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Right now, humanity is preparing a bunch of fireworks to ring in the new year.
But the rest of the universe is also always up for some explosions.
And this week in Nature Astronomy, a team of scientists may have found
the leftovers of one mysterious cosmic explosion, nicknamed “the Cow.”
This phenomenon is officially called AT2018cow,
and it started in June of 2018 as a flash of light around 200 million light-years away.
A lot of these events are signs of a supernova,
which are caused by exploding stars.
But three days after /this/ light showed up,
it had grown to be ten times brighter than your standard supernova.
Then, it faded in the following months.
Based on the kind of light it emitted, and the rate at which its brightness changed,
the explosion was classified as an FBOT: a fast blue optical transient.
Most FBOTs have been associated with
extreme supernovas caused by massive stars collapsing.
But with how bright it got, and how fast its brightness increased,
Cow’s light signature is even more extreme.
It was the brightest FBOT ever detected.
So astronomers got excited and they rushed to explain what created it.
One team hypothesized that the explosion
was caused by a black hole tearing apart a star.
Another proposed it was just a supernova, and that the extra light
came from a remnant neutron star or a black hole shining through the debris.
But if that’s the case, then scientists need to figure out
if there’s actually a remnant out there.
And that’s where this new research comes in.
This team used the NICER instrument aboard
the International Space Station to look at the Cow’s X-ray emissions.
They detected a steady signal at one frequency of X-ray light,
hinting at a rapidly rotating, compact object, like a neutron star or black hole!
But which one it is isn’t clear.
The data don’t perfectly match either scenario.
It’s also unclear how this compact object was made.
Like, if the Cow was a supernova, this object could just be a remnant.
But the Cow could also have been a flare made by
material from a failed supernova falling back into a compact core.
Either way, this team thinks this all has something to do with a dying star.
And if further research shows the Cow actually was a supernova
creating its remnant, this will be the very first time
astronomers were able to watch this process happen in real time!
Moving from extreme explosions to extreme planets…
Last week in the journal Nature, astronomers revealed a record-breaking exoplanet;
record-breaking not because of the planet itself, but because of the stars it orbits.
Until recently, the most massive star with a known exoplanet
was about three times the mass of the Sun.
Now, there might be some selection bias here:
It’s harder to pick out the passing shadow or gravitational pull of a tiny planet
compared to a massive star, especially since massive stars are also brighter.
Still, these stars also pump out a ton of high energy radiation.
And that could vaporize and push away
any matter that might try to come together to make a planet.
So, stars over three solar masses might be
a lot less likely to have planets around them.
But even if it is unlikely, this new study shows that it is not impossible.
In 2019, images from the Very Large Telescope in Chile revealed
a planet around 325 light-years away orbiting the binary star system b Centauri.
And in this new paper, a team did follow up observations
to prove that it is definitely there and isn’t just a background star.
Like, with most exoplanets, we only know they’re there through
indirect measurements of their stars’ light.
But we have actual photographic evidence of this planet.
It’s called b Centauri b!
And that’s especially cool because of how massive these stars are.
They have a collective mass somewhere between six and ten times that of our Sun,
more than any star or star system we have seen with exoplanets.
And the planet itself isn’t too shabby, either:
Based on the amount of light it emitted, the team estimated it’s about
11 times the mass of Jupiter, making it among
the most massive exoplanets we have ever seen.
But astronomers are not sure how it formed.
Most planets begin in a large disk of material, when individual grains of stuff
start sticking to each other and then, the whole thing grows from there.
If that’s what happened here, maybe b Centauri b formed closer to its stars
where all the rocky material was, and then gravitational interactions
flung it into its current orbit.
Alternatively, this planet may have formed the way stars do.
Basically, it might have been far enough from its stars that
the disk of material was relatively cold and slow-moving.
And under those conditions, a large clump of the disk could have
collapsed under its own gravity to make a planet.
In the future, hopefully we will get more definitive answers
with the next generation of telescopes.
For instance, the Very Large Telescope will soon be joined by
a larger sibling…their calling it the Extremely Large Telescope.
With better eyes, astronomers will be able to investigate just how rare exoplanets
are around stars this big, and possibly
update the textbooks on planetary formation, as well.
In addition to very large telescopes here on Earth,
we also have some eyes in the sky like those of Hubble!
To keep those eyes up and going scientists resorted to servicing missions,
the main reason why the Hubble was able to work
for more than 30 years of service in the skies above Earth.
To keep that great scientific legacy going,
we have immortalized it as December’s pin of the month.
Plus it’s also very cute, I mean look at the lil’ astronauts on it.
So, if you’d like to snatch one, they will only be available in the month of
December, and then next year, we’re gonna kick it off with a whole new pin!
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