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Astronomers have discovered some pretty extreme,
record breaking stuff as they’ve explored the universe.
Each new discovery could be
the next new biggest, oldest, or fastest, and so on.
So as we wrap up 2022, let’s celebrate a few of the cosmic “winners” discovered this year…
at least while they still hold their titles!
First up is the oldest known planetary nebula,
which astronomers found in a group of gravitationally bound stars
known as the open cluster M37.
Despite their name, planetary nebulas don’t have anything to do with planets.
They are actually big bubbles of gas leftover from when a star like our Sun dies.
But when seen through a small telescope
they kind of look like a planet does through the same telescope.
They both look like smudges.
When the star runs out of fuel, its outer layers of gas are shed into interstellar space,
and the core collapses into a hot, dense ball called a white dwarf.
As it cools down, the white dwarf emits a ton of light,
which interacts with all that gas producing some very lovely pictures.
By studying that light, scientists can also calculate a planetary nebula’s kinematic age…
basically, how old they think it should be
based on how fast the gas is speeding away from its white dwarf.
Most of the time, these nebulas only last for 5,000 to
25,000 years before the gasses become too spread out to see.
But this nebula appears to be a whopping 70,000 years old!
And it’s also special in another, not quite record breaking way.
Out of the 4,000-odd planetary nebulas that astronomers have cataloged in the Milky Way,
this is only the third that’s been found in an open cluster.
Since stars in a cluster all tend to form at the same time from the same big clump of gas,
this gives astronomers a kind of space-based laboratory.
They can study this nebula’s relationship with its sibling stars
to learn more about the star that died, and to better predict what any particular star
will look like as a white dwarf and planetary nebula in the future.
Maybe we’ll apply that knowledge to the Sun one day,
and get some pretty models
of what our planetary nebula could be, long after we’re gone.
Speaking of white dwarfs, our next record goes to a white dwarf and its stellar partner
for having the fastest orbital period for this type of dynamic duo.
They circle each other once every 51 minutes.
Unlike our Sun, many stars live out their lives with a companion.
Sometimes the two stars have similar masses, but sometimes they’re really different.
And when they’re different, the star that’s more massive will run through its life
cycle more quickly, because it shines brighter and uses up its fuel faster.
That’s what happened for our record-setters.
The white dwarf has a mass which is roughly half that of our Sun,
but that means the star it came from was more massive than that.
Meanwhile, the star it’s co-orbiting is tiny. It’s only about a tenth the mass of the Sun.
And they’re orbiting each other this fast because they’re super close together.
Basically, you’ve got a star and a stellar remnant in an orbit smaller than our Sun is!
Scientists were able to determine these masses, as well as that 51-minute orbit,
by studying the change in brightness as they eclipsed each other from Earth’s perspective.
But that light also showed these stars are special in another way.
The white dwarf is stealing the hydrogen gas off of its stellar buddy.
Binaries that do this have a special name: Cataclysmic Variables.
Astronomers have been hunting for a system
where the white dwarf has transitioned out of stealing hydrogen,
because it’s already got all of it, and starts stealing helium.
Computer models predict this white dwarf is very nearly there…
at least on astronomical time scales.
The transition is scheduled to happen in 75 million years or so,
and all the while the two objects are expected to continue spiraling in towards each other.
When the white dwarf starts stealing helium,
they’ll be so close that their orbit will only be 18 minutes long!
But they aren’t doomed to crash into one another.
Because of all this mass transfer, the white dwarf will grow and the star will balloon out,
pushing them apart until they settle into an orbit about half an hour long.
But that’ll take another 300 million years,
so you might want to make yourself a snack before settling in to watch that near miss.
Finally, we jump from the Milky Way to a galaxy far, far away.
Back in March, astronomers announced the discovery of a star nicknamed Earendel…
the most distant individual star ever detected.
The light we’re seeing now has spent 12.9 billion years
traveling across the universe to reach us.
But because the space between galaxies has also been expanding this whole time,
it’s way more than 12.9 billion light years away.
Normally, you wouldn’t be able to separate out the light of one star from its galaxy.
But in Earendel’s case, a unique alignment of cosmic features fell into place.
The star is part of a galaxy known as the Sunrise Arc,
which gets its name from its funky shape.
But the galaxy only looks that way because of an effect
called gravitational lensing.
Astronomers are trying to look at the Sunrise Arc through a galaxy cluster
whose mass distorts spacetime and bends the light traveling through and around it.
This happens in tons of space images.
Objects get duplicated, distorted, and also magnified.
And that magnification is what happened to Earendel’s light,
making it look brighter than it would normally appear.
While Earendel is the most distant star ever detected, it’s not the oldest.
It’s true that the farther away we look,
the further back in time we are looking.
But that doesn’t necessarily mean that the object emitting
the light we are looking at still exists.
Researchers estimate that Earendel would have been around 50 times the mass of our Sun,
which would make it a very hot and short lived star.
It would have exploded as a supernova after ten or so million years…
many billions of years before our solar system even formed.
Even though Earendel doesn’t actually exist anymore,
scientists can still study its light to learn a
bout what the universe was like 12.9 billion years ago.
But first, we need to actually confirm it’s a star,
and not some other source of light.
That’ll be a job for the James Webb Space Telescope,
when it manages to find the time.
These record breakers may soon find themselves dethroned,
as humanity keeps pushing the boundaries
of what we can detect across the universe.
But each step we take builds on what came before.
So stay tuned for 2023
Whatever extreme discoveries astronomers make
you can be sure the SciShow Space team is eager to cover as many as we can.
So if you want to keep up with the latest record holders,
make sure you’re subscribed.
Thanks for watching!
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