Personal tools

Sections
You are here: Home
Print this  

News

1.69 billion stars

Gaia’s all-sky view of our Milky Way Galaxy and neighbouring galaxies, based on measurements of nearly 1.7 billion stars. Credit: ESA/Gaia/DPAC

1.69 billion stars

Derived from 22 months of observations, the much awaited second data release of the Gaia mission is now public. The Leibniz Institute for Astrophysics Potsdam (AIP) contributed to the common effort...

The second data release contains the position and brightness of 1 692 919 135 stars, as well as measurements of the parallax and proper motion of 1 331 909 727 stars. Parallax is a small motion in the apparent position of a star caused by the Earth's yearly orbit around the Sun and depends on its distance from us. Proper motion is caused by the movement of a star through the Galaxy.

The now published data release contains more astrometric information than any other catalogue and represents a huge leap forward with respect to the mission's first data release. For the first time, the Gaia catalogue also includes high accuracy three-band photometry, radial velocities and stellar atmospheric parameters. With this observational data the Gaia mission produces a precise 3D map of the Milky Way with positions and velocities.

“The AIP contributes to the Gaia data analysis with two software modules for the radial velocity spectrometer on board Gaia: a first look module for data verification and a module taking care of the background correction for the spectra” explains Katja Weingrill, Co-I of Gaia at AIP.“The first look software performs a daily data validation check. The background correction cleans the observed spectra from 'false' light arising from point sources and the diffuse background.”

The full Gaia data release 2 is available at https://gaia.aip.de. “Gaia will be a major leap forward in our understanding of the cosmos. There is hardly any field in astronomy that will not fundamentally change owing to this new Galactic census” says Matthias Steinmetz, PI of Gaia at the AIP. ”The Gaia data will also be correlated with the results by one of AIP's core projects, the RAVE Survey, which will allow an even more thorough determination of the properties and chemical compositions of the stars in this catalogue. RAVE will release its full data set in summer 2018”.

Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). Gaia was launched in December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. Gaia is measuring stars in our Milky Way and neighbouring galaxies at a level of accuracy never before achieved. The first data release was based on 14 months of  data and listed positions of 1.1 billion stars, but only two million parallaxes and proper motions, and no photometry, radial velocities or stellar parameters.

 

More information

Pressemitteilung der ESA: https://bit.ly/2vIIKIJ

Gaia Media Kit: https://bit.ly/2qZhlwJ

Gaia Data Center am AIP:  https://gaia.aip.de

 

 

Scientific contact at AIP

Prof. Dr. Matthias Steinmetz, 0331-7499 801, msteinmetz@aip.de
Dr. Katja Weingrill, 0331-7499 671, kweingrill@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.

Read more ...

Girls' Day/Future Day 2018 at AIP

On April 26, 2018, the Future Day will take place once again. On thisnationwide day of action, female students from the 5th grade onwards have the opportunity to gain insight into occupational fiel...

It gives young participants a chance to look over astrophysicists' shoulders and learn more about working in science. How is everyday life for an astrophysicist? Where do the questions come from whose answer researchers are looking for? Which steps are part of the research process?

At this year's Girls’ Day, employees of the AIP present their work, showcasing

current projects and answering the questions of the students. They learn more about the history and meaning of constellations, create their own star map and immerse themselves in the exciting world of galaxy research. They also look behind the scenes of the historic site of the observatory Babelsberg and look - in case of suitable weather conditions - even through the telescope in the sky.

The limited to twenty participants seats were booked out after a short time.

 

Media contact:

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

Further information:
Read more ...
Starry Night on April 19

Illustration of the Transiting Exoplanet Survey Satellite (TESS) in front of a lava planet orbiting its host star. Credit: NASA/GSFC

Starry Night on April 19

The Leibniz Institute for Astrophysics Potsdam (AIP) invites to the next Starry Night in Babelsberg on Thursday, April 19, 2018, starting at 7:15 pm with a public lecture of Engin Keles on "Exoplan...

The Earth - a unique planet like no other in our solar system, with thriving flora and fauna. But can be quite different! If you look at exoplanets (ie those outside our solar system), you see bizarre things: planets of fiery magma, which resemble hell; Planets of ice and colder than the Arctic; Planets that consist only of water or pure iron. In the end, the question is: is our Earth that houses life truly unique, or are there other "habitable" planets out there? In this talk we will try to approach an answer.

