Credit: ESA/Gaia/DPAC
Licence type: Attribution (CC BY 4.0)
Gaia is a mission to create the most accurate and complete multi-dimensional map of the Milky Way. This allows astronomers to reconstruct our home galaxy’s structure and past evolution over billions of years, and to better understand the lifecycle of stars and our place in the Universe.
Gaia’s Data Release 3 (Gaia DR3) contains new and improved details for almost two billion stars in our galaxy. The catalogue includes new information including stellar chemical compositions, temperatures, colours, masses, ages, and the speed at which the stars move towards or away from us (radial velocity). Much of this information was revealed by the newly released spectroscopy data, a technique in which the starlight is split into its constituent colours. The data also includes special subsets of stars, like those that change brightness over time.
Also new in this data set is the largest catalogue yet of binary stars, thousands of Solar System objects such as asteroids and moons of planets, and millions of galaxies and quasars outside the Milky Way.
Professor Nicholas Walton (Institute of Astronomy, University of Cambridge, and member of the ESA Gaia Science Team) comments: “The Gaia: UK team at the University of Cambridge, University College London, University of Edinburgh, University of Leicester, and University of Bristol have played an essential part in this third data release providing the photometric data content – data obtained from light measurements. This release represents a major step forward in our creation of a detailed census of our Milky Way, fully characterising a significant sample of its stellar constituents. Analogous to the 100,000 Genomes project in biology, we are now able to characterise hundreds of millions of stars, which enables us to accurately determine their life cycles from birth to death, and to understand the incredible history and future of our Milky Way.”
Dr George Seabroke (UCL Mullard Space Science Laboratory) said: “Gaia’s chemical mapping is analogous to sequencing the DNA of the human genome. The more stars we know the chemistry for, the better we can understand our galaxy as a whole. Gaia’s chemical catalogue of six million stars is ten times larger than previous ground-based catalogues, so this is really revolutionary. Gaia’s data releases are telling us where stars were located and how they are moving. Now we also know what a lot of these stars are made of.”
“Unlike other missions that target specific objects, Gaia is a survey mission. This means that while surveying the entire sky with billions of stars multiple times, Gaia is bound to make discoveries that other more dedicated missions would miss. This is one of its strengths, and we can’t wait for the astronomy community to dive into our new data to find out even more about our galaxy and its surroundings than we could’ve imagined,” says Timo Prusti, Project Scientist for Gaia at ESA.
President of the Royal Astronomical Society, Professor Mike Edmunds, comments on the release: “The GAIA mission is based on brilliantly simple principles, used in astronomy for many years, but brought bang up-to-date by clever modern technology. The surveys it is doing are revolutionising many fields of research, for example the detailed archaeology of our own stellar system, the Milky Way. I am very much looking forward to hearing about the latest results.”
Source: Royal Astronomical Society (RAS)/News
Science Contacts
Dr Nicholas Walton
Institute of Astronomy
University of Cambridge
Tel: +44 (0)1223 337503
naw@ast.cam.ac.uk
Dr Francesca De Angeli
Institute of Astronomy
University of Cambridge
Tel: +44 (0)1223 337546
fda@ast.cam.ac.uk
Dr Dafydd Wyn Evans
Institute of Astronomy
University of Cambridge
Tel: +44 (0)1223 764608
dwe@ast.cam.ac.uk
Dr George Seabroke
Mullard Space Science Laboratory
University College London
Tel: +44 (0)1483 204902
g.seabroke@ucl.ac.uk
Media Contacts:
Robert Massey
Royal Astronomical Society
Tel: +44 (0)20 7292 3979,
Mob: +44 (0)7802 877 699
massey@ras.org.uk
Gurjeet Kahlon
Mob: +44 (0)7802 877700
Royal Astronomical Society
gkahlon@ras.ac.uk
Further information
Starquakes
- One of the most surprising discoveries coming out of the new data is that Gaia is able to detect starquakes – tiny motions on the surface of a star – that change the shapes of stars, something the observatory was not originally built for.
