Hubble detects exoplanet with glowing water atmosphere

August 2, 2017, University of Exeter
Credit: Engine House VFX, At-Bristol Science Centre, University of Exeter

Scientists have found the strongest evidence to date for a stratosphere on an enormous planet outside our solar system, with an atmosphere hot enough to boil iron.

An international team of researchers, led by the University of Exeter, made the new discovery by observing glowing in the of the WASP-121b with NASA's Hubble Space Telescope.

In order to study the gas giant's stratosphere - a layer of atmosphere where increases with higher altitudes - scientists used spectroscopy to analyse how the planet's brightness changed at different wavelengths of light.

Water vapour in the planet's atmosphere, for example, behaves in predictable ways in response to different wavelengths of light, depending on the temperature of the water. At cooler temperatures, in the planet's upper atmosphere blocks light of specific wavelengths radiating from deeper layers towards space. But at higher temperatures, the water molecules in the upper atmosphere glow at these wavelengths instead.

The phenomenon is similar to what happens with fireworks, which get their colours from chemicals emitting light. When metallic substances are heated and vaporized, their electrons move into higher energy states. Depending on the material, these electrons will emit light at specific wavelengths as they lose energy: sodium produces orange-yellow and strontium produces red in this process, for example.

The water molecules in the atmosphere of WASP-121b similarly give off radiation as they lose energy, but it is in the form of infrared light, which the human eye is unable to detect.

The research is published in leading scientific journal Nature.

"Theoretical models have suggested that stratospheres may define a special class of ultra-hot exoplanets, with important implications for the atmospheric physics and chemistry," said Dr Tom Evans, lead author and research fellow at the University of Exeter. "When we pointed Hubble at WASP-121b, we saw glowing water molecules, implying that the planet has a strong stratosphere."

WASP-121b, located approximately 900 light years from Earth, is a exoplanet commonly referred to as a 'hot Jupiter', although with a greater mass and radius than Jupiter, making it much puffier. The exoplanet orbits its host star every 1.3 days, and is around the closest distance it could be before the star's gravity would start ripping it apart.

This close proximity also means that the top of the atmosphere is heated to a blazing hot 2,500 degrees Celsius - the temperature at which iron exists in gas rather than solid form.

Credit: NASA, ESA, and G. Bacon (STSci)

In Earth's stratosphere, ozone traps ultraviolet radiation from the sun, which raises the temperature of this layer of atmosphere. Other solar system bodies have stratospheres, too - methane is responsible for heating in the stratospheres of Jupiter and Saturn's moon Titan, for example. In solar system planets, the change in temperature within a stratosphere is typically less than 100 degrees Celsius. However, on WASP-121b, the temperature in the stratosphere rises by 1000 Celsius.

"We've measured a strong rise in the temperature of WASP-121b's atmosphere at higher altitudes, but we don't yet know what's causing this dramatic heating," says Nikolay Nikolov, co-author and research fellow at the University of Exeter. "We hope to address this mystery with upcoming observations at other wavelengths."

Vanadium oxide and titanium oxide gases are candidate heat sources, as they strongly absorb starlight at visible wavelengths, similar to ozone absorbing UV radiation. These compounds are expected to be present in only the hottest of hot Jupiters, such as WASP-121b, as high temperatures are required to keep them in the gaseous state.

Indeed, vanadium oxide and titanium oxide are commonly seen in brown dwarfs, 'failed stars' that have some commonalities with exoplanets.

Previous research spanning the past decade has indicated possible evidence for stratospheres on other exoplanets, but this is the first time that glowing water molecules have been detected, the clearest signal yet for an exoplanet stratosphere.

It is one of the first results to come out of a new observing program being carried out by an international team of scientists, led by Associate Professor David Sing at the University of Exeter and Dr. Mercedes Lopez-Mórales at the Smithsonian Institution. The program has been awarded 800 hours to study and compare 20 different exoplanets, representing one of the largest time allocations for a single program in the entire 27 year history of Hubble.

