On April 25, the European Space Agency (ESA) published the second file for the Gaia mission, an astrometry mission aiming to create the most precise map of our galaxy, the Milky Way. This second catalogue, apart from the locations of 1,700 million stars, includes the distance, movement and color of more than 1,300 million stars in the Milky Way and the nearest galaxies.
A team from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), affiliated to the Institute of Space Studies of Catalonia (IEEC) has taken part in this second release. This group leads the work of the mission file, and has also participated in this work. Moreover, Barcelona is the headquarters of one of the five data centers of the mission, among which are the Barcelona Supercomputing Center (BSC) and Consorci de Serveis Universitaris de Catalunya (Catalan Consortium of University Services, CSUC). The BSC offers the resources to conduct a part of the operations during the mission. At the moment, the BSC has also a safety copy of all the data for the Gaia satellite.
The catalogue has been carried out with data obtained by the satellite over the first twenty-two months of the mission. The file with these data, which are published today, is open to the scientific community, amateur astronomers and the general public. Regarding the first catalogue, published in September 2016, the new data include movements and parallax, which enables having –for the first time- a three-dimensional map of the galaxy, analysing the movement of 1 % of the stars that build it, and studying the structure and movement of the surrounding spiral galaxies.
The most precise universe in motion
This second catalogue has the positions of more than 1,700 million stars, and the parallax –which provides distance-, own movements, and photometry –brightness and colors- of more than 1,300 million stars.
In addition, the catalogue has more than seven million stars with measurements of their radium speed (speed at which the star gets closer or far), 550,000 light curves of variable stars that allow a critical review of the Universe distance scale; astrometry and photometry measurements for 14,000 asteroids, and the temperature of 160 million stars. The Gaia satellite has also observed the position of extragalactic objects such as quasars and faraway galaxies.
The central file of the mission is managed at the European Space Astronomy Centre (ESAC, in Madrid). The obtained map has a precision of 40 microseconds of arc for the brightest stars, and 700 microseconds of art for the weakest ones, therefore being the most accurate sky map.
Gaia’s potential for science
Moreover, researchers from the Gaia consortium publish today six scientific articles in the journal Astronomy & Astrophysics, using these data. These articles show the potential of the new data to work on science. Gaia opens a new window for the studies on stellar physics and formation mechanisms and evolution of stars, from the Galaxy and the surrounding satellite galaxies. These enable researchers study the rotation of the Magellanic Clouds, two small galaxies that are in the Milky Way; as well as galaxies closer to the Andromeda and Triangulum galaxies. The analysis of the motion of stars in the Milky Way will enable researchers to set the distribution of dark matter in our galaxy, an essential piece to progress in the knowledge of its nature. Another application of the map built with data from Gaia is the fact that it will improve observation predictions on astronomical phenomena, such as a star eclipse by one of the small planets or asteroids in the solar system.
The Gaia satellite, sent to space in December 2013 by the European Space Agency, aims to create the most accurate map of the Milky Way. With precise measurements of the positions and motions of the stars in the Milky Way, it will answer doubts on the origin and evolution of our home galaxy. The satellite is at 1,5 million kilometres from the Earth. The mission, with a 5-year initial length, was recently extended until 2020. More than a billion astrometry measurements have been carried out so far.
The central file of the mission is carried out at the European Space Astronomy Center (ESAC), in Madrid.
Participation of the University of Barcelona
The team of ICCUB (UB-IEEC), led by Professor Jordi Torra, from the Department of Quantum Physics and Astrophysics, and the tenured university lecturers Xavier Luri, Carme Jordi and Francesca Figueras, have taken part in the Gaia mission since the beginning, with an important role: they contributed to the scientific and technological design of the project and the prototype of the system for the astrometry data treatment, and have led the production of simulated data during the preparation phase of the mission.
Regarding the data to be published now, the team of Barcelona is leading the group that works on the file of the mission. They are also in charge of the initial process for the treatment of data that arrive to the satellite every day, the first step to get scientific results such as the ones to be published now. The group is also in charge of the pairing process for the different observations of a star, and collaborates with the calibration of star brightness and takes part in the scientific data exploitation.
The ICCUB Gaia team (UB-IEEC), formed by twenty scientists and engineers, was awarded in 2013 the Premi Ciutat de Barcelona to Experimental Sciences and Technology. The team is integrated in the Data Processing and Analysis Consortium (DPAC), which gathers more than 400 people from twenty European countries, and leads the creation of the file. Some of its members are part of the Gaia Science Team (GST), ESA’s scientific advisor body.
More information about the Gaia Mission at the ESA website.