 

- What exactly does "habitable" mean and which other types of planets exist?
- How do we find them?
- Why is the search of Earth-like planets easier for smaller stars than for larger ones?
- Where exactly must we look for it in our galaxy?
- Which factors influence the habitability of a planet?
- When do future space missions start to search for Earth-like planets?
With the help of these questions we go on a journey to the stars and embark on the "search for the second Earth".

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

Read more ...
Hide and Seek: a Black Hole in a Giant Star Cluster

The centre of the globular cluster NGC 3201, as seen with the MUSE-instrument at the ESO-VLT. The arrow marks the star with the high velocity, which indicates the presence of a Black Hole. Credit: Sebastian Kamann and the MUSE collaboration

Hide and Seek: a Black Hole in a Giant Star Cluster

17 January 2018. Astronomers, under the lead of the Georg-August-Universität Göttingen and with participation of the Leibniz-Institut für Astrophysik Potsdam (AIP) using ESO’s MUSE instrument ...

Globular star clusters are huge spheres of tens of thousands of stars that orbit most galaxies. They are among the oldest known stellar systems in the Universe and date back to near the beginning of galaxy growth and evolution. More than 150 are currently known to belong to the Milky Way.

One particular cluster, called NGC 3201 and situated in the southern constellation of Vela (The Sails), has now been studied using the MUSE instrument on ESO’s Very Large Telescope in Chile. An international team of astronomers, led by the University Göttingen and with researchers from AIP, has found that one of the stars in NGC 3201 is being flung backwards and forwards at speeds of several hundred thousand kilometres per hour, with the pattern repeating every 167 days.

Lead author Benjamin Giesers (Georg-August-Universität Göttingen, Germany) was intrigued by the star’s behaviour: “It was orbiting something that was completely invisible, which had a mass more than four times the Sun — this could only be a black hole! The first one found in a globular cluster by directly observing its gravitational pull.”

The relationship between black holes and globular clusters is an important but mysterious one. Because of their large masses and great ages, these clusters are thought to have produced a large number of stellar-mass black holes — created as massive stars within them exploded and collapsed over the long lifetime of the cluster.

ESO’s MUSE instrument (developed and built by Göttingen and Potsdam, amongst others)  provides astronomers with a unique ability to measure the motions of thousands of far away stars at the same time. With this new finding, the team has for the first time been able to detect an inactive black hole at the heart of a globular cluster — one that is not currently swallowing matter and is not surrounded by a glowing disc of gas. They could estimate the black hole’s mass through the movements of a star caught up in its enormous gravitational pull.

From its observed properties the star was determined to be about 0.8 times the mass of our Sun, and the mass of its mysterious counterpart was calculated at around 4.36 times the Sun’s mass — almost certainly a black hole.

Peter Weilbacher, one of the co-authors from AIP and in charge of the data reduction software for MUSE, is delighted: “A few years ago, the development of the detection methods started with a predecessor instument (PMAS) in Potsdam. With this discovery, the project has yielded a spectacular result.”

There is also an interesting historical connection to this discovery. “In 1915, Karl Schwarzschild was the first person to find a solution of the field equations of Einstein – at the time just a theoretical construct for what we call a black hole today. Also, Schwarzschild was head of the Göttingen observatory, before he became director at the Astrophysical Observatory  Potsdam”, Martin Roth explains the historical connections between the German partner institutes.

The development of MUSE and the research about the globular clusters at Potsdam and Göttingen is supported by the BMBF Verbundforschung.

 

Links:

Scientific article: Giesers et al. 2017

ESO webpage for MUSE instrument at VLT: MUSE | ESO

AIP webpage for MUSE: Development of the MUSE integral field spectrograph

Press release, images and movies at ESO: http://www.eso.org/public/germany/news/eso1802/

 

Scientific contacts at AIP:

Prof. Martin M. Roth, 0331-7499 313, mmroth@aip.de
Dr. Peter Weilbacher, 0331-7499 667, pweilbacher@aip.de
Prof. Lutz Wisotzki, 0331-7499 532, lwisotzki@aip.de

 

Press contact:

Dr. Janine Fohlmeister, 0331-7499 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.

Read more ...
First PEPSI data release

Illustration of PEPSI atlas. Credit: AIP/K. Riebe, spectra: PEPSI, background: J. Rendtel

First PEPSI data release

9 January 2018. The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first batch of high-spectral resolution data to ...

Spectral atlases are the fingerprints of stars and give insights into almost all of their physical properties like temperature, pressure, velocities and chemical composition. The first paper contains a new spectral atlas of the Sun and proves for the first time that a night-telescope instrument can reach a quality comparable to a specialized solar instrument. All solar and stellar spectra were taken with an unprecedented spectral resolution of λ/Δλ=250,000, a resolution equivalent to a 1/100th of the diameter of a hydrogen atom (λ being the wavelength and Δλ the smallest measurable separation of two wavelengths) and cover the entire optical and near-infrared light (from 383 to 914nm).

