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Matthias Steinmetz honoured with Foersterpreis 2015

Prof. Dr. Matthias Steinmetz

Matthias Steinmetz honoured with Foersterpreis 2015

29. April 2015. The "Wilhelm-Foerster-Preis 2015" is awarded to Matthias Steinmetz, scientific chairman of the Leibniz Institute for Astrophysics Potsdam (AIP) and director of the research area Ext...

Topics under investigation in his department extend from the structure, dynamics and chemical evolution of the Milky Way over the structure and evolution of galaxies and their massive black holes to the formation of galaxies, clusters of galaxies and the large scale cosmic web. Furthermore, researchers in this area are participating in the development of the next generation of instruments for 8m-class telescopes like the Large Binocular Telescope or ESO's Very Large Telescope and in the establishment of a E-science infrastructure for astronomy.


Matthias Steinmetz's personal research interests focus on the formation and evolution of galaxies, in particular the Milky Way. He has been actively engaged in performing high resolution simulation of the galaxy formation process. He is the principle investigator of the RAdial Velocity Experiment RAVE, a large international collaboration that over the past decade has amassed more than half a Million spectra for stars in the Galaxy.
Matthias Steinmetz is currently president of the German Astronomical Society.

The award ceremony will be held in the Nicolaisaal in Potsdam, at 5 pm on 3 May 2015. The public is welcome to attend. The laudations and the award recipients talk will be in German.

Announcement Urania Potsdam

The key topics of 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. Since 1992 the AIP is a member of the Leibniz Association

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Largest catalogue of X-ray detected astrophysical objects published

28 April 2015. A systematic analysis of all observations performed so far by the X-ray satellite XMM-Newton resulted in the worlds most comprehensive catalogue of X-ray detected celestial objects. ...

Sources that are bright in X-ray light are amongst the most energetic in the Universe. The European Space Agency's highly sensitive XMM-Newton X-ray observatory detects 50-100 X-ray sources in a region of the sky that is the same size as the full moon, and there are around 600 such observations per year. Many of the detections turn out to be objects that have never previously been observed.

Axel Schwope, team lead at the Leibniz Institute for Astrophysics Potsdam (AIP), which is responsible for the source detection software, says: “50 years ago just a handful of X-ray sources were known and scientist entered unchartered territory. Now, with half a million sources, one can make on the one hand a census of the more common objects and on the other hand search for very rare exotic objects.” Iris Traulsen, project scientist at AIP, adds: “Our source detection software is an important tool for those searches. It was continuously improved over the last years, an effort that led to an ever enhanced precision of the detection process.”

The X-ray sources in the XMM-Newton serendipitous source catalogue are objects such as supermassive black holes guzzling the gas and dust that surrounds them in the centres of galaxies, exploding stars and dead stars that have collapsed to tight balls of exotic material that are as dense as the atomic nucleus and rotate up to 1000 times per second. However, new and exotic objects are expected to be found, based on results from previous smaller versions of the catalogue.

Indeed, during the methodical data validation phase, two new extreme binary systems, known as polars were discovered. These systems contain a star like our Sun and the remains of a star that has collapsed into a 'white dwarf'. The two objects orbit each other (much like the Earth and the Moon) and the white dwarf is so dense (1 million times the density of water!) that it strips the outer layers from its companion star through its huge gravitational field. This gas and dust gets caught in the white dwarf's extra-strong magnetic field (ten million times stronger than the Earth's magnetic field) causing it to heat up and radiate strongly in the X-ray domain. In the extreme case, it is possible that so much matter can fall onto the white dwarf that it would no longer be able to support its own weight, therefore such kind of objects are candidates progenitors for type Ia supernova explosions. These explosions allow astronomers to measure the distance to remote objects in the Universe.

Natalie Webb from the Institut de Recherche en Astrophysique et Planétologie (IRAP, Toulouse, France), who is responsible for the XMM-Newton Survey Science Centre that produces the catalogue, enthuses: “This is just the tip of the iceberg – there are many more new and exciting objects waiting to be discovered in the catalogue!”

