Four mysteries she can solve on 13/6

Next Monday (13), a number of new data from the European Space Agency’s (ESA) Gaia mission will be released, thus providing more detailed information on the chemical composition of tens of thousands of stars in the Milky Way. According to most of the astronomical community, this new data is expected to help us answer some questions about our “neighborhood,” which is still shrouded in mystery.

The Gaia mission was launched in 2013 and quickly became famous for creating the most detailed star map of the Milky Way. It contains extremely accurate information on factors such as position, speed and distance of almost 2 billion stars – if we know today how to use stargazing at great depth, we must at least be part of the ESA mission.

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This image shows the moment when the spacecraft from the Gaia mission successfully photographed the James Webb Space Telescope (Image: ESA / Handout)

However, like most major missions, Gaia mission information is published in datasets (or ” datasets”) – each series deals with a different theme. And the next press release from the European Agency coordinating the mission is the most anticipated so far, because …

… Gaia can tell us how the Milky Way stays “in place”

Observing the Milky Way is not as easy as it seems: one would think that because we live there, we should know everything about our “space district”. In fact, that’s exactly why we know so little. There is an expression – “to see the forest among the trees” – which emphasizes exactly how impossible it is for you to have the whole detail in an area if you are in the same area.

With the Gaia mission, this is also true to some extent, but advances in astronomical observation techniques and data collection and interpretation will allow us to advance our knowledge of the Milky Way to levels not yet known. . For example, it is possible that the next set of mission data will show us the distribution of matter – normal and dark – in our galaxy.

“Everything in the galaxy exerts gravity relative to each star, and it’s gravity that determines how fast a star moves,” Gaia project researcher Jos de Bruijne told Space.com. “By measuring the motions of stars, you can also examine the distribution of matter in the Milky Way. And that is very important to help us understand how the galaxy ‘stays in place’.

A practical example: the scientific consensus says that the Milky Way has a spiral shape with four arms extending from the center of the galaxy outwards, giving an idea of ​​circular motion. But we still do not know much about the size of each arm, their exact positions or information about their chemical composition. The Gaia mission can give us more intelligence on these points.

… this may also explain the “deformation” of the Milky Way disk

Early data sets from the Gaia mission have revealed that the central disk of our galaxy is not a flat, straight object, but a structure with multiple deformations. Its rotation is also not uniform, much more like a spinning top as it loses movement and begins to move “half twisted”, but still in the same place. According to some scientists, this may be the result of an influence of very, very old galactic proportions.

The forthcoming Gaia dataset contains information about the motions of more than 30 million stars trapped within the line of sight of the spacecraft that gives the mission its name – essentially radial velocity (how fast a star moves approaching or moving away from a telescope).

Now this information in itself is nothing new – previous datasets spoke the same for another seven million stars – but the amount by which this information is updated with more and more stars, gives a more general picture of the different regions of the Milky Way and, with a little luck we can deduce disturbances in the motion of stars closer to the center, which probably divide the deformations of the central disk.

Supernova Gaia14aaa, captured by spacecraft from the Gaia mission in 2014
The supernova Gaia14aaa, recorded by the spacecraft from the Gaia mission in 2014 (Image: ESA / Handout)

… With Gaia we can know where the stars come from

Okay, technically we know where stars are born: basically, those areas are full of gas and cosmic dust that facilitate the birth of new stars in a process that takes thousands of years – the so-called “star elementary schools”.

However, the Gaia mission can give us what astronomers call “astrophysical parameters” that measure different information from younger and older stars and would in practice be like recording a movie of the Milky Way, from its birth to these days. It’s true that the previous dataset already allowed us to do this to some degree, but the new data release promises such details for around 500 million stars.

“It’s like having a group of half a billion anonymous people, and now you can find out everything about each one of them – their names, their age, where they come from, etc.,” said de Bruijne.

Basically, the Gaia mission analyzed the chemical composition of these stars. Star formations are important information because they act as a “fingerprint” that goes back to the places where they were born – and some of these stars are billions of years old and do not necessarily originate here, but outside the Road.

In practice, this means that we can trace the history of these stars and hopefully identify not only which ones originated in our region in space, but also which ones came from outside and who knows what brought them here.

… Gaïa will tell us about the “childhood” of the Milky Way.

It may seem obvious, but the Milky Way was not always the Milky Way. Of course, it has always had that name because astronomers needed a name to work on their observations. But at some point before 8 to 11 billion years ago, our “space district” was much smaller.

During this period, an earlier set of data from the Gaia mission revealed a galactic impact with a smaller galaxy called “Gaia Enceladus”. We ended up devouring and incorporating the little striker, but not without changing our own composition: it was the “last significant fusion that the Milky Way experienced in a rather violent childhood,” said Anthony Brown, an astronomer at the University of Leiden.

Today we know that the Milky Way absorbed smaller galaxies during its (estimated) 13.6 billion life years. Astronomers have already tried to observe catastrophic situations – such as the collision of galaxies – in the Milky Way until well over 10 billion years ago, but there are not many traces of these events, at least not in the way we can measure from Earth.

However, the Gaia mission can give us much more detail about the history of the Milky Way stars, and this is an important detail: you can see that by the chemical composition, age and orbit of millions of stars, we can achieve the ability to deduce the timeline that things happened after, thus tracing a history of past events that will shed more light on this topic.

But it is not only the past that the Gaia mission data will live on: Just as they have absorbed smaller galaxies to date (the large cloud and the small Magellanic clouds are being devoured by us right now), the Milky Way will also suffer. a very good violent death: In about five billion years – the same period as the death of the Sun – the Milky Way would collide with Andromeda, our immediate neighbor in space.

We humans will hardly be around to see it happen, but the next dataset from the Gaia mission might give us more information and help us deduce more details on how it can evolve.

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