A treasure trove of data is about to reply some big questions on our galaxy.
The data, compiled by the European Space Agency’s Gaia mission, accommodates an unprecedented quantity of details about greater than 1 billion of the brightest objects in the sky. Astronomers hope the new data, which will likely be launched June 13, will assist solve some main mysteries about the beginning and lifetime of the Milky Way and the stars in it.
The Gaia mission launched in 2013 and is thought for creating the most detailed map of the Milky Way by charting the exact positions, distances and velocities of practically 2 billion stars. The upcoming data set will add a brand new dimension: It will reveal the chemical compositions of tens of thousands and thousands of stars, permitting astronomers to reply essential questions.
Hovering round Lagrange Point 2 (not too removed from one other groundbreaking mission, the James Webb Space Telescope), Gaia scans the total sky about each two months. The 2 billion celestial objects the telescope sees make up solely about 1% of the complete stars in the Milky Way. But with the assist of subtle laptop algorithms and plenty of scientific information, astronomers can extrapolate these measurements to study the galaxy as an entire.
Here are a few of the most fascinating mysteries the Milky Way explorers are desirous to crack with the new data.
Related: How many stars are in the Milky Way?
1. Where do stars come from?
By measuring the exact positions, distances and velocities of huge portions of stars, Gaia does rather more than map the Milky Way as it’s at the moment. Because objects in the universe comply with the guidelines of physics, astronomers can mannequin the previous trajectories of these stars and basically play the film of the Milky Way thousands and thousands, and even billions, of years. But that was already attainable with the beforehand launched data. With the new data set, astronomers will be capable of search for extra.
For the first time, the Gaia mission crew will launch what they name “astrophysical parameters” for half a billion stars. These parameters, derived from the gentle spectra of the stars measured by Gaia (that are basically the fingerprints of how these stars soak up gentle), reveal details about the chemical composition, mass, age, temperature and brightness of every of the measured stars. And that may be a big deal, Gaia venture scientist Jos de Bruijne informed Space.com.
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“You will really get to know the stars,” De Bruijne stated. “They basically tell you who they are. It’s like having an anonymous group of 500 million people and now you get to know every single one of them — their names, how old they are, where they came from.”
For 30 million of those stars, Gaia measured the chemical composition of stellar atmospheres, which is an identical to the chemical composition of the molecular clouds that these stars have been born in billions of years in the past, De Bruijne stated. By combining the details about chemical composition with the modeling of the stellar trajectories, astronomers will be capable of monitor teams of stars to their birthplaces inside (but additionally outdoors) the Milky Way.
“It’s really unique that we now can do this with such a high number of stars,” De Bruijne stated. “That’s something that is otherwise really difficult and expensive to do with ground-based telescopes, as it takes a lot of time.”
2. How does the galaxy “hang” collectively?
Although Gaia has been scanning the Milky Way since 2014, there may be nonetheless lots astronomers do not perceive about the galaxy. Studying our galactic dwelling shouldn’t be a straightforward activity. Because we’re inside the galaxy, we can’t “see the forest for the trees.” It is unattainable even for Gaia to look by the thick mud and gasoline clouds obscuring the Milky Way’s heart (the place the just lately photographed supermassive black gap Sagittarius A* lurks) to the different aspect of the galactic disk.
But by the gradual enhancements in Gaia data — and with the assist of different commentary strategies, comparable to radio astronomy — the big image is coming collectively, piece by piece. That means we’re getting nearer to fixing a few of the nice puzzles, together with the distribution of darkish matter in the galaxy.
“All the stuff in the galaxy is exerting gravity at every star, and this gravity determines how fast the star moves,” De Bruijne stated. “So by measuring motions of stars, you also probe the matter distribution in the Milky Way. And that is really important for figuring out how the galaxy hangs together.”
One of the lingering uncertainties associated to the distribution of stars in the Milky Way is the galaxy’s trademark spiral construction. Astronomers principally agree that the Milky Way has 4 spiral arms, the dense twisting streams of stars and gasoline that seem to emanate from the galaxy’s heart. But there are fairly just a few factors of competition round these spiral arms: Astronomers nonetheless debate the dimension and prominence of the particular person arms, in addition to their actual place in the Milky Way’s disk. The new data would possibly assist reveal the spiral construction with higher readability.
