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Starry Night on October 18

A new season of the Babelsberg starry nights begins: On October 18, at 7.15 pm the Leibniz Institute for Astrophysics Potsdam (AIP) invites you to the first event after the summer break. Dr. Klaus ...

 

The beginnings of astrophysical research in Potsdam go back a long way. In the more than 300 years that have passed since the founding of the Royal Berlin Observatory - the predecessor institution of today's AIP - numerous well-known personalities, scientific highlights and historical events shaped the history of the institute. Which role played Gottfried Wilhelm Leibniz play in founding? How is Alexander von Humboldt connected to the observatory? Which traces left the turbulent 20th century? With the lecture at a historical site, Klaus Fritze invites to a journey through time and explains how Potsdam became the astronomical science location, that it is today.

 

After the talk, we offer a tour over the AIP campus and – if the sight is clear – an observation with one of our historical reflecting telescopes. 

We look forward to your visit!

Free entry, no previous registration necessary.

Location: AIP, An der Sternwarte 16, 14482 Potsdam

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Journey to the Beginning of Time

Pristine_221.8781+9.7844 and its surroundings. (Credits: N. Martin, DECALS survey, and Aladin)

Journey to the Beginning of Time

Potsdam, 8th October 2018. With the Pristine survey, an international team is looking for and researching the oldest stars in our Universe. The goal is to learn more about the young Universe right ...

When studying the early universe, astronomers have different methods at their disposal: One is to look to very large distances and therefore back in time, to see the first stars and galaxies as they were many billions of years ago. Another option is to examine the oldest surviving stars from our own Galaxy, the Milky Way, and use them to get a glimpse of what the conditions were like in the early Universe. The "Pristine" survey, led by Dr Else Starkenburg from the Leibniz Institute for Astrophysics Potsdam (AIP) and Nicolas Martin from the University of Strasbourg, is looking to do just that.

The scientists employ a special colour filter on the Canada-France-Hawaii Telescope to search for stars with relatively pristine atmospheres. In their recent publication they have used this technique to discover one of the most metal-poor stars known. Detailed follow-up studies with spectrographs of the Isaac Newton Group in Spain and the European Southern Observatory in Chile have demonstrated that the star has indeed very few heavy elements in its atmosphere. „The star contains less than one ten- thousandth of the metal content of the Sun. Additionally, its detailed pattern of different elements stands out. Whereas most metal-poor stars that exhibit such low levels of elements like iron and calcium also show a significant enhancement in carbon, this star does not. This makes it the second star of its kind ever discovered, and an important messenger from the early Universe“, says Else Starkenburg.

Finding these oldest messengers is no easy task, since they are quite rare among the overwhelming population of younger stars in our Galaxy. Just after the Big Bang, the Universe was filled with hydrogen and helium and a bit of lithium. No heavier elements were around, as these are generated in the hot interiors of stars – and those did not exist yet. Our Sun has about two percent of heavier elements in its atmosphere, as can be seen in the spectrum of its light. Because of this fact, astrophysicists can conclude that the sun has emerged as part of a later generation of stars - and is made up of "recycled" material from stars that lived long before it and have since died out.

In searching for the oldest stars, scientists look for stars with more pristine atmospheres than our Sun. The more pristine the atmosphere, the earlier the generation in which this star was born. Studying stars of different generations allows us to understand the history of the Galaxy - an area of research that is therefore also called Galactic archaeology. The existence of a class of metal-poor stars with low carbon abundances suggests that there must have been several formation channels in the early Universe through which long-lived, low-mass stars were formed.

 

The metal-poor star Pristine_221.8781+9.7844 and its surroundings. (Credits: N. Martin, DECALS survey, and Aladin)

 

This figure shows the spectrum for the star studied (in black), as well as a modelled spectrum for the Sun (in grey). The main features in the spectrum of Pristine 221.8781+9.7844 are hydrogen lines, very few other elements are imprinted in this spectrum, only a small amount of calcium. In the solar spectrum on the other hand we see many lines. This tells us that the star Pristine 221.8781+9.7844 is ultra metal-poor and has an unusual lack of heavier elements in its atmosphere, which means that it probably belongs to an early generation of stars formed in the Galaxy. (Credit: AIP/E. Starkenburg)

 

Scientific Contact Dr Else Starkenburg, 0331-7499 213, estarkeburg@aip.de

Media contact Franziska Gräfe, 0331-7499 803, presse@aip.de

Publication Monthly Notices of the Royal Astronomical Society (Oxford University Press) https://doi.org/10.1093/mnras/sty2276

 

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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The glowing Universe

Deep observations made with the MUSE spectrograph on ESO’s Very Large Telescope have uncovered vast cosmic reservoirs of atomic hydrogen surrounding distant galaxies. (Credit: ESO/Lutz Wisotzki et al.)

