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Astronomers unveil secrets of giant elliptical galaxies

Velocity map of M87.

Astronomers unveil secrets of giant elliptical galaxies

12 September 2014 Davor Krajnović, astronomer at the Leibniz Institute for Astrophysics Potsdam (AIP), and his colleagues Eric Emsellem (ESO) and Marc Sarzi (University of Hertfordshire), have dis...

The three astronomers observed the giant galaxy M87 (NGC4486), which is the central galaxy in the Virgo cluster, and discovered that it displays some bulk rotation, albeit of a very low amplitude. The precision of MUSE allowed the team to reveal that the stars of M87 can move around its centre with average velocities of just 10-20 km/s. Equivalent to 36-72,000 km/h, this speed may seem very high, but for galaxies this is extremely slow.

Elliptical galaxies have long been considered as essentially being made up of old stars that move randomly within them, like a swarm of bees. This has been challenged in many instances in the past ten-twenty years, but giant elliptical galaxies are still considered as a nearly round and non-rotating group of old stars.

By showing that a "simple" galaxy like M87 can be quite complicated in the eyes of the new MUSE spectrograph, this result demonstrates the potential of this new instrument for further advancing our understanding of galaxies, and their formation. Davor Krajnović states: “MUSE has the capability to enhance our understanding of galaxies, how they form and develop. By using the MUSE velocity data to constrain simulation models, we might reach a whole new level of precision.” Their work is published in the Monthly Notices of the Royal Astronomical Society and a pre-publication version of the paper is available on arXiv: http://arxiv.org/abs/1408.6844.

The Multi Unit Spectroscopic Explorer (MUSE) is a 3D-spectrograph for the Very Large Telescope (VLT) of the European Southern Observatory at Paranal (Chile). MUSE features a complex optical system with the capacity to split and slice a field that measures one square arcminute on the sky into 90,000 spatial elements. For each point a spectrum is created, covering the optical and near infrared wavelength region of 465-930nm. AIP provides the Data Reduction Software and operates one of the data centres accessible to scientists from all over the world.

 

(Click to enlarge)

Left: Image of M87: Some small companions galaxies of this giant and round elliptical galaxy are visible to the right of the image. The red square delineates the field-of-view of the MUSE instrument, where the velocity of the central stars of M87 have been measured.

Right: A map for the average velocity of the stars in the central region of M87, divided in polygonal regions where the MUSE data have been combined to reach a sufficient quality for these measurements. After accounting that M87 as a whole is moving away from us, red or yellow bins show stars that on average are receding whereas blue or light azure bins show stars that on average are approaching. The MUSE map reveal a complex motion of the stars in M87, where stars move in one way in the central region and in another in its outskirts.

 

Further information:

 

Science contact: Dr. Davor Krajnović, +49 331-7499 237, dkrajnovic@aip.de

Media contact: Kerstin Mork , +49 331-7499 469, 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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Facets of Solar Magnetic Fields

High-resolution G-band images.

Facets of Solar Magnetic Fields

3 September 2014. Magnetic fields on the solar surface come in many shapes and sizes. The smallest magnetic flux elements become visible in the Fraunhofer G-band, a narrow spectral region with many...

Magnetic flux ropes generated in the solar interior can become buoyant and start to rise. When such a flux loop reaches the surface, a bipolar emerging flux region (EFR) appears in the photosphere. The EFR represents the intersection of the inverse U-shaped flux bundle with the solar surface. However, only a small fraction of sunspots grows beyond this stage and matures to develop a penumbra with a radial filamentary structure that surrounds the dark core of the sunspot. This umbra can contain bright umbral dots and dark umbral cores, which are separated by bright, elongated light-bridges. One of the prime objective of the newly commissioned 1.5-meter GREGOR solar telescope is to investigate the interaction of magnetic fields and plasma motions at the highest spatial and temporal resolution.

The “early science phase” of the GREGOR solar telescope started in May 2014 using the Grating Infrared Spectrograph (GRIS). The Leibniz Institute for Astrophysics Potsdam (AIP) is in charge of the GREGOR Fabry-Pérot Interferometer (GFPI), an imaging spectropolarimeter for high-resolution photospheric and chromospheric observations. AIP’s research group for Optical Solar Physics organized a 50-day observing campaign in July/August 2014, where all members and partners of the GREGOR consortium proposed scientific tasks, which were then jointly carried out by a team of experienced observers at Observatorio del Teide, Izaña, Tenerife. Data processing is in full swing and the initial outcome indicates excellent performance of telescope and instruments. First scientific results will be presented at the fall meeting of the Astronomische Gesellschaft in Bamberg on 2014 September 25/26 in a special forum dedicated to “High-Resolution Solar Physics”.

