Have you ever wished you could jam with the cantina band in Mos Eisley, or watch a double
sunset from a moisture farm?
Well, you might be in luck, because in a study published this week in the journal Nature
Astronomy, a group of researchers announced that they’ve spotted debris that might have
come from a rocky planet that’s part of a binary star system — a system with two
stars instead of one.
In other words: we’ve found signs of a Tatooine-like planet.
I’m Stefan Chin, filling in today to bring you SciShow Space News.
Now, we’ve found a planet in a binary star system before.
Astronomers discovered the first one back in 2011, and since then they’ve found a
few others.
But even though those discoveries led to plenty of headlines saying we’d found Tatooine,
you wouldn’t want to start a moisture farm on any of those other planets because they’re
all gas giants.
It was still exciting though, because hey, planets with two suns!
Plus, in binary systems, the gravitational pull from both stars can make it hard for
rocks to clump together to form rocky planets.
So astronomers thought that a real Tatooine – or a slightly more similar one, anyway
– might not even be possible.
Until now.
Using two telescopes in Chile – the Gemini Observatory South telescope and the Very Large
Telescope – the researchers found evidence of shattered asteroids around a star system
far, far away called SDSS 1557.
At first, the astronomers thought they were just looking at a single white dwarf: a small,
very dense star, about 1000 light years away.
But then they realized there was also a brown dwarf, a smaller, sort of “failed star”
that’s too small to begin fusing hydrogen and helium.
The brown dwarf was hiding among the dust and debris around the white dwarf.
The white dwarf’s gravitational pull is strong enough to drag in some of the debris
around it, which changes the wavelengths of light the star emits.
Using special instruments on the telescopes, the team was able to track and analyze those
wavelengths, which can say a lot about what’s in the debris.
So far, the stuff we’ve found flying around in binary systems has been mostly made of
ice and carbon.
But it looks like these asteroids are rich in elements like silicon and magnesium, which
also make up rocky planets like Earth and Mars.
Based on the amount of debris they measured falling into the white dwarf star, they think
the asteroid it originally came from was at least four kilometers wide.
If it’s possible for such a large, rocky asteroid to form, that means many large asteroids
could have come together and formed a rocky planet, too!
The astronomers plan to use the Hubble Space Telescope to take a closer look next year.
No word yet if the astronomers also saw what looks like a strange, small moon among the
debris, but we’re not complaining about that one.
But even if it were real, the Death Star still probably wouldn’t be the most dangerous
thing in the universe.
Because according to another study out this week in Nature Astronomy, supermassive black
holes are apparently ripping apart stars way more often than we used to think.
Like, 100 times more often.
Astronomers used to believe it was pretty rare for a black hole to swallow a star, which
is called a Tidal Disruption Event, or TDE.
We’d only ever seen these acts of stellar cannibalism happen a few times in huge studies
with thousands of galaxies, so we thought TDEs only happened once every 10,000 to 100,000
years per galaxy.
But it looks like we may have underestimated black hole appetites.
In the new study, astronomers surveyed just 15 galaxies over 10 years, and even in this
tiny sample, they spotted a star giving off a huge flare of light – which is kind of
like a star’s SOS signal as it’s been ripped apart.
Other objects, like supernovas, can give off bursts of light, too – but this flare’s
wavelengths and other properties were different than any supernova we’ve seen before.
Instead, it looked like what we would expect to see from a TDE, which might suggest that
TDEs aren’t really that rare.
We were just looking in the wrong place.
See, for this study, the team focused on galaxies that were colliding with one another.
Every large galaxy has a supermassive black hole in the middle, so when galaxies come
together, a lot of new stars are formed, but those stars are also being formed right between
two huge black holes.
Lunch time!
All this violence isn’t really something we need to worry about in our own galaxy for
the moment, but in 5 billion years, when the Milky Way crashes into the Andromeda galaxy,
astronomers think TDEs will become much more frequent.
Instead of seeing a star get swallowed up every 10,000 to 100,000 years, we’ll probably
see it happen once every 10 to 100 years.
And if humans manage to stick around to see it, well, good job humanity!
You’re in for quite the show.
Black hole-gobbled stars that close to home would flash brighter than anything else in
the night sky, so no telescope needed!
Thanks for joining me for this episode of SciShow Space News, and thanks especially
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