Venus-like exoplanet might have oxygen atmosphere, but not life

Venus-like exoplanet might have oxygen atmosphere, but not life
This artist's conception shows the rocky exoplanet GJ 1132b, located 39 light-years from Earth. New research shows that it might possess a thin, oxygen atmosphere - but no life due to its extreme heat. Credit: CfA/Dana Berry/Skyworks Digital

The distant planet GJ 1132b intrigued astronomers when it was discovered last year. Located just 39 light-years from Earth, it might have an atmosphere despite being baked to a temperature of around 450 degrees Fahrenheit. But would that atmosphere be thick and soupy or thin and wispy? New research suggests the latter is much more likely.

Harvard astronomer Laura Schaefer (Harvard-Smithsonian Center for Astrophysics, or CfA) and her colleagues examined the question of what would happen to GJ 1132b over time if it began with a steamy, water-rich atmosphere.

Orbiting so close to its star, at a distance of just 1.4 million miles, the planet is flooded with ultraviolet or UV light. UV light breaks apart water molecules into hydrogen and , both of which then can be lost into space. However, since hydrogen is lighter it escapes more readily, while oxygen lingers behind.

"On cooler planets, oxygen could be a sign of alien life and habitability. But on a hot planet like GJ 1132b, it's a sign of the exact opposite - a planet that's being baked and sterilized," said Schaefer.

Since water vapor is a greenhouse gas, the planet would have a strong greenhouse effect, amplifying the star's already intense heat. As a result, its surface could stay molten for millions of years.

A "magma ocean" would interact with the atmosphere, absorbing some of the oxygen, but how much? Only about one-tenth, according to the model created by Schaefer and her colleagues. Most of the remaining 90 percent of leftover oxygen streams off into space, however some might linger.

"This planet might be the first time we detect oxygen on a rocky planet outside the solar system," said co-author Robin Wordsworth (Harvard Paulson School of Engineering and Applied Sciences).

If any oxygen does still cling to GJ 1132b, next-generation telescopes like the Giant Magellan Telescope and James Webb Space Telescope may be able to detect and analyze it.

The magma ocean-atmosphere model could help scientists solve the puzzle of how Venus evolved over time. Venus probably began with Earthlike amounts of water, which would have been broken apart by sunlight. Yet it shows few signs of lingering oxygen. The missing oxygen problem continues to baffle astronomers.

Schaefer predicts that their model also will provide insights into other, similar exoplanets. For example, the system TRAPPIST-1 contains three that may lie in the habitable zone. Since they are cooler than GJ 1132b, they have a better chance of retaining an atmosphere.


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More information: "Predictions of the Atmospheric Composition of GJ 1132b," accepted for publication in The Astrophysical Journal: arxiv.org/abs/1607.03906
Citation: Venus-like exoplanet might have oxygen atmosphere, but not life (2016, August 18) retrieved 23 May 2019 from https://phys.org/news/2016-08-venus-like-exoplanet-oxygen-atmosphere-life.html
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Aug 18, 2016
"However, since hydrogen is lighter it escapes more readily, while oxygen lingers behind."

Hydrogen and other elements have nowhere to flee, only gravity (attractive force) is the body from which "fleeing". Where fleeing, what attracts them? Is that finally found antigravity?

Atmosphere all the stars and gaseous lower body are composed of H2, which is not fleeing. "Scientists" are not intended to, obey the laws, are important only stories without foundation.

Aug 18, 2016
@wduckss, nice trolling. Thanks for transmitting us the latest news on Discworld. Currently we have different laws of physics than those of where you live, so bear with us...

Aug 18, 2016
"a temperature of around 450 degrees Fahrenheit"

How much is that in metric units?

Aug 18, 2016

Hydrogen and other elements have nowhere to flee, only gravity (attractive force) is the body from which "fleeing". Where fleeing, what attracts them? Is that finally found antigravity?

Why yes, an electric wind.
http://phys.org/n...res.html

Aug 18, 2016
Hydrogen and other elements have nowhere to flee, only gravity (attractive force) is the body from which "fleeing". Where fleeing, what attracts them? Is that finally found antigravity?

Kinetic theory of gases, Maxwell–Boltzmann distribution.

Gas molecules collide with each other all the time (they don't stand still), and exchange kinetic energy in collisions. If you assume completely random collisions, you can derive theoretical energy probability distribution; that is, what's the likelihood of a molecule having kinetic energy in a specific range. That distribution function has no upper limit (in ideal gas theory; van der Waals attraction between gas molecules decreases probabilities of very high energies), and if kinetic energy of the molecule is higher than its gravitational potential energy, it can potentially escape the planet's gravity (given that it doesn't bump into another molecule on the way out).

Aug 18, 2016

Hydrogen and other elements have nowhere to flee, only gravity (attractive force) is the body from which "fleeing". Where fleeing, what attracts them? Is that finally found antigravity?

Why yes, an electric wind.
http://phys.org/n...res.html

Oh and also this, it is the main gas escape mechanism for worlds without magnetosphere. The simpler mechanism I described above that doesn't even require stellar "wind" is called Jeans escape, btw.

Aug 19, 2016
Stellar wind differs what should blow away and where it needs blow away?
Where is law of universality?
On exo planets near stars nothing not blown off gas.

Aug 19, 2016
2.2 gigameter = 1.093613e+007 furlong.

Aug 19, 2016
Odd, archaic units are fun, aren't they? I like reporting volumetric data in butts (2 hogsheads or 126 US gal or 477 litre). It appeals to my childishness.

Aug 20, 2016
Well, a cat furlong is a mere 8 millimeters long. It depends on the cat race actually.

Aug 20, 2016
Remaining O2 might be tied to whether or not that planet has a significant magnetic shield.

Is there a way to remotely measure such fields? Some effect on whatever O2 is left or some such?


For gas giants they are looking for radio emissions and the aurora glow around the poles that drives that. Very difficult...

Dunno if they could see some type of effect that shows up in spectra of exoplanets, which could be used for smaller planets.

Aug 20, 2016
Stellar wind differs what should blow away and where it needs blow away?
Where is law of universality?
On exo planets near stars nothing not blown off gas.


As JongDan said. thermal Jeans escape is a basic mechanism, the universal law as much as any. "One classical thermal escape mechanism is Jeans escape.[1]" [ https://en.wikipe...c_escape ]

Hydrogen and even lighter gases may be sputtered et cetera by the solar wins/CME ejections. especially on terrestrial planets that lack a strong geodynamo field. [See above link.]

Planets close to stars depend on their history, some may have lost all their gas already. The other end member of that type of object (planets with possible atmospheres close to stars) is gas giants that have remarkable amounts of gas left.

Nice to see questions, and hope these attempts to answer them helps!

Aug 22, 2016
...
Hydrogen and other elements have nowhere to flee, only gravity (attractive force) is the body from which "fleeing". Where fleeing, what attracts them? Is that finally found antigravity?

Atmosphere all the stars and gaseous lower body are composed of H2, which is not fleeing. "Scientists" are not intended to, obey the laws, are important only stories without foundation.


wduckss

It is best not to assert about something you know nothing about like you clearly have done here nor form an opinion based on total ignorance. Anyone that has studied the pretty basic physics of the behavior of gasses and gravity etc would know about what is technically called 'atmospheric escape' which obeys the known laws of physics just fine:

https://en.wikipe...c_escape
"...Atmospheric escape is the loss of planetary atmospheric gases to outer space.
...
...Thermal escape mechanisms...
...
...Significance of solar winds...
...
...( etc. )
..."


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