The 1.5-meter GREGOR solar telescope was built by a German consortium under the leadership of the Kiepenheuer Institute for Solar Physics in Freiburg with the Leibniz Institute for Astrophysics Potsdam, the Institute for Astrophysics Göttingen, and the Max Planck Institute for Solar System Research in Göttingen as partners, and with contributions by the Instituto de Astrofísica de Canarias and the Astronomical Institute of the Academy of Sciences of the Czech Republic.

 

Picture
click to enlarge

High-resolution G-band images. bright points, pores, an emerging flux region, and a sunspot with umbral dots and light-bridges. The data were captured with the Blue Imaging Channel (BIC) of the GFPI in July 2014.

Movie: click

 

Media Contact: Kerstin Mork , +49 331 7499 469, 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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New Milky Way Maps from RAVE data

Detail: DIBs map.

New Milky Way Maps from RAVE data

15 August 2014. Using data from the RAVE survey, a large observation project initiated and led by the Leibniz Institute for Astrophysics Potsdam (AIP), an international team of astronomers has prod...

The maps and an accompanying journal article appear the issue of the journal Science on 15 August 2014. The researchers say their work demonstrates a new way of uncovering the location and eventually the composition of the interstellar medium, which refers to the material found in the vast expanse between star systems within a galaxy.

This material, including dust and gas composed of atoms and molecules are left behind when a star dies. They also become the building blocks of new stars and planets. Analyzing rainbow-colored bands of starlight that have passed through space gives astronomers important information about the makeup of the space materials that the light has encountered. In 1922, a grad student’s photographs yielded some dark lines indicating ‘missing’ starlight, which must have been absorbed by a yet unknown source. These features were called diffuse interstellar bands (DIBs). Since then, scientists have identified more than 400 of these diffuse interstellar bands, but the material that is causing these bands to appear and their precise location have remained a mystery.

The nature of this puzzling material is important to astronomers because of the clues it could give about the physical conditions and chemistry of these regions between stars, critical components in theories of how stars and galaxies are formed. Researchers have speculated that the absorption of starlight that creates these dark bands points to the presence of unusually large complex molecules, but the proof has remained elusive. More concrete clues should emerge from the new pseudo-3D maps of the DIB-material within our Milky Way Galaxy produced by the 23 scientists who contributed to the Science article.

The maps were assembled from data collected over a 10-year period by the Radial Velocity Experiment (RAVE). The survey provided the mapmakers in the current project with data related to 500,000 stars. The vast size of the sample enabled the mapmakers to determine the distances of the material causing the DIBs and thus how it is distributed throughout the Milky Way Galaxy.

“With the wide area coverage of the spectroscopic survey RAVE it was for the first time possible to map out the three dimensional distribution of the DIBs” said Matthias Steinmetz of the Leibniz Institute for Astrophysics Potsdam (AIP), principle investigator of the RAVE survey. “We could show that the complex molecules responsible for the DIB features can also be found at larger distances to the Galactic plane than it is the case for interstellar dust”.

Janez Kos and Tomaz Zwitter of the University of Ljubljana in Slovenia led the astronomy team that produced this paper.

RAVE is a multinational project with participation of scientists from Australia, Germany, France, UK, Italy, Canada, the Netherlands, Slovenia and the USA, coordinated by the Leibniz Institute for Astrophysics Potsdam (AIP), Germany. Funding of RAVE which guarantees extensive data, telescope and instrument access is provided by the participating institutions and the national research foundations.

 

Science Contact AIP: Prof. Dr. Matthias Steinmetz, msteinmetz@aip.de, +49 331 7499 381

 

Contact to first authors of the publication: Janez Kos, University of Ljubljana, janez.kos@fmf.uni-lj.si, +386 1 4766 507

 

Media Contact AIP / RAVE: Dr. Gabriele Schönherr / Kerstin Mork, presse@aip.de, +49 331 7499 469

 

Related links

The Radial Velocity Experiment (RAVE)

 

Movie [mp4, 1280x720, 14 MB]

Fly by movie showing the distribution of RAVE stars (based on the 4th data release, Kordopatis et al. 2013) compared to a model of the Milky Way disk. In blue are dwarf stars, in red the much brighter giant stars. (Credit: Gal Matijevic (visualisation), The RAVE Collaboration)

Map (click to enlarge):

Maps of the measured DIB absorption in respect to the area they cover in our galaxy.

