ESA has published the second 3D map of the Milky Way and neighbouring galaxies obtained from the Gaia space probe, the most detailed of this type ever produced. This catalog, built thanks to what was called Data Release 2 (DR2), greatly expands the first map released by ESA in September 2016.
The Gaia space probe was launched on December 19, 2013 with the aim of creating a highly accurate 3D map of the Milky Way’s stars but also to catalog billions of other celestial objects, not only stars but also galaxies. Gaia began its scientific activity in July 2014, the first map included data collected until September 2015, the DR2 includes the following 8 months of observations.
The DR2 includes the location and brightness of 1,692,919,135 stars and information on distance, motion and color of more than 1.3 billion stars, with different numbers for each piece of data. There are also other information and parameters for small subsets of stars and other celestial objects, also included in the mapping by Gaia.
Gaia’s observations allowed to increase information on interstellar dust. These are also important because many parts of the Milky Way are obscured by clouds of gas and dust, but having a good map of them it’s easier to choose the most suitable instruments to observe those areas to detect the electromagnetic frequencies that pass through them.
In addition to the Milky Way’s stars, Gaia has allowed to catalog the position and the brightness of half a million quasars, about twice that of those listed in the first catalog. Quasars are typically very distant objects, sometimes even billions of light years, which are points of reference in the mapping carried out by Gaia so it’s important to have precise information about them.
The extra time considered for the purposes of DR2 allowed to further observe the trajectory of millions of celestial objects and thus improve the their speeds’ mapping. The new catalog also includes just over 14,000 objects in the solar system, especially asteroids, increasingly under observation after astronomers realized in recent years that there’s often an asteroid passing close to the Earth.
The top image above (Acknowledgement: Gaia Data Processing and Analysis Consortium (DPAC); A. Moitinho / A. F. Silva / M. Barros / C. Barata, University of Lisbon, Portugal; H. Savietto, Fork Research, Portugal) shows the map of the sky seen by Gaia in the DR2, the bottom image (Acknowledgement: Gaia Data Processing and Analysis Consortium (DPAC); Top and middle: A. Moitinho / A. F. Silva / M. Barros / C. Barata, University of Lisbon, Portugal; H. Savietto, Fork Research, Portugal;Bottom: Gaia Coordination Unit 8; M. Fouesneau / C. Bailer-Jones, Max Planck Institute for Astronomy, Heidelberg, Germany.) shows maps of color and total brightness at the top, of the density of stars at the center and of the interstellar dust in the Milky Way at the bottom.
The DR2 represents a significant step forward but it’s far from the end because new catalogs will be released in the coming years. They will be useful in astronomy research, in particular any research about the Milky Way and its stars but also for many other types.