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We’ve seen a distant star from another galaxy far, far away, and the Milky Way is growing, thanks to baby stars born in the outer edge of our galaxy’s disk.

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[♪ INTRO].

When you look up on a clear night, virtually all of the stars you can see are part of the Milky Way. Even the farthest one you can find without a telescope is less than 20,000 light-years from you.

That might seem really far away, and yeah it is, but space is way bigger than our little neighborhood. It’s so huge that it’s hard to study the billions of stars outside the Milky Way. In fact, the farthest star we’ve isolated is in a galaxy only 55 million light-years away.

At least, that’s what used to be true. According to a paper published this week in Nature Astronomy, that record was blown out of the water. Now, the most distant single star we’ve ever seen is 14 billion light-years from us!

Yeah, billion. With a B. In general, it’s not that uncommon for astronomers to observe faraway objects.

For example, with telescopes, they can see the brightest supernovas up to 10 billion light-years away. But individual stars are normally impossible to make out even a hundred times closer than that. Unless they’re gravitationally lensed.

This is what happens when a large amount of mass, like a galaxy, or an entire cluster of galaxies, bends, distorts, and magnifies the light from objects behind them. It’s a phenomenon that happens because objects with a lot of mass actually distort the space around them. On average, galaxies experiencing gravitational lensing get magnified about 50 times their ‘normal’ brightness.

But this new star, which was found behind a galaxy cluster around six billion light-years away from here, got magnified 2000 times! That star’s name is officially MACS J1149 Lensed Star 1. But the team that found it unofficially calls it Icarus.

Thank you, astronomers! Scientists first found Icarus almost by accident, when they were studying images of a supernova the Hubble Space Telescope took in 2016 and ‘17. While studying the pictures, they noticed a second bright spot not too far away.

It was also varying in brightness over time, but not the way that supernovas do. Specifically, the colors of light coming from it didn’t change over the months of observation. Further analysis of those colors revealed the object was a blue supergiant.

These are stars much larger, more massive, hotter, and up to hundreds of thousands of times brighter than our Sun. You know, just in case you needed another reminder that space is pretty hardcore. All blue supergiants have similar profiles, so by comparing Icarus’s light against stars in our galaxy, the astronomers were able to calculate its distance.

They found that the light it’s emitting is 9 billion years old, and because the universe is expanding, that puts it about 14 billion light-years from us. But how did Icarus manage to be magnified 2000 times, when the regular amount from gravitational lensing is a measly 50? The answer is micro-lenses, small objects within the larger lens, like individual stars, that provide their own additional magnification.

Lenses within lenses. That boost is only temporary, because the micro-lenses will constantly be moving into and out of alignment. But if the timing’s right, the effect is massive.

Microlensing has even been used to find exoplanets outside the Milky Way! Icarus isn’t just a star for the record books, either. By studying the pattern by which it gets magnified over time, astronomers will be able to model exactly how matter is distributed in the lensing galaxy.

That includes its mysterious dark matter, which we can’t see but which has gravitational effects on other bodies. So besides smashing records, Icarus probably has a lot more to teach us. In other news announced this week, the Milky Way might be… getting bigger.

At least that’s what astronomers presented this week at the. European Week of Astronomy and Space Science in Liverpool. Our galaxy has been around for a while, and it’s grown as new stars formed over millions and billions of years.

Previous work has shown that stars of different ages now exist in different parts of the galaxy. For example, in the central bulge and galactic halo, there are lots of older stars, because there isn’t much raw material left there to make newer ones. Meanwhile, in the outer edge of our galaxy’s disk, studies have identified star-forming regions where baby stars form all the time.

And general models for galactic evolution suggest that the new stars in these regions will slowly cause the galaxy to grow. If you think about, it makes sense. It’s like a city growing because people keep building new neighborhoods on the outskirts of town.

Still, it’s hard to actually study this happening in the Milky Way, ‘cause we’re kinda stuck inside of it. To get around that, a team of astronomers studied two other galaxies that might have similar spiral structures to ours. If these galaxies seem to be getting bigger from star formation at their outer edge, then it’s not unreasonable to infer that the Milky Way is, too.

By collecting optical, ultraviolet, and infrared data of young, blue stars in these galaxies’ outer disks, scientists were able to calculate their vertical movement, how much they were moving up and down compared to the disk. Then, they could convert that into a galactic growth rate. These stars appeared to have velocities of about 500 meters per second, so the Milky Way could be growing at that same rate.

That seems pretty fast, but it’s really not too speedy on a galactic scale. In about 3 billion years, it means our neighborhood would only have grown by 5%. Then again, that growth rate might be completely messed up by then, because our galaxy will collide with Andromeda in about 4 billion years.

But hey, no matter what happens, studying how galaxies grow still helps us better understand the universe. Because even though the Milky Way is our home, there’s a whole lot we don’t totally understand about our corner of space. But that doesn’t mean that there’s not a ton to celebrate about our corner of space!

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