For the Sun several spectral time series with up to 300 individual spectra per day were pre-analyzed and are also provided to the community. "These data recover the well-known solar 5-minute oscillation at a peak of 3 mHz (5.5min) from the disk-averaged light with a radial-velocity amplitude of only 47 cm/s, an incredibly small velocity from a stellar point of view", says Prof. Strassmeier, PEPSI principal investigator and director of the Cosmic Magnetic Field branch at the Leibniz Institute for Astrophysics Potsdam (AIP). The new atlas was also used to re-determine the abundance of Lithium in the Sun with very high precision. "Lithium is a key element for the nucleosynthesis in the universe and is also a tracer of mixing processes inside stars", explains Dr. Matthias Steffen, one of the project scientists. Three-dimensional dynamic model atmospheres and a full statistical treatment of the spectral properties of the lithium atom were applied to determine the solar abundance.

The 48 stellar atlases in the second paper include the northern Gaia benchmark stars as well as other Morgan-Keenan standard stars. Spectra of these targets were not available at the given resolution and signal-to-noise ratio (S/N) before. The latter quantity represents the photon noise relative to the signal strength from the star and thus the quality of the spectra. Previously available S/N for work on astrophysical parameters was typically several hundred at a spectral resolution λ/Δλ of at most 100,000. "PEPSI and the LBT provide S/N of several thousand at on average three times higher spectral resolution", says Ilya Ilyin, PEPSI’s project scientist. "With such numbers we have now the typical daytime solar-like spectrum quality available also for bright stars at night time", adds Strassmeier.

Finally, in the third paper, the star "Kepler-444", hosting five sub-terrestrial planets, was confirmed to be 10.5 billion years old, more than twice the age of our Sun and just a little bit younger than the universe as a whole. The star is also found being poor on metals. The chemical abundance pattern from the PEPSI spectrum indicates an unusually small iron-core mass fraction of 24% for its planets if star and planets were formed together. For comparison, terrestrial planets in the solar system have typically a 30% iron-core mass fraction. “This indicates that planets around metal-poor host stars are less dense than rocky planets of comparable size around more metal-rich host stars like the Sun”, explains Claude “Trey” Mack, project scientist for the Kepler-444 observation.

AIP-scientists in the PEPSI project that led to the first data release include Michael Weber, Matthias Steffen, Silva Järvinen, Matthias Mallonn, Claude Mack, Thorsten Carroll, Carsten Denker, Sydney Barnes, Daniel Sablowski, Engin Keles, Ekaterina Dineva, Alessandro Mott, and Gohar Harutyunyan.


PEPSI Instrument

The PEPSI instrument at LBT. Credit: AIP

PEPSI Spektrum Esp Eri

The fingerprint of a star. Example from the new PEPSI atlases: the nearby planet-host star epsilon Eridani. Full resolution as pdf. Credit: AIP

PEPSI colored spectrum

Artificially colored spectrum of the solar twin star 18 Scorpii. Credit: AIP and M. Bergemann, MPIA

 

More information on PEPSI and the LBT:

https://pepsi.aip.de

http://www.lbto.org/

 

Online data viewer:

see "Library" at https://pepsi.aip.de

 

Original publications about the first data release in A&A:

K. G. Strassmeier, I. Ilyin, and M. Steffen, PEPSI deep spectra. I. The Sun-as-a-star, A&A, in press; arXiv:1712.06960

K. G. Strassmeier, I. Ilyin, and M. Weber, PEPSI deep spectra. II. Gaia benchmark stars and other M-K standards, A&A, in press; arXiv:1712.06967

C. E. Mack III, K. G. Strassmeier, I. Ilyin, S. C. Schuler, F. Spada, and S. A. Barnes, PEPSI deep spectra. III. A chemical analysis of the ancient planet-host star Kepler-444, A&A, in press; arXiv:1712.06986

 

Science contacts:

Prof. Dr. Klaus G. Strassmeier, 0331-7499-223, kstrassmeier@aip.de

Dr. Ilya Ilyin, 0331-7499-269, ilyin@aip.de

Christian Veillet (Large Binocular Telescope Observatory), +1 (520) 621-5286, cveillet@lbto.org

 

Media contact:

Dr. Janine Fohlmeister, 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 ...