The glowing Universe

Using the MUSE spectrograph at the Very Large Telescope of the European Southern Observatory (ESO), scientists have uncovered vast cosmic reservoirs of atomic hydrogen surrounding distant galaxies....

Light travels astonishingly quickly, but at a finite speed, meaning that the light reaching Earth from extremely distant galaxies took a long time to travel, giving us a window to the past, when the Universe was much younger. As a result, the signals that can be received by such galaxies are correspondingly faint – this requires the world's largest telescopes with the best sensors to obtain usable data. MUSE, the instrument behind these latest observations, is a state-of-the-art integral field spectrograph installed at ESO's Paranal Observatory in Chile and partly developed and built by AIP. When MUSE observes the sky, it sees the distribution of wavelengths in the light striking each pixel in its detectors. Looking at the full spectrum of light from astronomical objects provides us with deep insights into the astrophysical processes occurring in the universe.

Of particular interest to astrophysicists is the light of the so-called Lyman-alpha spectral line, which is generated by cosmic hydrogen. Based on the MUSE observations of Lyman-alpha radiation from distant galaxies, the research team was able to prove that the hydrogen is not only to be found within the galaxies as expected, but that they are surrounded by very extensive hydrogen envelopes. Although the detected radiation is extremely faint, it is distributed so widely that practically every direction in the sky shows at least the outer area of such a hydrogen shell.

“Realising that the whole sky glows in optical when observing the Lyman-alpha emission from distant clouds of hydrogen was a literally eye-opening surprise,” explaines AIP scientist and team member Dr Kasper Borello Schmidt.

The observed region is an otherwise unremarkable area in the constellation of Fornax ("the Furnace"). In 2004 it was first mapped by the Hubble Space Telescope. Those observations revealed thousands of galaxies scattered across a dark sky, giving an impressive view of the universe. Thanks to MUSE, a closer look into this region was now possible. The study published in the journal Nature shows for the first time how this "cosmic glow" from the gas pockets of the earliest galaxies is distributed in the light of the Lyman-alpha radiation.

"With these MUSE observations, we get a completely new view on the diffuse gas 'cocoons' that surround galaxies in the early Universe," commented co-author Philipp Richter.

The spectacular discovery of the astronomers proves that such clouds of hydrogen exist and that they glow - albeit incredibly weak. However, the exact physical processes leading to the emission of this radiation are still not fully understood. But as the team has now shown, it is ubiquitous in the night sky, and future research is expected to shed light on its origin.

“In the future, we plan to make even more sensitive measurements,” concluded Lutz Wisotzki, leader of the team. “We want to find out the details of how these vast cosmic reservoirs of atomic hydrogen are distributed in space.”

 

Publication http://dx.doi.org/10.1038/s41586-018-0564-6

ESO Press Release https://www.eso.org/public/news/eso1832/

Nature shareable link https://rdcu.be/8iPO

arXiv publication https://arxiv.org/abs/1810.00843s

 

Leibniz Institute for Astrophysics (AIP)

Scientific Contact:                    Prof. Dr. Lutz Wisotzki, 0331-7499 532, lwisotzki@aip.de

Media Contact:                         Franziska Gräfe, 0331-7499 803, presse@aip.de

University of Potsdam

Scientific Contact:                    Prof. Dr. Philipp Richter, 0331-977 1841, prichter@astro.physik.uni-potsdam.de

Media Contact:                         Antje Horn-Conrad, 0331-977 1665, hconrad@uni-potsdam.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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Uncovering the birthplaces of stars in the Milky Way

Using precise stellar age and iron content measurements, the stellar birth places could be recovered. Credit: I. Minchev (AIP)

Uncovering the birthplaces of stars in the Milky Way

13 September 2018. An international team of scientists led by Ivan Minchev of the Leibniz Institute for Astrophysics Potsdam (AIP) has found a way to recover the birth places of stars in our Galaxy...

