It is those last two properties that are particularly edifying for astronomers: before Gaia, scientists lacked high-precision measurements of the distance to many stars, as well as what’s known as proper motion, or a star’s movement across the sky. The mission aims to catalogue more than 1 billion local stars, charting their brightness, temperatures, ages, locations and velocities. Such monumental discoveries are becoming almost commonplace thanks to Gaia. “It’s just incredible to have been able to find such an important milestone in the history of the Milky Way,” says Helmi. It is the last-known major crash the Galaxy experienced before it assumed the familiar spiral shape seen today.Īlthough the signal of that ancient crash had been hiding in plain sight for billions of years, it was only through Gaia’s data set that astronomers were finally able to detect it. That beast once circled the Milky Way like a planet around a star, but some 8 billion to 11 billion years ago, the two collided, massively altering the Galactic disk and scattering stars far and wide. Within weeks, the team had worked out that the luminous horde pointed to a long-hidden and especially tumultuous chapter in the Milky Way’s history: a smash-up between the young Galaxy and a colossal companion 1. Unlike other objects in the main body of the Milky Way, which orbit in a relatively flat disk shape, these non-conformists were moving backwards, in orbits that were carrying them out of the Galactic plane. The team had spotted a set of 30,000 renegade stars. Working on fast-forward, unable to sleep from the excitement, Helmi and her colleagues sensed they were on to something. The University of Groningen astronomer and her team were racing to comb through the data for insights about the Galaxy before others got there first. Just days earlier, a flood of data had been released from Gaia, a European Space Agency (ESA) mission that has been mapping the Milky Way for five years. It had nothing to do with the weather - it was pure anticipation. Last April, Amina Helmi felt goose bumps while driving to work in the northern Netherlands.
0 kommentar(er)
