WASP 76b: Hot Jupiter Exoplanet that Rains Iron at Night

WASP 76b: Hot Jupiter Exoplanet that Rains Iron at Night


Hello Space Fans and welcome to another edition
of Space Fan News. In this episode astronomers at the European
Southern Observatory have observed an exoplanet that is tidally locked around it’s star
and because of this has extreme temperatures on the daytime and nighttime side. The temperatures are so hot that on the day
side, iron is a gas and at night that gas condenses into molten iron rain. It seems the more we look for and at exoplanets,
the stranger some of them become. We tend to be really focused on the Earth-like
ones because we like to fantasize that somehow, someday we could live on one of those. But Earth-like planets are elusive compared
to all the others that are out there and this week, astronomers using ESO’s Very large
Telescope and associated instruments have found a really strange exoplanet. The planet is called WASP-76b and it orbits
its star WASP-76 once every 1.81 days. That’s its year folks! The system is located some 640 light years
away in the areas of the sky bounded by the constellation Pisces. WASP-76b itself is what astronomers call a
hot-jupiter, meaning its about the size of jupiter and, well, it’s hot. It’s about1.8 times larger in radius than
Jupiter and is a little less massive (about .9 times the mass of Jupiter). Now a really large planet the size of Jupiter
going around it star once every couple of days is strange enough but because it’s
year is so short, that also means it’s pretty close to the star, which makes it very hot. Being so close also grabs it pretty strongly
to the star. WASP-76 is an F7 star that is about 1.7 times
bigger than our sun and 1.5 times as massive and because of all these factors, WASP-76b
is tidally locked to the star in its orbit around it. Tidally-locked means that the rate at which
the planet rotates matches its orbit around the star making one side of the planet always
facing the star and the other side facing away. So here we have a planet that’s way bigger
and more massive than Jupiter, going around an F7 star – which are known to, among other
things, emit large amounts of UV radiation – going around that star every couple of day
AND it has one side always facing the star and the other facing away… Well that’s a party where you know weird
stuff’s gonna happen. Astronomers looking at this system using ESO’s
VLT and specifically the spectral imager known as ESPRESSO, a fiber optics high resolution
spectrograph, and when they looked at the planet at various spots in the transit (that’s
the part where the planet passes between us and the star), on the day side of the planet
where temperatures were around 2400K, which means the daytime side of this star is comparable
to some of the cooler stars out there. Looking at the spectral images, they were
able to closely follow the neutral iron in the atmosphere as the daytime on the planet
progressed. Because different parts of the planet were
visible to us as the planet went around and correcting for all the motions of the planet
rotation and orbital motion, the team look at what was happening to the iron content
in the atmosphere. They noticed that when they could see more
of the daytime-side disk, they say more Iron and because we’re talking about 2400K, it
had to be gaseous. Then looking at the evening terminator as
it became less visible but was still there, the iron content went down and on the dark
side of the planet and the morning terminator, they couldn’t see any iron. So they concluded that since they could see
neutral iron on the dayside and the evening terminator, but not the nightside and the
morning terminator, the gaseous iron in the atmosphere condensed as it moved to the night
side (or the dark side as I like to say) and since the nighttime temps are still pretty
hot, of around 1600k, that’s still hot enough for iron to be a liquid. And it rains. Iron. Molten Iron. Here’s what they think that would look like. This is iron condensing into rain. This wasn’t in the paper but it makes me
wonder about the oceans on WASP-76b. Would need a helluva boat to sail on molten
seas. Or maybe it’s like a giant version of Mustafar
system in Star Wars. Who knows, we could have just found the birthplace
of Darth Vader. Alright enough of that. I want to thank all Deep Astronomy Patreon
Patrons who keep these episodes coming and I want to thank all of you for watching and
as always Keep Looking Up!

14 thoughts on “WASP 76b: Hot Jupiter Exoplanet that Rains Iron at Night”

  1. There is no day/night cycle on a tidally locked planet, so it rains iron at the terminator line not the during the night.

  2. I like this video. Very interesting, with some new knowledge for me.
    I'm still curious however, as I'm sure most astrophysicists and cosmologists are, how these hot jupiters come into existence. Logically, they would form on the outside of the proto planetary disk and then migrate inwards towards their star. But we don't know for sure yet.
    And if they do, what mechanism is responsible for it? Could it happen to our own Jupiter?
    These are things that remain mysteries.
    I love investigating and trying to figure them out.
    Keep up your good work!

  3. thanks tony great video i love these new exoplanets and the information we are starting to find out about them and i am hungry to consume all info i can get on the subject ..looking forward to the stream tomorrow if its on
    cheers
    james D

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