Institute of Astronomy

Gaia mission releases 3D census of over 1 billion stars

Published on 24/04/2018 

The European Space Agency's Gaia mission has released its second batch of data. This release includes information on 1.7 billion objects (including stars, galaxies, quasars, and asteroids). This dataset covers a volume of space 1000 times greater than the previous Gaia release, with a hundredfold improvement in precision. This data will benefit almost all branches of astronomy, shedding light on the formation of our Solar System, the evolution of stars, the history of the Milky Way, the distribution of dark matter, and the calibration the Universe's distance scale.

The Gaia satellite was launched in December 2013 for a planned 5 year mission, aiming to complete a full-sky survey of positional and photometric data for a billion stars. This new data release provides the first demonstration of Gaia's abilities, and the early results are already spectacular.

In the new dataset a total of 1.3 billion objects have their brightnesses and colours accurately measured. The brightest 160 million objects will have their astrophysical parameters estimated, and 500,000 variable stars have also been observed, giving us a detailed window into their evolution (and allowing us to test the calibration of our Universe's distance scale).

7 million stars in the survey have both their spatial positions and their velocities carefully measured. This '6 dimensional' data (their position in 3D space, plus their 3D motions) will allow astronomers to calculate how these stars are orbiting around the centre of our Milky Way galaxy. This will let us weigh our galaxy more accurately than ever before, as well as mapping the distribution of (and possibly even helping us to better understand) dark matter.

Several members of staff at the Institute of Astronomy (IoA) have taken major roles in this release, working in close collaboration with other groups dedicated to other aspects of the project. Prof. Gerry Gilmore is 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.  Dr. Francesca De Angeli is head of the Cambridge processing centre, and Dr. Nicholas Walton is a member of the ESA Gaia Science Team. Dr. Dafydd Wyn Evans leads the work which has successfully calibrated Gaia’s brightness measurements to one part in a thousand, by far the highest precision data set of this scale ever produced. Dr. Floor van Leeuwen has been Project Manager for the UK and European photometric processing work.

A very special aspect of the Gaia mission is that the data will immediately become publicly available for anyone to download and analyse. "All this is made freely available to everyone, based on the dedicated efforts of hundreds of people. There are so many exciting things to do better with the exquisite Gaia data we anticipate new science papers appearing every day after this release" said Prof. Gilmore.

The Gaia science team has published several illustrative 'example papers' as tutorials for the community, and to illustrate the remarkable accuracy and volume of the data. Dr. Floor van Leeuwen is a leading co-author on the example science papers illustrating Gaia’s impact on our knowledge of star clusters and satellite galaxies in the outer Milky Way. This analysis, enabled by the new dataset, shows that groups of dwarf galaxies (including the Magellanic Clouds) can be seen to move in very similar orbits, suggesting a shared formation. In addition, these papers show that mapping the motions of objects orbiting the Milky Way (including dwarf galaxies and globular clusters) has allowed astronomers to create a 'mass map' of our galaxy at an unprecedented level of detail and accuracy.

As impressive as this data release is, there is still more to come from Gaia. Prof Gilmore commented "This is a great leap for mankind, but is still an early step. Gaia is continuing to observe, recently reaching its one trillionth measurement. The spacecraft has fuel for another 6-7 years operation, allowing a 10-year operational lifetime. This data set includes 22 months of data. This is a magnificent harvest, but a cornucopia awaits. We are all proud to be part of this magnificent project.”

Based on the Gaia DR2 press release.

Local IoA Cambridge contacts:  
Prof Gerry Gilmore gil@ast.cam.ac.uk,  44(0)1223337506, +447712774522
Dr Floor van Leeuwen fvl@ast.cam.ac.uk,  +44(0)1223766654
Dr Nic Walton  naw@ast.cam.ac.uk,  +44(0)1223337503
Dr Francesca De Angeli fda@ast.cam.ac.uk,  +44(0)1223337546
Dr Dafydd Evans dwe@ast.cam.ac.uk,  +44(0)1223764608

Links:
The ESA Gaia main page           https://www.cosmos.esa.int/web/gaia/home
The UK Gaia main page             https://gaia.ac.uk/
The Gaia archive                       http://gea.esac.esa.int/archive/

 

Figure: (click to get higher-resolution version)

 

This image shows the orbital tracks of 75 Globular Clusters (blue, covering 10 million years) and 9 Dwarf Galaxies (red, covering 100 million years). Proper motions for these systems, calculated using Gaia data, are 10 to 100 times more accurate than earlier results. This allows astronomers to reconstruct their true orbits far more accurately, shedding light on families of objects with a shared formation history. (Figure courtesy of M.Breddels and A.Helmi, Kapteyn Astronomical Institute, University of Groningen)

 

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Page last updated: 25 April 2018 at 11:06