Carnegie Mellon University
April 26, 2018

Gaia Release Creates Richest Star Map of Our Galaxy Yet

Jocelyn Duffy

On a dark night, with the naked eye, one can see thousands of stars, all of which are in our Galaxy, the Milky Way. Determining the exact position of each star is limited by the angular resolution of the human eye, which is about an arcminute (1/30th the size of the moon). Standing in a field at night with no other tools does not allow us to say anything about how far each star is from us or how fast it is moving.

Over the last century, improving technology has enabled us to map not thousands, but millions of stars in the Milky Way with a precision far beyond that of an arcminute. Using a variety of techniques, astronomers also have determined the distances to many of these stars and even some of the velocities. On Wednesday, April 24, the Gaia satellite enabled us to push this program further than ever. The team, which counts CMU’s Sergey Koposov as one its members, released accurate positions, distances and velocities of 1.7 Billion stars.

The Gaia data ...

Prof. Sergey Koposov

Picking up data from the noise: Prof. Sergey Koposov

An excited Koposov, who is co-author on the papers released with the data, said “It is difficult to overestimate the expected impact of the Gaia data on many areas of Astrophysics: from stellar evolution to galactic dynamics, from finding black holes to mapping dark matter and establishing a cosmological distance ladder.” As just one example, the Gaia version of the canonical Hertzsprung-Russell Diagram that sorts stars by their luminosities and temperatures contains more than 100 times more stars than the previous chart.

Koposov emphasizes that this is only the beginning, as the whole astronomical community will be given access to this dataset, which is ten thousand times larger than its predecessor from Hipparcos. Multiple discoveries across many fields of astronomy should ensue. So, by all means, check out the work of Sergey and colleagues today, and look for the fruits of their labor to live on for years to come.

Gaia's Hertzsprung-Rusell diagram

The Gaia version of the Hertzsprung-Russell diagram