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Starry Night on October 19

This red dwarf star (“Scholz's Star”) passed by the Sun 70,000 years ago in a distance of 10 light months. AIP researcher Ralf-Dieter Scholz discovered it in 2014. Credit: AIP, SuperCOSMOS Sky Surveys, WISE

Starry Night on October 19

The Leibniz Institute for Astrophysics Potsdam (AIP) invites to the next Starry Night in Babelsberg on Thursday, October 19, starting at 7:15 pm with a public lecture of Dr. Ralf-Dieter Scholz abou...

Even though the stars in the sky seem to be standing still, they are moving rapidly through space. This applies to our home star, the Sun, as well. However, the fast movement of stars is not visible to the naked eye, because even the nearest celestial bodies are far away from us. They do not crash into each other, not even if their paths cross or if a star that is drifting by is passing our solar system. Surprisingly, we are not even close to knowing all our neighboring stars, as Ralf-Dieter Scholz will explain in his talk. The closest star, Proxima Centauri, has only been discovered about a hundred years ago. The search for further hidden red dwarf stars and the brown dwarfs, which are even harder to find but also surround our Sun in great numbers, goes on.

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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The LBT gets polarized: First light for the PEPSI polarimeters

The Large Binocular Telescope at Mt. Graham, Arizona. Credit: Large Binocular Telescope Observatory

The LBT gets polarized: First light for the PEPSI polarimeters

Thanks to a cleverly designed "two-in-one" instrument attached to the world's most powerful telescope, astronomers can extract more clues about the properties of distant stars or exoplanets than pr...

Developed at the Leibniz-Institute for Astrophysics in Potsdam, Germany, the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) saw first light on April 1, 2015, after being successfully installed at the Large Binocular Telescope Observatory (LBTO) in Arizona, USA. Once both of PEPSI's polarimeters were mounted in the focus points of each of the LBT's two 8.4-meter mirrors in late September 2017, the telescope was pointed to the star gamma Equ and polarized light was received. From these spectra astronomers can, for example, deduce the geometry and strength of magnetic fields on the surfaces of distant stars, or study the reflected light from the atmospheres of potentially habitable exoplanets.

A polarimeter separates starlight according to its oscillation planes. It is complementary to a spectrograph that, like a prism, separates light according to its oscillation frequencies (or colour). The two combined, polarimeter and spectrograph, added to a powerful telescope, enable astronomers to obtain spectra in polarized light. This in turn allows the characterization of the full wave-front of the incoming stellar light and extract details of its radiation physics that otherwise remain hidden.

A series of integrations in circularly and linearly polarized light was obtained when the telescope was pointed to the magnetic reference star Gamma Equulei, or gamma Equ, a double star located about 118 light-years from Earth. These spectra have a spectral resolution of R=120,000, that means they can resolve two wavelengths only five hundredths of a hydrogen atom’s diameter apart. They cover two large wavelength regions in the visible light simultaneously, and have an unprecedented signal-to-noise ratio. Because the two polarimeters for each of LBT's "eyes" are identical and modular in design, circular and linear polarizations were obtained simultaneously.

The gamma Equ test also included a so-called null spectrum, which is obtained by swapping the observation sequence in the two fibers. Ideally, it would give zero polarization and be independent of wavelength. Any residual polarization would be due to instrumental effects.

“The null spectrum for PEPSI shows an extraordinary low degree of polarization noise caused by the instrument," says its principal investigator, Prof. Dr. Klaus Strassmeier, Research Branch Director at AIP and a professor of astronomy at the University of Potsdam. "Compared with the best spectropolarimeters currently available at other telescopes, it's probably better by a factor of ten." Eventually, the PEPSI polarimeters will enable stellar magnetic field measurements with extremely high precision," adds PEPSI’s project scientist Dr. Ilya Ilyin.

For Dr. Christian Veillet, LBTO Director, “In the 8-10m class telescope select club, PEPSI was already a unique instrument, thanks to its resolution coupled to two 8.4-m mirrors simultaneously available. The addition of a polarimeter on each of LBT’s eyes gives LBTO yet another unique capability. It comes as a precious complement to interferometry, which gives LBT's two eyes the imaging resolution of a 23-m telescope."

The PEPSI instrument is available to all LBT partners including the German astronomical community.