Stars in galactic discs have long been known to wander away from their birth sites owing to a phenomenon known as “radial migration”. This movement across the Galaxy severely hampers inferences of the Milky Way formation history. Radial migration is influenced by a number of parameters that are still poorly known: for example, the size and speed of the Galactic bar, the number and shape of spiral arms in the Galactic disc, and the frequency of smaller galaxies colliding with the Milky Way during the past 10 billion years and their respective masses.

To circumvent these obstacles, the scientists devised a way of recovering the Galactic migration history using the ages and chemical composition of stars as “Archaeological artifacts”. They used the well-established fact that star formation in the Galactic disc progresses gradually outwards, following that stars born at a given position at a particular time have a distinct chemical-abundance pattern. Therefore, if the age and chemical composition (its iron content, for example) of a star can be measured very precisely, it becomes possible to directly infer its birth position in the Galactic disc without additional modeling assumptions.

The team used a sample of about 600 solar-neighborhood stars observed with the high-resolution spectrograph HARPS mounted on the 3.6 m telescope of ESO’s La Silla Observatory in Chile. Thanks to the very precise age and iron abundance measurements, it was found that these stars were born all across the Galactic disc, with older ones coming more from the central parts.

Researches can now use this method for calculation of birth places even for stars not in the original sample. For example, given the age of our Sun of 4.6 billion years and its iron content, it could be estimated that the Sun was born about 2,000 light years closer to the Galactic center than it is currently located.

Minchev comments: “Once in the possession of birth radii, a wealth of invaluable information could be gained about the Milky Way past, even from this small number of stars with precise enough measurements available to us at this time.” Co-author Friedrich Anders adds: “In the near future, applying this method to the extremely high-quality data from the Gaia mission and ground-based spectroscopic surveys will allow much more exact measurements of the migration history and, thus, the Milky Way past.”

 


Left: A sample of about 600 stars situated very close to the Sun was used (approximate volume shown by arrow). Right: Using precise stellar age and iron content measurements, the stellar birth places could be recovered. Older stars were found to arrive preferentially from the inner parts of the disk (lighter coloured dots), while younger ones (darker coluored dots) were born closer to their current distance from the Galactic centre. The background image shows a simulation of a galaxy similar to the Milky Way for perspective. Credit: I. Minchev (AIP)


Scientific Contact

Ivan Minchev, 0331-7499-259, iminchev@aip.de

Media contact

Franziska Gräfe, 0331-7499 803, presse@aip.de

Publication

http://doi.org/10.1093/mnras/sty2033

 

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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In memoriam of Prof. Hans Oleak

On September 7, 2018, Prof. Hans Oleak passed away at the age of 88. The Leibniz Institute for Astrophysics Potsdam (AIP) mourns the loss of our esteemed colleague, who throughout his life shared h...

Hans Oleak studied physics with a focus on astrophysics at the Friedrich Schiller University Jena. In 1956 he started his scientific work at the Babelsberg Observatory in Potsdam. After graduating in the field of cosmology, he was appointed professor by the Academy of Sciences in 1981. He was head of department for the field of extragalactic research at the AIP and taught at the University of Potsdam, the Humboldt University and at the Technical University of Berlin. The astrophysicist was one of the co-founders of the European Astronomical Society in 1990 and one of the first members of the newly founded Urania Association in Potsdam in 1991.

 

Hans Oleak always shared his enthusiasm for astronomy with great dedication and it was important to him to pass on his knowledge in a comprehensible way. So he held numerous popular science lectures, organized teacher training and was the chief editor of the astronomical magazine "The Stars" from 1993 to 1996. In addition, he was involved as a board member and chairman of the URANIA Association Potsdam. He also shared his knowledge in books and television programs. In 2013, the City of Potsdam honored him for his commitment with the honorary office award. In March 2018 he received the Wilhelm Foerster Prize from Urania Potsdam.

Our condolences are to his relatives, his family, friends and all who were close to him.

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