Astronomers have revealed the farthest reaches of our galaxy

Not only is trying to visualize the size of the universe a daunting task — and somewhat unsettling — but it’s also a paradoxical one. In a sense, our cosmic vastness is both Limited Because it hasn’t been around forever…and infinite because it’s constantly getting bigger in every direction. The most manageable thing, in terms of cosmic mapping, is to quantify all things inside Our universe seems to be.

And what better place to start than our own Milky Way? Astronomers announced this week, at the annual meeting of the American Astronomical Society in Seattle, that they may finally have it. identified the Milky Way’s outermost boundary.

In short, they estimate that our universe extends more than a million light-years from the galactic center, which lies about halfway to our neighboring galaxy, Andromeda.

Raja Guathakurta, professor of astronomy and astrophysics at the University of California, Santa Cruz and co-author of the study of the findings, said in statment. “Our galaxy and Andromeda are both very big, and there is no space between the two.”

For context, a light year is about 5.88 trillion miles (9.46 trillion kilometers) long and at 3,000 mph — close to the speeds of Orion spacecraft, Artemis I that circled the moon and back last year – it took you over a billion hours to cover that distance.

I don’t even want to write how long it will take to travel not just one, but a Million light years.

The clues were in the stars

Basically, you can think of the territory of the Milky Way divided into three sections.

First, there are the iconic spiral arms (one of which holds our solar system) wedged inside what’s known as a “thin disk,” which is pretty much a flat disk dotted with stars, planets, and moons about 100,000 light-years across.

Milky Way

This illustration shows what we think the Milky Way looks like, with two large spiral arms.

NASA/JPL-Caltech

The bulging central region of this disk is surrounded by an inner halo containing some of the oldest stars in our galaxy and extending hundreds of thousands of light-years in each direction.

Finally, there is the outer aura.

This elusive area, floating around his inner aura, he controlled dark matter (nervous music) It makes up most of the mass of our galaxy. However, it is “the hardest part to study because the outer limits are so far away,” GuhaThakurta said. “The stars are very sparse compared to the high stellar density of the disk and bulge.”

However, GuhaThakurta and his fellow researchers came up with an idea for how to tell where the Milky Way’s outer halo ends.

The three distinct parts of the Milky Way.

This illustration shows the inner and outer halos of the Milky Way. The halo is a spherical cloud of stars surrounding a galaxy.

NASA, ESA and A. Field (STScI)

They track what is known as RR Lyre stars living in its hazy glow. In short, RR Lyrae stars are special stellar objects of the type that pulsate in their brightness. They regularly expand and contract, appearing to astronomy instruments on Earth as glowing a little more powerfully, then fading gently — over and over again.

“The way it varies its brightness looks like an EKG — it’s like the heartbeat of a galaxy — so brightness goes up quickly and goes down slowly, and the cycle repeats perfectly with this very distinctive shape,” GuhaThakurta said. “In addition, if you measure their average brightness, it’s the same from star to star. This combination is great for studying galactic structure.”

In other words, RR Lyrae stars are better at measuring distance because it is possible to get average brightness on them. Other types of stars, for example, might be really bright because they’re close or because they’re…really bright. RR Lyrae’s stars are less questionable. Its brightness is easily related to its distance, so it helps scientists Calibration of the structure of the entire universe.

“Only astronomers know how painful it is to have reliable trackers at these distances,” Yuting Feng, a UCLA doctoral student and lead author of the study, said in a statement.

Feng and Guhakurta won the jackpot when they reallocated the data collected by Virgo Next Generation Cluster Survey, that photographed a large group of galaxies near the Milky Way. During its existence, this program also happened to capture a group of foreground stars in the same field – 208 of them were RR Lyrae stars.

“The data we used is kind of a by-product of this survey,” Feng explained. “This powerful sample of distant RR Lyrae stars gives us a very powerful tool for studying the halo and testing our current models of the size and mass of our galaxy.”

In addition, according to Feng, the team’s observations confirmed ancient theoretical estimates of the corona’s outer limits.

Those estimates suggest the halo lies roughly 300 kiloparsecs, or 1 million light-years, from the galactic center — and the team’s study found that RR Lyrae stars live at distances from 20 to 320 kiloparsecs, their last term just over A million light-years away from the center of the galaxy.

This is pretty darn close.

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