“With the astrophysical parameters that we now have, we can directly create samples of stars for specific science cases,” De Bruijne stated. “We know that the spiral arms are mostly made of young stars. It’s where stars form. So, with the new data, we can look, for instance, at stars that are no older than 100 million years.” (In stellar phrases, 100 million years is infancy. For comparability, our solar is 4.6 billion-year-old and can die in 5 billion years.)
Again, Gaia does not solely see the spiral arms as they’re at the moment; it permits astronomers to mannequin the arms’ evolution into the previous and the future.
With the new data, astronomers will be capable of look farther away from the solar, thus instantly sampling a bigger portion of the galaxy’s spiral arms, Anthony Brown, an astronomer at Leiden University in the Netherlands and chair of the Gaia Data Processing and Analysis Consortium, informed Space.com. Still, understanding the galaxy as an entire will stay a problem.
3. What occurred in the Milky Way’s “childhood”?
Gaia measurements allow astronomers to carry out what they name “galactic archaeology.” By reconstructing the trajectories of thousands and thousands of stars, they will study occasions that occurred in the distant previous, billions of years in the past. These occasions contain cataclysmic collisions with different galaxies, the ripples of which may be noticed in the galaxy to this present day.
One of the most well-known discoveries that got here out of the earlier Gaia data releases was the collision with a smaller galaxy known as Gaia Enceladus, which occurred 8 billion to 11 billion years in the past. At that point, the Milky Way was a lot smaller than it’s at the moment, and when it devoured the smaller intruder, it skilled appreciable upheaval. Brown stated the collision with Gaia Enceladus was “the last significant merger that the Milky Way underwent” in its violent childhood. He hopes that with the new data set, astronomers will be capable of look additional again into the galaxy’s historical past and hint a few of the even earlier collisions.
“We have already seen some authors trying to look more than 10 billion years into the past at the first hints of the Milky Way’s formation, some 12 [billion] or 13 billion years ago,” Brown stated. “With the new release, we should be able to do this much better, thanks to the astrophysical information that we will be releasing. Now that we know the ages and the chemical compositions of stars, we can figure out the time order in which events happened, and we can also see where stars originally came from.”
The Milky Way continues to eat up smaller galaxies to this present day. The two dwarf galaxies often known as the Large Magellanic Cloud and the Small Magellanic Cloud, which orbit round the outskirts of the Milky Way, will at some point be fully swallowed up by the Milky Way, fashions present. The remnants of different dwarf galaxies may be traced in the Gaia data in the type of stellar streams scattered over the Milky Way’s halo, Brown stated.
Just because it emerged from violent collisions, the Milky Way will at some point die a violent dying. About 4.5 billion years from now, the Milky Way will collide with its nearest massive galactic neighbor, the Andromeda galaxy. This collision is anticipated to occur at about the similar time as the dying of the solar, so humankind is unlikely to be round to see it. The new Gaia data launch may, actually, shed some gentle on this cataclysmic occasion, Brown stated.
4. What’s improper with the Milky Way’s disk?
Gaia’s earlier data revealed that the Milky Way’s disk is warped, moderately than flat. It additionally wobbles like a spinning prime because it rotates round the heart of the galaxy. Astronomers assume this wobble resulted from a not-so-distant galactic crash.
Brown hopes the new data will shed extra gentle on this disturbance and its origins. The upcoming data launch will include details about the movement of greater than 30 million stars in Gaia’s line of sight — that’s, how briskly they transfer towards or away from the telescope, or the so-called radial velocity. The prior releases contained radial velocities of solely 7 million stars. The extra data astronomers have, the finer the particulars their evaluation instruments can reveal about the galaxy.
“We can try to measure [the disturbance] in different locations in the galaxy or look at how it affects certain types of stars,” Brown stated. “And this tells us a lot about what, exactly, caused the disturbance of the Milky Way’s disk. This is the kind of thing you can start doing with this much more expanded data sample.”
And extra is but to return
Gaia is presently the scientific mission that generates the most scientific papers, and in keeping with De Bruijne, the greatest continues to be to return. The June 13 data dump will even include the largest-ever set of details about binary star techniques in the Milky Way, and De Bruijne expects that data to spawn groundbreaking discoveries.
In addition, Gaia has assembled the largest database of chemical compositions of asteroids in the photo voltaic system. The consortium processing Gaia’s measurements is growing more and more higher algorithms that allow scientists to study extra about the stars Gaia sees. The mission will proceed scanning the sky till 2025, when it is going to run out of gasoline. Two extra big data releases are anticipated to comply with the one on June 13, and they’ll carry new surprises, together with hundreds of newly found exoplanets, De Bruijne stated.
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