A ‘tsunami’ for astrophysics: New Gaia data reveals the best map of our galaxy yet

Astronomers were hit today (Dec. 3) with a huge wave of data from the European Space Agency’s Gaia space observatory.

Those researchers can now explore the best-yet map of the Milky Way, with detailed information on the positions, distances and motion of 1.8 billion cosmic objects, to help us better understand our place in the universe. 

“Gaia data is like a tsunami rolling through astrophysics,” said Martin Barstow, head of the physics and astronomy department at the University of Leicester, who is part of Gaia’s data processing team. He was speaking at a virtual news conference held today, at which another Gaia researcher, Giorgia Busso of the Leiden Observatory in the Netherlands, also told reporters that this data has produced “a revolution” in many fields of astrophysics, from the study of galactic dynamics like stellar evolution to the study of nearby objects like asteroids in the solar system.

Photos: Gaia spacecraft to map Milky Way galaxy

Gaia launched in December 2013 to map the galaxy in unprecedented detail. The $1 billion spacecraft orbits the Lagrange-2, or L2, point, a spot about 1 million miles (1.5 million kilometers) away from Earth, where the gravitational forces between our planet and the sun are balanced and the view of the sky is unobstructed. Gaia can measure about 100,000 stars each minute, or 850 million objects each day, and can scan the whole sky about once every two months. 

The latest trove of data improves upon the precision and scope of the two previous Gaia data sets, which were released in 2016 and 2018. For example, compared to the 2018 data, which included measurements for 1.7 billion objects, the 2020 data improves by a factor of two the accuracy of the data points for proper motion, or the apparent change in the position of a star as viewed from our solar system.

“It really gives us an insight into how the Milky Way lives,” Nicholas Walton, an astronomer at the University of Cambridge who is part of Gaia’s science team, said at the same science and news conference. “We’re talking about billions of stars, which really gives us the ability to probe at a meaningful level the whole population of the Milky Way, similar to what you’d want to do with studying people.” 

Walton said the cosmic census would be like having trackers on every person in the U.K. to map their location and monitor their health. “If everyone’s got a tracker, we could tell you if they’re sweating or not. It’s a bit like that with the stars here: We can tell you which ones are sweating, which ones are active, which ones are dormant, which ones are going to die, which ones are going to explode.”

Data from Gaia has already been used across a wide range of applications over the past four years. The mission has helped researchers find the corpse of a galaxy that the Milky Way cannibalized 10 billion years ago, spot 20

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Gaia space telescope measures solar system’s acceleration

Gaia space telescope measures solar system's acceleration
The image shows the apparent motion of 3000 randomly selected, distant quasars caused by the acceleration of our solar system. For each quasar an arrow indicates the direction in which it is accelerated. Note how the motions appear to converge towards a point just below right of the direction to the centre of the Milky Way, which is in the image centre. The background shows Gaia’s all-sky view of our Milky Way Galaxy and neighbouring galaxies, based on the data released in the new EDR3 Gaia catalogue. Credit: ESA/Gaia/DPAC / CC BY-SA 3.0 IGO

The measurement of the acceleration of our solar system by astronomers of TU Dresden is a scientific highlight of the third Gaia catalog, which is now being released. With its publication on December 3, 2020, at 12:00 , the public will have access to high-precision astronomical data, such as positions, velocities, magnitudes and colors of about 1.8 billion astronomical objects.

What is Gaia? The aim of the ESA mission, launched on December 19, 2013, is nothing less than to produce a three-dimensional map of all astronomical objects that can be detected by the satellite’s 1000 megapixel camera—an impressive average of three million stars per hour. The observations are so accurate that Gaia could trace a motion of only a few centimeters for objects that are as far away as the Moon. An international team of scientists generates scientifically usable results from this enormous amount of observational data. This calculation, the iterative solution of a huge system of equations with 10 billion unknowns, has kept supercomputers in several European research institutions busy since 2015. Among those, TU Dresden’s high performance computers were heavily demanded by Prof. Klioner’s team to produce the numerous interim solutions which finally resulted in decisive improvements of the new Gaia products.

The excellent quality of these results enabled the scientists in Dresden to detect a highly interesting phenomenon: The acceleration of our solar system. In astronomy, it has been known for a while that such an acceleration causes a slow, apparent displacement of all astronomical objects, which should become noticeable as a global pattern in the measured motions. However, for nearby stars, this effect is completely superposed by the complex structure and dynamics of our galaxy.

Only a precise measurement of extremely distant astronomical objects, so-called quasars, could reveal this acceleration effect. These extremely luminous nuclei of distant galaxies are considered to be almost fixed on the sky, which is why they are used in astronomy as reference points.

The Dresden team identified about 1.6 million Gaia objects to be quasars, which will now be published as a Gaia own celestial reference system. These quasars clearly show the expected motion pattern of the extremely small acceleration, which, according to the results produced in Dresden, is 0.23 nanometers per second squared. It is the first time that this detection is obtained using optical observations. Professor Klioner explains:

“Measuring the acceleration of the solar system with a relative precision of 7 percent is a very

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