-Duo

from 10 p.m.: Observation at Great Refractor – after dark and only with a clear view

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Spinning rugby balls: The rotation of the most massive galaxies

Map of the measured mean stellar velocity of a galaxy: Blue colour means that stars in this part of the galaxy move towards us and red colours away from us. Credit: MUSE/D. Krajnovic

Spinning rugby balls: The rotation of the most massive galaxies

By targeting the most massive galaxies in our universe, astronomers have studied how their stars move. The results are surprising: while half of them spin around their short axis as expected, the o...

Surveying the extremes of the galaxy population

Measuring the way stars move within galaxies is a very powerful way of learning about the internal structure of galaxies, especially properties such as their three-dimensional shape and, ultimately, what their gravitational potential is like.

To study the largest and most massive galaxies, a science team led by Davor Krajnovic from the Leibniz Institute for Astrophysics Potsdam (AIP) selected a sample of some of the brightest galaxies up to a distance of 800 million light years. These live in large ensembles of galaxies, within some of the most densely populated regions of our Universe, such as the Shapley Supercluster. They are also very bright and rare. The most massive galaxies are about one hundred times more massive than our own galaxy the Milky Way, which itself already has a stellar mass of 60 billion suns. They also have almost no gas, most of their stars are very old (at least 10 billion years) and do not form stars anymore.

Unfortunately, these galaxies are too far from us to be resolved into individual stars and their motions. One can only look at the average motions of stars within certain regions. “This is what integral-field spectrographs are good at”, explains Davor Krajnović. „We observed these galaxies with MUSE, the wonderful integral-field spectrograph on the ESO's Very Large Telescope on Cerro Paranal in Chile. Massive galaxies can have all sorts of kinematics, some spin like frisbees, but most have no specific sense of rotation. We observed the most massive galaxies and found them to be different from other galaxies.”

From discs to rugby balls

The majority of intermediate-mass galaxies shows very regular stellar motions, as one would expect from discs like our Milky Way. In such galaxies, the sense of rotation is well defined around the shortaxis of the object; the angular momentum is aligned with the minor axis of an oblate spheroid.

“We knew that about only 15% of the intermediate mass galaxies have irregular kinematics or even don’t show much rotation at all”, says Krajnović.“For such galaxies, the sense of rotation is often not aligned with any of the symmetry axes of the galaxy, and these galaxies are of nearly spherical shape, or are elongated resembling rugby balls. Some of them have an interesting alignment and rotate around the long axis of the galaxy. Only a few cases of these were known.”

In the new study published in the Monthly Notices of the Royal Astronomical Society, the authors showed that these galactic “spinning rugby balls” are much more common than thought previously if one looks at the extremely massive galaxies, the high-mass end of the galaxy population.

The result is interesting as it points to a very specific formation scenario for these galactic giants. Numerical simulations indicate that rotation along the long axis is indicative for a merger of two massive galaxies with similar size (and mass) when they are on special trajectories: sort of a head-on collision in space.

Such galaxy collisions are violent events that completely reshape the internal structures of the progenitor galaxies. The remnant galaxies resemble spinning rugby balls. Stellar orbits also become much more complex, resulting in kinematics where the simple ordered motion is substituted with complex streaming around any of the three axes of a spheroid. The most massive galaxies are the end points of galaxy formation, and deservedly turn out to be the most complex stellar systems. This study helps us unveil the mystery of how the most massive galactic systems in the Universe come into existence.

 

The upper panels show maps of the measured mean stellar velocity of two example galaxies: Blue colour means that stars in this part of the galaxy move towards us and red colours away from us. The type of rotation for the galaxy on the left is typical for galaxies. The majority of galaxies rotate like this. The rotation around the long axes of the galaxy on the right is unusual, and applies only to a small fraction of galaxies. This fraction increases as galaxies become more massive. Credit: MUSE/D. Krajnovic

 

Publication

Davor Krajnović et al. Climbing to the top of the galactic mass ladder: evidence for frequent prolate-like rotation among the most massive galaxies, Monthly Notices of the Royal Astronomical Society (2018).  MNRAS Publication

arXiv: https://arxiv.org/abs/1802.02591

Scientific contact at AIP

Dr. Davor Krajnović, 0331-7499 237, dkrajnovic@aip.de

Media contact

Franziska Gräfe, 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.

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Sun in sight: Tailored solution for collaborative research

Three-dimensional flow field on the sun on September 26, 2016, reconstructed from GREGOR data. Credit: Carsten Denker/AIP

Sun in sight: Tailored solution for collaborative research

Since 2014, Europe's largest solar telescope GREGOR has been used for scientific measurements and has collected large amounts of very complex, multidimensional data during this time. To make these ...

With the GREGOR telescope astronomers of the AIP study active dynamic processes on the Sun with high spatial, temporal and spectral resolution. In terms of observations and data acquisition, they face particular challenges arising from various factors: Turbulence in the Earth's atmosphere affects the image quality, small solar structures develop on short time scales of a few seconds to minutes, and large-format detectors generate very large amounts of data.

"With the powerful instruments of the GREGOR telescope we are able to detect even the smallest structures on the sun's surface and provide time series of high-resolution images every 10 to 20 seconds," says Prof. Carsten Denker, head of the working group Optical Solar Physics at the AIP. "A reconstructed image every 20 seconds is based on a few hundred individual image frames. That's about 200,000 images or 4 terabytes per observation day."

The large number and high-resolution of images and spectra as well as the required computational effort in the post-processing require extensive and efficient structures for storage and archiving. In order to make the GREGOR data optimally usable and accessible, a dedicated CRE has now been implemented at AIP. This infrastructure served initially as a central data hub within the GREGOR consortium, but is now open to all interested scientists. It provides data space and access, computational resources and customized tools for analysis and processing. Collaborators have also the option to publish selected and curated data for the solar community via the CRE.

In order to make research data available to as many scientists as possible or even to the interested general public, the open access paradigm has gained increased importance in recent years. The newly developed CRE for GREGOR data also builds on this concept and is specifically tailored toward the requirements of the high-resolution solar physics community. In the now published article, AIP scientists around Prof. Carsten Denker give an overview of the GREGOR data –from the photons arriving at the detector to the final data products. In addition, they describe the developed approach for the systematic processing, analysis, management and archiving of these data.

The development of research technology and e-infrastructure is a strategic goal of AIP. In close collaboration between the two research areas of E-Science and Solar Physics, a tailor-made solution was developed for the data-specific challenges of high-resolution solar observations obtained with ground-based solar telescopes such as GREGOR.

 

GREGOR consortium

Kiepenheuer Institute for Solar Physics, Freiburg

Leibniz Institute for Astrophysics Potsdam (AIP)

Max Planck Institute for Solar System Research, Göttingen

Instituto de Astrofísica de Canarias, Canary Islands

 

Further information

Publication: https://doi.org/10.3847/1538-4365/aab773

Solar telescope GREGOR: GREGOR

Collaborative Research Environment (CRE): gregor.aip.de

 

Scientific contact at AIP

Apl. Prof. Dr. Carsten Denker, +49 331-7499 297, cdenker@aip.de

 

Media contact

Dr. Janine Fohlmeister, +49 331-7499 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.

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