- Previously, Gaia already found radial oscillations that cause stars to swell and shrink periodically, while keeping their spherical shape. But Gaia has now also spotted other vibrations that are more like large-scale tsunamis. These nonradial oscillations change the global shape of a star and are therefore harder to detect.
- Gaia found strong nonradial starquakes in thousands of stars. Gaia also revealed such vibrations in stars that have seldomly been seen before. According to current ideas, these stars should not have any quakes, but Gaia did nonetheless detect them on their surfaces.
Stellar Fingerprinting: classifying the stars in our Milky Way
- What stars are made of can tell us about their birthplace and their journey afterwards, and therefore about the history of the Milky Way. With today’s data release, Gaia is revealing the largest chemical map of the galaxy coupled to the 3D motions of stars, from those in our solar neighbourhood to stars in smaller galaxies around our own.
- Some stars contain more ‘heavy metals’ than others. During the Big Bang, only light elements were formed (hydrogen and helium). All other heavier elements – called metals by astronomers – are built inside stars. When stars die, they release these metals into the gas and dust between the stars, out of which new stars form. Active star formation and death will lead to an environment that is richer in metals. A star’s chemical composition is a bit like its DNA, giving us crucial information about its origin.
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With Gaia, we see that some stars in our galaxy are made of primordial material, while others like our Sun are made of matter enriched by previous generations of stars. Stars that are closer to the centre and plane of our galaxy are richer in metals than stars at larger distances. By looking at their chemical composition, Gaia was also able identify stars that originally came from different galaxies than our own.
- What stars are made of can tell us about their birthplace and their journey afterwards, and therefore about the history of the Milky Way. With today’s data release, Gaia is bringing us a chemical map of the galaxy.
- Some stars contain more ‘heavy metals’ than others. During the Big Bang, the only stable elements to form were hydrogen and helium and traces of lithium. All other heavier elements – metals – are built inside stars. When stars die, they release these metals into the gas and dust between the stars, out of which new stars form. Active star formation and death will lead to an environment that is richer in metals. Therefore, a star’s chemical composition is a bit like its DNA, giving us crucial information about its origin.
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With Gaia we see that some stars in our galaxy are made of primordial material, while others like our Sun are made of matter enriched by previous generations of stars. Stars closer to the centre and plane of our galaxy are richer in metals than stars at larger distances.
- ESA’s Gaia data release 3 also shows us the speed at which more than 30 million Milky Way stars move towards or away from us. This is called ‘radial velocity’ and it is providing the third velocity dimension in the Gaia map of our galaxy. Together with the proper motions of stars (movement across the sky), we can now see how the stars move over a large portion of the Milky Way.
- This sky map shows the velocity field of the Milky Way for ~26 million stars. The colours show the radial velocities of stars along the line-of-sight. Blue shows the parts of the sky where the average motion of stars is towards us and red shows the regions where the average motion is away from us. The lines visible in the figure trace out the motion of stars projected on the sky (proper motion). These lines show how the direction of the speed of stars varies by galactic latitude and longitude. The Large and Small Magellanic Clouds (LMC and SMC) are not visible as only stars with well-defined distances were selected to make this image.
Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO.
Asteroid populations
Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO.
Notes for editors
More details on Gaia’s data releases 3 can be found here: https://www.cosmos.esa.int/web/gaia/data-release-3
From 13 June 2022, 12:00 CEST onwards, the new Gaia data can be accessed at https://gea.esac.esa.int/archive/
This media kit from ESA summarises the data in a series of infographics: https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_data_release_3_media_kit
More in-depth stories on the new Gaia data can be found here: https://www.cosmos.esa.int/web/gaia/dr3-stories
Gaia’s data release 3 will be presented on Monday 13 June during a virtual media briefing at a Royal Astronomical Society hosted event at Goonhilly Earth Station, and will be available on the RAS YouTube channel at https://youtu.be/rjCaRSJMIhc (The UK event presentation slides will be available at https://www.gaia.ac.uk/gaia-dr3-uk-event ).
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