First images of star cluster from the Gaia Satellite

The Gaia Satellite has already sent its first images down to Earth approximately 40 days after its launch on the 19th of December. They show a dense collection of stars in the Large Magellanic Cloud at a distance of 170,000 light years.

“It’s fantastic and a huge relief to see that everything is going as it should with Gaia,” says the Danish astronomer Erik Høg, who has played a large role in the development of the European satellite, an astrometric satellite that measures the position, distance and movements of stars.

Erik Høg, associate professor emeritus at the Niels Bohr Institute, explains that the image shows a globular cluster of stars in the Large Magellanic Cloud, located at a distance of 170,000 light years from Earth. A globular cluster is dense collection of stars formed at the same time, that is, all of the stars are the same age. This globular cluster is very young, only 20 million years old, but globular clusters are often very old, between 4 and 14 billion years old.

Some globular clusters contain a billion stars, others only a few thousand. There are approximately 150 globular clusters in our Milky Way, but some large galaxies have many thousands of globular clusters. Globular clusters often contain some of the oldest stars in a galaxy and must have been formed almost at the same time as the galaxy, but it is still unclear what role they play in the development of a galaxy.

The recording is only has a 2.8 second exposure time and each star will be measured this way approximately 700 times over the next 5 years of the mission. From this, Gaia create a catalog with a billion stars. The position, movement and distance are given for each of them with great precision and this data will form the new astrometric basis for all branches of astronomy. 

“When Gaia really gets started with regular measurements, it will produce extremely large amounts of data. It will make precise measurements of the positions and movements of about 1 percent of the Milky Way’s approximately 100 billion stars. The goal is to create the most accurate picture of the Milky Way ever and to help to answer questions about the origin and development of the galaxy,” explains,” Erik Høg.

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