In order for scientists to make the most of the catalogue, a scientific paper submitted to the European Journal Astronomy and Astrophysics, written by the XMM-Newton Survey Science Centre consortium, describing the catalogue and its products accompanies the release of this prestigious catalogue, along with a new version of the XMM-Newton Survey Science Centre webpages.

Caption: On the map of the sky each dot represents one observation with XMM-Newton. Each of it corresponds to the size of the full moon. The galactic centre and the galactic plane (centre of the map) and our neighbour galaxies, the Magellanic clouds (lower right) were targeted often. Some of the ‘exotic animals in the high-energy zoo’ are also depicted (artists impression).

 

Resources:

IRAP press release

The XMM-Newton Survey Science Centre webpages and catalogue access: http://xmmssc.irap.omp.eu/

The paper describing the catalogue: 'The XMM-Newton serendipitous survey VI. The third XMM-Newton serendipitous source catalogue', S. R. Rosen, N. A. Webb, M. G. Watson et al., A&A.

 

Science contact AIP: Dr. Axel Schwope,+49 331 7499-232, aschwope@aip.de

Media contact AIP: Dr. Janine Fohlmeister, +49 331 7499-383, presse@aip.de

Media contact XMM-Newton Survey Science Centre: Dr. Natalie Webb, Natalie.Webb@irap.omp.eu

The key topics of 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. Since 1992 the AIP is a member of the Leibniz Association

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To flare or not to flare: The riddle of galactic thin–thick disk solved

24 April 2015. A long-standing puzzle regarding the nature of disk galaxies has finally been solved by a team of astronomers led by Ivan Minchev from the Leibniz Institute for Astrophysics Potsdam ...

We were able to show for the first time that galactic thick disks are not composed only of old stars but must also contain young stars at larger distances from the galactic centre”, explains Minchev. “The flaring seen in groups of stars with the same age is caused mostly by the bombardment of small satellite galaxies. These cosmological car crashes pummel the young disk and cause it to swell and flare.“

To arrive at this new result, the team ran numerical simulations on massive super computers and examined the structure of their simulated galaxies. The scientists grouped stars by common age and looked at where they were located. What they found was that stars of a given age group constituted a disk with flared edges, much like the mouth of a trumpet. This flaring is unavoidable, being caused when the main galaxy collides with smaller galaxies – a generic feature of how scientists believe galaxies form. Since the oldest stars formed in the inner region of the galaxy, for them this flaring occurs closer to the centre, while for the younger stars it occurs at the periphery of the galaxy. When put together, the combination of flaring from all the stars produces the elusive thick disk, as observed.

One of the most fascinating aspects of galaxies is that their stars can be separated into two components: a fluffy thick disk that enshrouds a thin disk. Until now the understanding has been that stars in the thick disk were the oldest. In observations of the Milky Way the oldest stars are found to be closer to the centre, while younger stars are more extended. Scientists agree that this separation is likely due to an “inside-out” formation scenario, wherein the Milky Way forms stars first in its center and later in its outer region, much like how cities grow radially from a medieval center to modern suburbs. Observing the structure of the Milky Way is tricky, since we are located within its disk, roughly half way from the centre. Instead, astronomers have to rely on the stars that surround us and build a model from this limited perspective. Nevertheless, if the Milky Way were similar to other galaxies and its thick disk were composed only of old, centrally concentrated stars, then one would naively expect its thick disk to be short. But in other galaxies the thick disks are observed to be as extended as the galaxies themselves. Minchev’s results resolve this contradiction by requiring that thick disk stars become younger in the disk outskirts.

“With our new understanding of the formation of, and interplay between, galactic thin and thick disks, we have moved much closer to solving one of the most fundamental problems of Galactic astrophysics.”, concludes Ivan Minchev. “Our predictions will soon be tested with data from the Gaia space mission and using high precision instruments, such as MUSE on the Very Large Telescope.”

On the formation of galactic thick disks, Minchev et al. 2015, ApJL, 804, L9.

 

Science contact: Dr. Ivan Minchev,+49 331 7499-454, iminchev@aip.de

Media contact: Dr. Janine Fohlmeister, +49 331 7499-383, presse@aip.de

 

The key topics of 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. Since 1992 the AIP is a member of the Leibniz Association.