 

Polarimetric spectrum

Image 1 (pdf): First polarimetric spectrum from PEPSI. The target is the bright magnetic star gamma Equ. The black line is the PEPSI spectrum and the red line is, for comparison, the HARPS-Pol spectrum. From top to bottom: the magnetic null spectrum enlarged by a factor five, the normalized linear Stokes component U/Ic enlarged by a factor 5, the normalized linear Stokes component Q/Ic  enlarged by a factor 5, the normalized circular Stokes component V/Ic, and the normalized integral light I/Ic. Credit: Ilya Ilyin/AIP

Polarimeter1 Polarimeter2

Images 2ab: The two polarimeters SX (left side) and DX (right side) at the two LBT eyes. Credit: Klaus Strassmeier/AIP

 

More information about PEPSI:

pepsi.aip.de

 

More information about LBTO:

www.lbto.org

The LBTO blog: https://lbtonews.blogspot.com/2017/10/the-lbt-gets-polarized-first-light-for.html

 

Science contacts:

Prof. Dr. Klaus G. Strassmeier (Principal Investigator), +49 331-7499 223, kstrassmeier@aip.de

Dr. Ilya Ilyin (project scientist), +49 331-7499 269, ilyin@aip.de

 

Media contacts:

Katrin Albaum (AIP), +49 331-7499 803, presse@aip.de

Christian Veillet (Large Binocular Telescope Observatory),+1 520-349-4576, cveillet@lbto.org

 

The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona Board of Regents; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, The Leibniz Institute for Astrophysics Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia.

 

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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L'Oréal-UNESCO Fellowship for cosmologist Jenny Sorce

Foto: © Foundation L'Oréal | Carl Diner

L'Oréal-UNESCO Fellowship for cosmologist Jenny Sorce

To produce cosmological simulations and study our local neighbourhood in the Universe: The cosmologist Dr. Jenny Sorce received a fellowship of the L'Oréal-UNESCO For Women in Science programme. S...

Women account for only 28 percent of the world’s researchers, according to the UNESCO Science Report toward 2030, published in 2015. With the programme “For Women in Science”, the L’Oréal Corporate Foundation and the United Nations Educational, Scientific and Cultural Organization (in short: UNESCO) strive to support and recognize accomplished women researchers, to encourage more young women to enter the profession and to assist them once their careers are in progress.

Sorce is studying our cosmic home in a box, so to speak. She simulates “numerical boxes” filled with matter to model our local Universe’s formation and evolution, in order to understand the nature of 95 percent of its content that are still unknown. By means of supercomputers that compute the motion of matter, the boxes enable astrophysicists to reproduce the overall history of the Universe from its beginning until now. The part of the Universe we live in appears to be similar to the others, as it contains for example filaments filled with matter and voids – a cosmic web similar to a spider web. “However, when we look closer, this piece of the Universe differs from the others,” says Sorce. “This effect could be compared to looking at a zebra in a herd, among which it is indistinguishable, whereas its fur pattern has its own particularities if we study it in detail.” Thus, Sorce developed new “boxes” that resemble our local neighbourhood in the Universe and that are based on mathematical algorithms as well as astronomical observations, to which she contributed. She uses these boxes to understand our local environment and, also, to deduce its effect on global measurements when astrophysicists observe other parts of the Universe that are further away.

Sorce studied physics and astrophysics at the École normale supérieure de Lyon (ENS de Lyon), France, and did her PhD in astrophysics at the Universities of Lyon, France, and Potsdam. She was also spending a long-term research stay at the Institute for Astronomy at the University of Hawaii, USA. From 2014 to 2016, she worked as a Humboldt Research postdoctoral fellow. She was awarded the young researcher's prize of Lyon city in 2016.

Each year, the L’Oréal Corporate Foundation, in partnership with the French National Commission for UNESCO and the French Academy of Sciences, awards 30 fellowships to female researchers on the doctoral and postdoctoral level, who are working in the fields of life and physical sciences, and working or studying in France. Internationally, 275 female PhD students and Post-Docs receive one of the fellowships each year across 115 countries.

 

Original press release by the L’Oréal Foundation:

https://www.fondationloreal.com/categories/publications-284/lang/fr

 

Science contacts: Dr. Jenny Sorce, jsorce@aip.de

 

Media contact: 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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Perspectives of Astrophysics in Germany from 2017 to 2030

Presentation of the "Denkschrift 2017" at the annual meeting of the German Astronomical Society 2017. Full caption in the text. Photograph by: Thomas Klawunn

Perspectives of Astrophysics in Germany from 2017 to 2030

19 September 2017. At the annual meeting of the German Astronomical Society 2017, the Council of German Observatories presented the Denkschrift 2017 “Perspectives of astrophysics in Germany 2017-...

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.

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Solar eclipse in one hundred spectra

The partial eclipse as observed on Mount Graham in Arizona, USA. Image by: AIP/Ilya Ilyin

Solar eclipse in one hundred spectra

12 September 2017. A solar eclipse gives researchers the opportunity to observe parts of the sun that are normally invisible. With the Solar Disk Integrated Telescope (SDI) on Mount Graham in Ariz...

“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.

Read more ...