It’s Written in the Stars

Posted by ap507 at Apr 25, 2018 11:20 AM |
Data from Gaia mission will be like ‘a tidal wave through all of astronomy, transforming everything we know… or think we know about the Universe’

Issued by University of Leicester on 25 April 2018

ESA media kit available here:

Infographics from the project available here (Credit: ESA):

Astronomers today opened one of the last remaining windows on the Universe, publishing the first full 3D census of over one billion stars in our Milky Way.

The European Space Agency Gaia mission has provided the information for astronomers to map the true 3-dimensional structure of our Milky Way Galaxy, with over one billion stars having their positions and distances published to unprecedented precision. This is some 600 times more stars than previously available, covering a volume 1000 times larger than Gaia’s own first data release, with precision some one hundred times improved.

The University of Leicester has been part of the Gaia Data Processing and Analysis Consortium (DPAC) since the project started. Funding for the Leicester work has been running for some 15 years with Professor Martin Barstow as Principal Investigator.  Professor Barstow is Pro-Vice-Chancellor, Strategic Science Projects Director, Leicester Institute of Space & Earth Observation and Professor of Astrophysics & Space Science.

He said: “After 15 years of intense work, this new release of data from the ESA Gaia space mission will provide the most accurate map ever of the positions and distances of more than a billion stars in the Milky Way. Its impact will be like a tidal wave through all of astronomy, transforming everything we know… or think we know about the Universe.”

The University team has a critical role in the mission –they are responsible for understanding and compensating for radiation damage that affects the on-board sensors. If this isn’t done, all the critical science from the mission would be degraded. Professor Barstow also have a science interest, as Gaia observations of white dwarf stars will have a major impact on his research. He is a key contributor to one of the papers that will be released along with the data archive on 25 April.

The paper relates to the relation between the intrinsic brightness of a star and its colour (Hertzprung-Russell diagram) which can be mapped with Gaia’s exquisite measures of both parameters, illustrating the evolution of stars from birth to death. Professor Barstow is a senior co-author of this illustration science paper.

He said:  “The huge sample, accurate luminosities and colours, make visible for the first time features in stellar evolution which we have suspected but never seen. For example, we can now see directly the late evolution of stars, once they have ejected their envelopes and become dead cores – white dwarfs – cooling rapidly onto sequences which depend on the chemical element distributions, arising from the lifecycle of the parent star. This is superb confirmation of stellar theory, and has the precision and numbers to allow us to further refine and test our understanding of the end-point of stars like our own Sun.”

Others who have been involved over the years in the project while at Leicester are Claudio Pagani, Steve Sembay, Andy Read, Duncan Fyffe and Patricio Ortiz.

Researchers say these results allow improved study of almost all branches of astronomy: from traces of the formation of the Solar System; through how stars evolve; through the current structure, the assembly and evolutionary history of the Milky Way; to mapping the distribution of Dark Matter in the Galaxy; to establishing the distance scale in the Universe; to discovery of rare objects.

Gaia’s data achieve all this since it delivers not just 1.3billion distances and apparent motions across the sky.

Every star has very precise measures of its brightness and colours. Seven million stars have their line of sight (Doppler shift) velocities measured, providing full 6-dimensional – three space positions, 3 space motions – information, determining full orbits for those stars in the Milky Way. This is the information needed to weigh the Galaxy, and determine the distribution – and perhaps the properties – of Dark Matter, the mysterious substance which dominates the mass of the Galaxy and the Universe. 500,000 variable stars are published, allowing detailed precise analyses of how stars evolve and if our current calibration of cosmological distances is robust. 14,000 asteroid orbits are determined 100 times better than previously, testing the families of building blocks of Solar System formation.

A very special aspect of the Gaia mission is that the team of hundreds of engineers and scientists across Europe who have delivered the Gaia spacecraft and its data do not keep the results for their own science interests. The team processes and calibrates the data, and has published several illustrative analyses as tutorials for the community, and to illustrate the remarkable accuracy and volume of the data. Today’s release puts the Gaia data on a global level playing field with free access to everyone for analysis and discovery.

“The combination of all these unprecedented measures provides the information for astronomers to take the next big steps in mapping the formation history and evolutions of stars and our Milky Way Galaxy. There is hardly a branch of astrophysics which will not be revolutionised by Gaia data. The global community will advance our understanding of what we see, where it came from, what it is made from, how it is changing. All this is made freely available to everyone, based on the dedicated efforts of hundreds of people. There are so much exciting things to do better with the exquisite Gaia data we anticipate new science papers appearing every day after this release,” said Prof Gerry Gilmore, UK Principal Investigator for the UK participation in the Gaia Data Processing and Analysis Consortium, and one of the original proposers of the mission to ESA.

The UK has been a major partner in the Gaia mission since its proposal, with significant involvement in spacecraft design and construction, especially by Airbus Defence and Space (Stevenage), and through provision of the sensors for Gaia’s billion-pixel camera, by Teledyne-e2v (Chelmsford). Several UK teams have key roles in processing the data. Cambridge, supported by the UK Space Agency and STFC, hosts one of the six data processing centres with responsibility for the brightness, colour and spectrophotometry (for DR3) data.

Dr Francesca deAngeli, head of the Cambridge processing centre, commented: “This data release, which contains nearly 2 years of Gaia science data, has proven an exciting challenge to process from spacecraft camera images to science-ready catalogues. We have a dedicated team, a significant computing centre, and now a substantial and complex processing system to handle all the real-world complexity. Scientists in Edinburgh and Leicester work with us in Cambridge, and colleagues across Europe, to develop and test this complex system. We are delighted to be able to produce this all-sky map of beautiful data, and look forward to all the exciting science results. Gaia keeps observing, and has just reached one trillion observations. We are already busy processing the next year of Gaia’s data, ready for even more science and even more precise results to be released in another 2 years’ time, and even more after that.”



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