European space telescope survey finds 400 million more stars in a section of the milky way previously known to have 700 million star

The Milky Way has been mapped in greater detail than ever before. And a first quick look indicates that our home galaxy is larger in extent than scientists had thought before, says Gisella Clementini, an astronomer at the Astronomical Observatory of Bologna in Italy.

Today, at the European Space Astronomy Centre in Madrid, the European Space Agency (ESA) released the first data from its €750 million Gaia star-mapping mission. The new catalog contains sky positions for 1.1 billion stars, 400 million of which have never been seen before. For many stars, the positional accuracy is 300 microarcseconds—the width of a human hair, seen from a distance of 30 kilometers—positions that will help astronomers better determine the 3D layout of the galaxy. “This is far better than anything we’ve ever had before,” says project scientist Timo Prusti of ESA’s science and technology center ESTEC in Noordwijk, the Netherlands. “It’s a milestone.”

A second data release, planned for late 2017, will include even more accurate positions—in some cases up to 10 microarcseconds, or a human hair at a distance of 1000 kilometers. The second release will also contain distances and motions for all 1.1 billion stars, says astronomer Anthony Brown of Leiden University in the Netherlands, who chairs a 450-member consortium of Gaia data analysts. In addition, Gaia will discover tens of thousands of new star clusters in the Milky Way, and yield accurate positional data for about a million remote galaxies. “Future facilities like the Large Synoptic Survey Telescope, the James Webb Space Telescope, and ESA’s Euclid satellite, will gratefully exploit the Gaia catalog,” Brown says.

The Milky Way is a barred spiral galaxy that has a diameter usually considered to be about 100,000–120,000 light-years but may be 150,000–180,000 light-years. The Milky Way has been estimated to contain 100–400 billion stars. The new survey would suggest the higher end of size and numbers of stars is likely correct.

In the future, Gaia is also expected to discover new asteroids in our solar system and thousands of Jupiter-like planets orbiting other stars.

Astronomers dream of an infrared counterpart to Gaia, which would be able to peer through the Milky Way’s dust cloud into its very center, and also would excel at detecting and measuring faint red and brown dwarf stars in the solar neighborhood.

SOURCES – Science Mag, Wikipedia