 


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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The Sloan Digital Sky Survey Expands Its Reach

(Credits: Dana Berry / SkyWorks Digital, Inc. and SDSS)

The Sloan Digital Sky Survey Expands Its Reach

16 July 2014. Building on 14 years of extraordinary discoveries, the Sloan Digital Sky Survey (SDSS) has launched a major program of three new surveys, adding novel capabilities to expand its censu...

This new phase of SDSS will explore the compositions and motions of stars across the entire Milky Way in unprecedented detail, using a telescope in Chile along with the existing Sloan Foundation Telescope.

It will make detailed maps of the internal structure of thousands of nearby galaxies to determine how they have grown and changed over billions of years, using a novel optical fiber bundle technology that can take spectra of each different part of a galaxy at once.

Sloan will measure the expansion of the Universe during a poorly understood five-billion-year period of the Universe’s history when Dark Energy started to drive its expansion, using a new set of galaxies and quasars.

 

The new survey is a collaboration of more than 200 astronomers at more than 40 institutions on four continents and incorporates telescopes in both the Northern and Southern Hemispheres. With these two telescopes, the SDSS will be able to see the entire sky for the first time.

 

Based on a press release by the SDSS collaboration

More images and videos can be found at the SDSS website.

 

Science contact at the AIP: Prof. Dr. Matthias Steinmetz, msteinmetz@aip.de, +49 331 7499 381

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CosmoSim Database for cosmological simulations released

Website of the CosmoSim database.

CosmoSim Database for cosmological simulations released

23 June 2014. The CosmoSim database (www.cosmosim.org) has now been released after an intensive testing period. This service to the scientific community is the successor of the MultiDark database (...

It provides access to currently six cosmological simulations - including a highresolution resimulation of selected regions with hydrodynamics and star formation - which originate from different international projects in collaboration with the Leibniz Institute for Astrophysics Potsdam (AIP).

 

Outputs of cosmological simulations are typically stored at supercomputing centres with restricted access and encompass terabytes of data - too much to be downloaded by everyone. By providing the data via CosmoSim, scientists from all over the world are able to access the data, filter or combine the results directly on the server and use them for their own research.

The available data products include catalogues of dark matter halos, their inner properties, merging histories, information about the cosmic web and for selected snapshots even the raw particle distributions allowing for much deeper studies of dark matter halos and their environment. All the simulations and database tables are made available through a modern web interface. Additional features include an extensive documentation, along with some background on the database structure and selected images and movies for outreach purposes.

The increase in resolution for cosmological simulations has led to larger data volumes, with individual tables reaching sizes in the terabyte range. By exploring a new database technology, it is now possible to store and analyse snapshots from simulations with nearly 60 billion particles directly in the CosmoSim database.

The new database technology, the Spider engine for MariaDB/MySQL, allows to spread the data over many server nodes, and one head node, resulting in a distribution of the computational task over many server nodes. Several additional software components were developed by AIP’s E-Science team to enable transparent handling of parallel queries. Further, a job queue was implemented as a direct plugin for MariaDB/MySQL, so that even long running queries are permitted without stalling the servers.

CosmoSim utilizes the modern web framework Daiquiri, which was developed by the E-Science team during the recent years. It provides direct data access via an SQL query form, a database browser and SQL validation before sending the query to the server. An interface to Virtual Observatory tools like TopCat allows further quick investigations and processing of the retrieved results.

CosmoSim is based fully on open source technology. The modules developed by the E-Science team are available on GitHub at https://github.com/adrpar and https://github.com/jochenklar.

Demo movie:                      
http://www.cosmosim.org/cms/documentation/demos-and-tutorials/first-steps-with-cosmosim

 

The CosmoSim-Team:
- Kristin Riebe, kriebe@aip.de (data management and support)
- Jochen Klar, jklar@aip.de (web interface - backend and frontend)
- Harry Enke, henke@aip.de (management)
- Stefan Gottloeber, sgottloeber@aip.de (simulation data)
- Adrian Partl, apartl@aip.de (backend and database development)

 

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 ...