Almost two billion stars for the new sky atlas obtained with Gaia

Almost two billion stars for the new sky atlas obtained with Gaia

We are used to thinking in terms of gigabytes. Our smartphones have 32 GB of internal memory. Our PCs have 1000 GB hard drives. But now mark this new size: 1.5 petabytes, or 1.5 million gigabytes. An absurd amount of data, incredible only to imagine. These are the data of the new stellar catalog released by ESA and obtained thanks to the observations of the Gaia mission.

The Gaia mission was launched in December 2013 and started observations the following year. Thanks to a tireless work lasting 22 months, ESA has been able to create a new stellar catalog containing information, such as position and speed, of 1.7 billion stars within a radius of 13,000 light years from Earth. In addition to the stars, the Gaia satellite has cataloged 14,000 new asteroids and 0.5 million quasars. It seems a lot of celestial bodies but in reality, the stars listed by Gaia are just 1% of those present in the Milky Way. Just to remind us of our dimension in the vastness of the Universe.

The result of this incredible work is a very accurate 3D map of the galaxy, which will allow us to study more accurately the dynamics of the Milky Way, the distribution of stars and their evolution.

Italy has played an important role in the success of this mission. In fact, both INAF and the Italian Space Agency participate in the Data Processing and Analysis Consortium.

Mario Lattanzi, of the INAF and responsible for our project country, commented:


Finally we not only know the surroundings of the solar system better but we start to dive into the vast spaces of the Milky Way, with astrometric errors at best of the 50 millionths of a second of arc, equivalent to the apparent size of an apple placed on the Moon, the evolutionary history of the Our Galaxy and its populations will have no more secrets within a radius of 13,000 light years from the Sun. In short, with DR2 Gaia becomes of age and provides the scientific world with its first dynamic star map totally based on the data taken from its astrometric instruments. spectro-photometric.

The data collected by Gaia will be of inestimable value for astronomers in the coming years. Some stars were also measured surface temperature (161 million stars), radial velocity along the line of sight (7 million stars) and the effects of dust on the light emitted from the stars (87 million stars). Furthermore, thanks to the data collected by stars within 5,000 light years, it was possible to improve the Hertsprung-Russell diagram. In 2020 the release of a new data set containing the spectral data of the observed stars and a more complete catalog of asteroids is expected.

Gaia will also make an important contribution to the discovery of new extrasolar planets, thanks to its extremely sensitive instrumentation. In particular, Gaia will be able to discover planets as large as Jupiter and with a maximum orbital period of ten years. At the maximum possible observation distance, equal to about 200 parsecs, Gaia will be able to identify exoplanets up to three times Jupiter and distant from 2 to 4 UA from their star.

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