Thursday , September 16 2021

Our overview of the starry sky is much improved



The Gaia collaboration has recently released a new round of star measurements in the Milky Way. – It’s a treasure chest, astronomer Håkon Dahle told forskning.no.

The Gaia Observatory is a satellite and space telescope that looks at stars in the Milky Way. It measures mainly two things: where a star is and where it’s headed. It is operated by the European Space Agency (ESA).

And now there has been an update of these measurements, which can provide fertile ground for a great deal of different astronomical research.

The Gaia collaboration released recently updated measurements of approximately 1.8 billion different bright spots in the sky. Most of these bright spots are stars in our own galaxy. Gaia has collected detailed information on how about 1.4 billion of these bright spots move in the Milky Way itself.

– It’s a treasure chest, Håkon Dahle told forskning.no. He is an astronomer and researcher in the UiO Department of Theoretical Astrophysics.

These positions and speeds can reveal a great deal about our own galaxy.

The history of the galaxy – and the future

– It actually tells us the story of our own galaxy, says Dahle.

Once you know how all these stars are moving, you can also rewind time and track how the stars have moved throughout the galaxy.

– You can tell where stars are formed, and how they have spread throughout the galaxy.

This has already yielded many research results. Research based on measurements of Gaia, for example, has shown that the dwarf galaxy Sagittarius nearly collided with the Milky Way, and probably turbulent stars in the Milky Way hundreds of millions of years ago, according to ESA .

This also means that scientists can make more accurate simulations of the future of the galaxy. A research group has simulated the galaxy, which says something about how the stars in the Milky Way will move over the next 400,000 years.

This is how a simulation of well over a billion stars looks, and how they move in the galaxy in the next 400,000 years, observed by Gaia.

This is how a simulation of well over a billion stars looks, and how they move in the galaxy in the next 400,000 years, observed by Gaia.

Another research article based on the new data has provided an accurate measurement of how our own solar system moves around the galaxy center. This is due to the fact that the researchers received better reference points than before.

The updated dataset is the first part of a larger release to come 2022. As Gaia has been observing the stars for some time, it also means that precision is increasing. This is the third time these measurements have been updated, and the accuracy will be greater. You can see the various catalogs on the ESA pages.

This is how an artist imagines a Gaia telescope looks when looking at the starry sky.  Launched in 2013, the telescope rotates Lagrange's fixed point L2, about 1.5 million kilometers away from us.

This is how an artist imagines a Gaia telescope looks when looking at the starry sky. Launched in 2013, the telescope rotates the fixed point of Lagrange L2, about 1.5 million kilometers away from us.

Quasars or not?

These measurements can be used for a great deal of different research, and Dahle gives another example. Among other things, he investigates quasars – black holes that emit a lot of light and radiation.

The quasars are a long way from us, and do not exist in our own galaxy. The Milky Way is just over 105,000 light years wide, but the quasars can be ten billion light years away. These date from a much earlier period in the evolution of the universe.

They still shine so brightly that they can be seen as tiny points of light in the sky. If such a point does not move over time in Gaia’s measurements, it can mean that it is extremely far away.

This is the same effect you see from a train window, for example. The poles along the railway line move quickly past, but the mountain on the horizon is unlikely to move as you travel.

Thus, researchers can find new quasars by examining such sedentary dots of light, to see if, for example, they emit radiation that indicates they are quasi-quasars.


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