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[♪ INTRO]
In a universe full of remarkable objects,
few things stand out more than neutron stars.
They’re basically physics stretched to its breaking point,
and these weird worlds have fascinated astronomers for decades.
But at least one thing on neutron stars isn’t so extreme: their mountains.
In fact, according to new computer simulations presented this week at a meeting of
the Royal Astronomical Society, you wouldn’t even be able to stub your toe on one.
And that could make the job of detecting
these strange objects surprisingly challenging.
Neutron stars are the leftover cores of dying stars large enough to
explode in powerful supernovas, but too small to create a black hole.
As the name suggests, they are made almost entirely of neutrons, the result of the
dying star’s protons and electrons merging under the violence of the explosion.
And that gives these objects incredible density.
They are between 10 and 20 kilometers across,
but a teaspoon of neutron star material would weigh around 1 trillion kilograms.
All that mass leads to an enormous gravitational pull,
which evens out a neutron star’s bumps and makes it a virtually perfect sphere.
But nothing in nature is ever perfect,
so astronomers have long wondered how big the surface deviations might get.
Or, as we might say here on Earth, how big are the mountains?
Past analyses have suggested that these “mountains” probably couldn’t grow to
more than a few centimeters before the neutron star’s surface
would buckle and redistribute the material.
But in a new, more nuanced simulation described this week,
physicists calculate that their true height could be even smaller,
possibly only a fraction of a millimeter.
Whether or not these still deserve to be called mountains is debatable,
but whatever you call these bumps, their size
may actually have some practical implications.
Since neutron stars are so small and dark, they’re hard to spot in the sky.
So astronomers are interested in searching for neutron stars
by looking for the gravitational waves they emit.
According to Einstein’s theory of general relativity,
any rotating object whose gravitational field is not
perfectly symmetrical will create faint ripples in the fabric of space.
So, using modern gravitational wave observatories like LIGO and VIRGO,
astronomers could potentially detect the presence of a neutron star,
even if they couldn’t see its light.
But those signals get fainter and fainter
the closer an object is to being a perfect sphere.
And a sub-millimeter-sized deviation on a
ten-kilometer-wide object is pretty close to perfect.
So, astronomers have their work cut out for them
if they hope to spot a neutron star using gravitational waves any time soon!
This week, we’ve also got the next chapter
in the ongoing saga of phosphine in the atmosphere of Venus.
To catch you up, last fall, a team of researchers published data suggesting
there were molecules of phosphine gas high in the planet’s atmosphere.
Which was a big deal, because the presence of that gas could be
an indicator not just of past life, but of life right now on our sister planet.
Then, in February of this year, another group pointed out some flaws in that study.
They argued that, at best, it suggests
the presence of a very little bit of phosphine, or maybe none at all.
Now, a new study sidesteps the question of whether the phosphine actually exists
to examine where it could come from if it did.
And that would help planetary scientists figure out
how reasonable it is to even consider that life was involved.
The paper, published Tuesday in the Proceedings of the National Academy of
Sciences, points the finger at explosive volcanic activity on Venus’ surface.
Now, this isn’t the first time that volcanism has been considered.
But past studies have argued that the number of eruptions it would take to account
for the estimated amount of phosphine on Venus is just unrealistically high.
This time, though, the authors of the new work argue for a more nuanced picture.
Previous research supposed that active volcanoes would deliver the
phosphine-producing mineral phosphorus directly into the atmosphere,
where it would react with sulfuric acid to form phosphine.
But in this study, the authors imagine that the phosphorus-containing minerals
are first delivered to the surface through volcanic lava flows.
Then, at a later time, the volcano undergoes an episode of explosive volcanism,
in other words, it blows its top off thanks to a build-up of pressure.
This explosion converts the minerals into dust,
and carries them high into Venus’s atmosphere.
There, finally, they react with sulfuric acid in the planet’s atmosphere
to create the phosphine gas that may have been observed.
If volcanoes are really responsible for Venus’s supposed phosphine,
these explosive eruptions would have to be big to launch
the phosphine-producing minerals high enough into the atmosphere.
The authors calculate that the eruptions would need to be
at least similar in scale to the explosion of Krakatau here on Earth in 1883.
Measurements suggest that that eruption had the energy of
around 200 million tons of TNT, and it affected the climate of the entire planet.
This isn’t the first time research has suggested that enormous eruptions
once happened on Venus, so it’s not unthinkable.
Or, again, maybe the phosphine gas doesn’t exist at all,
and this is an explanation of something that isn’t even happening.
And that is how science works: Ideas are put forth, improved, altered, or even
dismissed until one gains enough support to be accepted as scientific theory.
But more data would be very helpful here,
and to that end, there is some good news.
NASA and the European Space Agency have recently announced not one, not two,
but three new missions to Venus to launch in the next decade.
They will provide a better understanding of
the planet’s atmosphere, surface, and interior.
As long as they can dodge any giant exploding mountains that might exist!
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[♪ OUTRO]