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  • [♪ INTRO]

  • In the world of exoplanets, the easiest to find are the Hot Jupiters

  • -- large gas giants that orbit super close to their host stars.

  • For years, those were the only planets beyond

  • our solar system we could detect.

  • Even though our technology can now hunt for more

  • Earth-like worlds, studying Hot Jupiters is still

  • important for learning about how planetary systems evolve.

  • So astronomers are still hard at work learning

  • all they can about these first-gen exoworlds.

  • And this month in the Astronomical Journal,

  • they've announced that the Hubble Space telescope

  • has found the first planet with metal gas escaping

  • its atmosphere -- which offers us further insight

  • into the planetary life cycle.

  • The planet in question is known as WASP-121b,

  • whose discovery was announced back in 2016.

  • It's about 20% more massive than Jupiter,

  • but has nearly twice the diameter, so it's... puffier.

  • It's located about 900 light-years away from us

  • orbiting an F-type star, one slightly more massive,

  • hotter, and brighter than our own Sun.

  • There's been previous research studying water

  • in 121b's atmosphere, but for this study,

  • astronomers were looking for metals.

  • They did this by looking at the wavelengths of light

  • coming from the star that passed through the planet's

  • atmosphere during a transit -- those are the times when

  • the planet passed in front of the star relative to us.

  • Whatever light's missing clues us into the elements

  • that are in the atmosphere.

  • The team detected ions of magnesium and iron.

  • Finding metals in Hot Jupiter atmospheres isn't new,

  • but they usually hang out in the lower atmosphere as clouds.

  • For WASP-121b, these metals were not just located

  • in the atmosphere -- they were also found so far away

  • from the planet they're no longer bound to it by gravity.

  • The planet is shedding metal!

  • The reason for this is because WASP-121b is so stinkin' hot.

  • Its upper atmosphere clocks in at around 2500 degrees Celsius,

  • 10x hotter than any other known exoplanet.

  • And it gets to that toasty temperature because it's less than

  • four million kilometers away from its star, WASP-121a.

  • The planet's year is only 1.3 Earth days long!

  • WASP-121a emits more ultraviolet light than our Sun,

  • so it's actually heating up the planet

  • more than our Sun would.

  • The magnesium and iron also help heat the planet

  • because they absorb a lot of UV light.

  • This heating puffs up the atmosphere,

  • giving the stuff further away from the core an easier job

  • of floating off into space.

  • Basically, the hydrogen and helium in the upper atmosphere

  • are flying off the planet, taking the magnesium and iron with them.

  • This is thought to be a standard part of

  • Hot Jupiter evolution -- they form further out in the solar system,

  • but migrate inward and lose their outer atmosphere

  • as they get hotter.

  • So WASP-121b is a great piece of evidence

  • in astronomers' hunt to understand

  • the formation of gas giants.

  • But looking at things on an even bigger scale,

  • a new 3D map of the Milky Way was published last week

  • in the journal Science, which revealed that

  • our galaxy is a bit twisted.

  • It's hard to figure out how far away stuff is in space.

  • But one tried and true method since the early 1900s

  • involves a class of young, bright stars called Cepheids.

  • Those are stars that are varying in brightness over time,

  • but their variation is incredibly regular.

  • In 1912, astronomer Henrietta Swan Leavitt discovered

  • that the brightness of a Cepheid was directly tied

  • to the period of its variation.

  • The brighter the star, the longer it took to vary in brightness.

  • So by measuring a Cepheid's period, you know how bright

  • it's supposed to be.

  • By comparing that against how bright it looks

  • in the night sky, you can determine how far away it is.

  • There's a bit more to it, but that's the gist.

  • So a team of astronomers based at the

  • University of Warsaw put together data from

  • 2,431 Cepheids located within our galaxy,

  • collected by a variety of survey missions,

  • and determined their location within the Milky Way

  • relative to the Sun.

  • And when they plotted these stars in a three-dimensional map,

  • they discovered that the so-called disk of our galaxy is not flat.

  • It's warped, starting at a distance of around

  • 8 kiloparsecs from the galactic center.

  • The warping becomes steeper at about

  • 10 kiloparsecs out, up the edge of the galaxy at 20.

  • And our side of the Milky Way is warping in the

  • opposite direction as what's happening on the

  • opposite end of the galaxy.

  • In other words, if you look at it edge on,

  • our disk is vaguely s-shaped.

  • Near the edges, our disk also flares out.

  • While nearer the center it's only about 500 light-years thick,

  • out in the galactic boonies stars can be up to

  • 5000 light-years away from the galactic plane.

  • This may be due to gravitational interaction

  • with nearby galaxies, or maybe even dark matter.

  • We don't know, yet.

  • And this isn't the only evidence that our galaxy is twisted.

  • This new finding seems to match up with other research,

  • including a paper published earlier this year.

  • But having a funky shape doesn't make us special.

  • The are other spiral galaxies out there with warped disks

  • - maybe as many as half of them.

  • Even our next door neighbor, Andromeda,

  • isn't perfectly flat.

  • Since the Cepheids in this study weren't distributed evenly

  • through the Milky Way, our new 3D map of home might

  • not be 100% accurate.

  • But it's a starting point, and more data

  • should be able to refine it.

  • And yes, that may make all of that art out there

  • depicting our galaxy a little bit out of date,

  • but it's worth it to actually know more

  • about our cosmic neighborhood.

  • Thanks for watching this episode of SciShow Space News.

  • Hey, if you like space and you like pins,

  • we have something you will definitely be interested in.

  • It's our space pin of the month from DFTBA!

  • This month it's the Curiosity rover and it's just

  • SUPER cute and good.

  • It's available to pre-order through the month of August

  • and will ship in September, at which point,

  • there will be a new awesome pin.

  • And this one will never be available again.

  • Check it out at dftba.com or

  • on the merch shelf below this video!

  • And thanks!

  • [♪ OUTRO]

[♪ INTRO]

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