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First Light for PEPSI

Spectrum of HD 82106 in comparison to other AIP observatories.

First Light for PEPSI

22 April 2015. The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) has received its first celestial light through the Large Binocular Telescope (LBT). Astronomers from the Leibniz...

On April 1st, the 2 x 8.4m mirrors of LBT, effectively an 11.8m telescope, were turned to the K3 dwarf star HD 82106, and PEPSI received its first celestial photons through the world’s largest telescope. The instrument splits the stellar light into a spectrum with a wavelength resolution otherwise only obtainable in solar physics. The commissioning team of four AIP astronomers on the 3200m Mt. Graham in Arizona was preceded by a team of five who prepared the instrument for this event.

The star was only the first in a series of commissioning targets that test the instrument’s resolving powers at different wavelengths. Switching between resolution modes or between wavelength settings takes less than a minute and can be done any time. PEPSI is the only instrument that enables astronomers to point to bright stars as well as to faint quasars during the same night.

 

 

 

Caption: Star spectrum of HD 82106 compared to the Sun and Arcturus (detail).


Science Contact and Principal Investigator: Prof. Dr. Klaus G. Strassmeier

Project scientists: Dr. Ilya Ilyin and Dr. Michael Weber

Media contact: Dr. Janine Fohlmeister, +49 331 7499 383

The key topics of 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. Since 1992 the AIP is a member of the Leibniz Association.

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Stars with the chemical clock on hold

Artist impression of red giant stars in the Milky Way. (credit: AIP/ J. Fohlmeister)

Stars with the chemical clock on hold

10 April 2015. An international team of astrophysicists, led by Cristina Chiappini from the Leibniz Institute for Astrophysics Potsdam, has discovered a group of red giant stars for which the ‘ch...

The term ‘Galactic Archaeology’ was coined to describe the fact that the Milky Way’s history is encoded not only in the quantities of various chemical elements seen in the spectra of stellar atmospheres (abundances), but also in stellar motions. One of the pillars of Galactic Archaeology is the use of stellar abundance ratios as an indirect estimator of age. While massive stars that explode as core-collapse supernovae mainly enrich the interstellar medium with oxygen and other ‘alpha elements’ on short timescales, Type Ia supernovae produce the bulk of iron and die after a longer time. The time delay between interstellar medium enrichment in alpha elements and iron can then be used as a chemical clock. Indeed, the chemical clock has been shown to work for many stars.

However, the authors of the new study demonstrate that alpha/iron enhancement is no guarantee that a star is in fact old. It has only recently become possible to determine precise ages for these stars, thanks to asteroseismology. This method measures pulsation frequencies, providing additional information about the age of stars. The group of stars studied appears to be relatively young, despite being enriched with alpha elements with respect to the Sun. Interestingly, these stars were found to be more abundant towards the inner Galactic disc regions where the interplay between the bar and spiral arms may lead to a more complex chemical enrichment scenario.

“Although there were similar stars in previous surveys, they were not identified as such and only very few of them. This may explain why these stars have received little attention so far,” mused Friedrich Anders, Chiappini’s co-author.

“Future observations will provide more clues as to the origin of these stars and the complex chemical evolution of the Milky Way,” concluded Cristina Chiappini.

The new CoRoT-APOGEE (CoRoGEE) sample is the result of collaboration between APOGEE (a high-resolution infrared survey) ‒ part of the Sloan Digital Sky Survey III (SDSSIII) ‒ and the CoRoT red giant working group. This collaboration enabled hundreds of red giant stars to be followed up spectroscopically, providing seismic information in the CoRoT fields. At present, only CoRoGEE can explore the inner-disc regions and determine the age of its field stars.

Publication: Young [ α /Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?, Chiappini et al. 2015, A&A, 576, L12

 

Caption: Location of the red giants studied by CoRoGEE in the Milky Way. The red stars show the ones for which the chemical clock does not work. (Credit: F. Anders)

Science contact: Dr. Cristina Chiappini, cristina.chiappini@aip.de, +49 331 7499-454

Media contact: Dr. Janine Fohlmeister, presse@aip.de, +49 331 7499-383

 

The key topics of 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. Since 1992 the AIP is a member of the Leibniz Association.

Read more ...