"This new research is the smoking gun evidence scientists have been searching for when studying hot exoplanets. We have discovered this hot Jupiter has a , a common feature seen in most of our solar system planets." says Professor David Sing, co-author and Associate Professor of Astrophysics at the University of Exeter.

"It's a truly exciting find as we're seeing dramatic differences planet-to-planet which is giving valuable clues in figuring out how planets behave under different conditions, and we're only just scratching the surface of all the new Hubble data."

NASA's forthcoming James Webb Space Telescope will be able to follow up on the atmospheres of planets like WASP-121b with higher sensitivity than any telescope currently in space.

"This super-hot exoplanet is going to be a benchmark for our atmospheric models, and will be a great observational target moving into the Webb era," said Hannah Wakeford, co-author and Research Fellow at the University of Exeter.

Explore further: Hubble detects 'sunscreen' layer on distant planet

More information: An ultrahot gas- giant exoplanet with a stratosphere, Nature (2017). nature.com/articles/doi:10.1038/nature23266

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Chris_Reeve
Aug 02, 2017
This comment has been removed by a moderator.
wduckss
3.7 / 5 (3) Aug 02, 2017
Hottest Kepler-70b.. 0.440 Earth 7.143°K
WASP-33b.. 4,59 Jupiter 2.451°K
WASP-121b.. 1.183 J 2.358
WASP-87b.. 2.18 2.322
WASP-12b.. 1.404 2.319
HIP 78530 b.. 24 2.700
Kepler-13b.. 6.6 2.750
DH Tauri b.. 12 2.750
PSR J1719-1438 b.. 1.2 5.375
KOI-368.01.. 2.1 3.060
KOI-55 C.. 0,0021 6.319
CT Chamaeleontis b.. 10,5-17 2.500
HAT-P-7b.. 1.709 2.733
OGLE2-TR-L9.. 4.34 2.154.6
WASP-48 b.. 0.98 2.030
UScoCTIO 108 b..14 2.350
WASP-103 b.. 1.47.. 2.508
Kepler-10 b..0,010475 2.169
WASP-100b..1.69 2.190
WASP-72b..1.01 2.210
WASP-18 b..1,165 (10.43) 2.187,5
Oph 11 B..21 2.478
WASP-78 b..1.16 2.006.7
KELT-7 b..1.28 2.048
WASP-111 b..1.83 2.140
+ Semi major axis AU/ Parent star spectral typ on: https://www.acade...rect.doc
Captain Stumpy
not rated yet Aug 07, 2017
@f*cking illiterate eu pseudoscience cult socks hannes/reeve
Article is entirely discussing plasma, but notice that it not once mentions that state of matter directly
for starters the article is about (let me quote it):
a stratosphere on an enormous planet outside our solar system, with an atmosphere
this is in the first sentence, and it's validated by referencing the study linked

more to the point, it talks about atmospheric gasses - you know, like Earth has atmospheric gasses that are (gasp) *not plasma*! (ohs Nose!)

that kinda makes you look like an illiterate idiot jumping to conclusions! or someone who didn't read the article OR the study!

worse still, per the study
Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere
holy sh*t! that's right!
atmospheric gasses!
like nitrogen, oxygen or other similar gasses not in a plasma state!

:O

Captain Stumpy
not rated yet Aug 07, 2017
@eu pseudoscience illiterate multi-sock hannes/reeve cont'd
If a person is not even aware that this is matter in the plasma state, then they surely also do not understand that the correct way to study the phenomenon is through plasma electrochemistry
and if a person doesn't actually even take the time to read the article or study then they're not aware of the composition and content of the study

so when you pop off with stupid anti-MS astrophysicist quotes about your interpretation of the data when you're clearly not able to comprehend that the paper talks about, say, gaseous vanadium oxide and titanium oxide...

this is one reason you're considered a very stupid troll
you obviously didn't bother to read the article or the study abstract

it's either that or you are so wrapped up in your cult beliefs that you can't comprehend that not all gasses are plasma's

this is easily proven by taking room samples from sea level to pikes peak

epic fail for you and the eu

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