First traces of atmospheric water vapour detected on 'super-Earth' in habitable zone - CBC.ca - Canadanewsmedia
Connect with us

Science

First traces of atmospheric water vapour detected on 'super-Earth' in habitable zone – CBC.ca

Published

on


Roughly 111 light-years away, toward the constellation of Leo, lies a dim star less than half the mass of our sun, with two planets in close orbit. Now, astronomers have revealed that one of those planets has an atmosphere containing water vapour.

The discovery, published Wednesday in the journal Nature, is the first of its kind. While other, larger, gaseous planets — called hot Jupiters — have revealed some hints about the chemical elements contained in their atmospheres, this is the first time water vapour has been detected on a potentially habitable planet, an historic first.

The planet is called K2-18 b, and orbits its parent star — K2-18 — at roughly 0.14 astronomical units (one AU is the distance from our sun to Earth). Because it is so much closer to its parent star, it orbits quite quickly: one year on K2-18 b is equal to just 33 days here on Earth.

K2-18 b is roughly eight times the mass of Earth and about twice the radius, making it a super-Earth or sub-Neptune in the somewhat loose classification of exoplanets.

But what’s most important is that K2-18 b resides within the star’s habitable zone, a region around a star where liquid water can exist on a planet’s surface. Depending on what kind of star it is, the distance varies. In this case, K2-18 b orbits the dwarf star within what would be Mercury’s orbit in our solar system. 

The search is on

K2-18 b was discovered in 2015, and due to its proximity to Earth and its dim star, it was considered a good candidate for detecting an atmosphere. The team of astrophysicists examined data from the Hubble Space Telescope collected in 2016 and 2017. While not ideal for detecting a wide range of molecular elements in distant exoplanets, Hubble is, however, capable of detecting water vapour. 

Astronomers made the discovery of atmospheric water vapour in K2-18 b’s atmosphere using 2016 and 2017 data from the Hubble Space Telescope. (NASA)

The team additionally used spectroscopic data (where light is broken up into its particular molecular elements). What they found was strong evidence that K2-18 b had water vapour in its atmosphere.

Running several models, they concluded that three conditions were equally likely to account for the water vapour detected: that it could be a type of “waterworld,” with an abundance of water; that it could contain gases such as hydrogen and nitrogen, with a little water; and finally, that it could contain very little water, but with high-altitude clouds.

Those three models mean that the water that was detected could range from 0.01 per cent to 50 per cent.

It’s a large range, to be sure.

“We don’t really know how much water there is,” said Angelos Tsiaras, lead author of the study. “This is related to the size of the atmosphere. We need wider wavelengths to cover it.”

Hubble finds water vapour on distant exoplanet

[embedded content]

While Hubble may only be able to scan narrow wavelengths in its observations, a new space telescope is set to revolutionize astronomy: the James Webb Space Telescope. That, the authors say, may blow the search for atmospheres around potentially habitable exoplanets wide open.

One small step

The detection of water vapour around a potentially habitable planet is being hailed as a first step in what will become a wider understanding of exoplanets.

“The first evidence for an atmospheric feature in a habitable-zone planet is just fantastic,” said exoplanetary researcher Ryan Cloutier of the Center for Astrophysics at Harvard University. As a PhD student at the University of Toronto, he lead the research that not only determined that K2-18 b was a super-Earth, but that there was another planet in the system. “Habitable-zone planets are the holy grail for atmospheric studies.”

Exoplanets that are Jupiter-sized or larger are easier to find than smaller ones, particularly those closer to the size of Earth. So, if simply finding them is so challenging, determining the molecules in their atmospheres is even more difficult. 

But finding water vapour alone in an atmosphere of a potentially habitable exoplanet doesn’t mean life exists on K2-18 b. 

And water vapour doesn’t necessarily mean water exists on the surface. 

The temperature of the planet is roughly –73 C to 46 C, which is similar to Earth. The range is so large because of various unknown factors, including the temperature of the star and the distance between the star and the planet and the planet’s atmosphere and pressure, which is why it’s unclear if water exists on the surface.

However, the James Webb Space Telescope — which is scheduled to launch in 2021 — will be capable of finding other molecules such as methane and ozone, which could add more evidence to the potential of life on an exoplanet, though it won’t be definitive proof of life.

The James Webb Space Telescope is the scientific successor to NASA’s Hubble Space Telescope, and is scheduled to launch in 2021. (NASA/Desiree Stover)

“I think it’s very cool, and it’s a step in the right direction. These objects are incredibly enigmatic, the so-called sub-Neptunes … and we have no idea what they are,” said Sara Seager, an MIT exoplanet researcher originally from Toronto, who was not involved in the study. “We really want to understand this type of planet, and we’re hoping the atmospheres will provide some clue as to what they are.”

Tsiaras is optimistic about the future of exoplanet habitability research.

“It’s always one small step at a time,” said Tsiaras. “This time it was the first atmosphere, then it will be the first methane, then probably, why not, some detection of ozone. So one small step at a time.”

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Oxygen on Mars Is Behaving in a Way Scientists Can't Explain – ScienceAlert

Published

on

By


Atmospheric gases on Mars sure provide us with plenty of mystery. First, there was that business with the disappearing, reappearing methane. Now, oxygen levels have been observed rising and falling over the Gale Crater, by amounts that just don’t fit any known chemical processes.

The data comes from Curiosity, the Mars rover that’s been making its slow and methodical trek across the crater floor and up the foot of Mount Sharp in the centre of it.

The robot isn’t just looking down at the rocks beneath its treads; Curiosity also takes readings of the Martian atmosphere to measure the seasonal atmospheric changes. It’s been up there for three Mars years now (that’s six Earth years), and scientists poring over the measurements have noticed that oxygen in the planet’s atmosphere isn’t behaving entirely as expected.

There actually isn’t all that much oxygen on Mars. Most of its thin atmosphere (95 percent by volume) is carbon dioxide, or CO2. The rest is made up of 2.6 percent molecular nitrogen (N2), 1.9 percent argon (Ar), 0.16 percent molecular oxygen (O2), and 0.06 percent carbon monoxide (CO).

(Earth’s atmosphere, by contrast, is mostly nitrogen, at 78.09 percent by volume, and 20.95 percent oxygen.)

On Mars, atmospheric pressure changes over the course of the year. On the winter hemisphere, CO2 freezes over the pole, which causes the pressure to drop across the hemisphere. This results in a hemisphere-to-hemisphere redistribution of gases to equalise atmospheric pressure planet-wide.

In spring, when the polar caps melt and release the CO2, the opposite effect occurs: pressure initially rises in that hemisphere, then evens out as gases are redistributed towards the winter hemisphere.

So, the fluctuations of the other gases are predictable in proportion to the CO2 levels. Or at least, they should be. In the case of nitrogen and argon, it is – these gases have been behaving more or less exactly as expected. But oxygen? Nope.

During spring and summer, oxygen rose by around 30 percent, dropping back to normal levels in autumn. This happened every year, but since the amount by which the oxygen rises varies from year to year, it seems like something is adding the oxygen, and then taking it away again.

There is no known process that can produce this result.

The obvious question for such an odd measurement was whether there could be something wrong with the Quadrupole Mass Spectrometer instrument or software. Several checks saw that it was all working fine.

Another possibility was whether the oxygen could be produced by water or carbon dioxide somehow breaking apart in the atmosphere. This was quickly ruled out too – there’s not nearly enough water in the Martian atmosphere, and CO2 breaks down too slowly to fit the observed fluctuations.

Now, Martian soil does contain a lot of oxygen. But the conditions required to release it have not been observed – and that wouldn’t explain where it disappears to each year. The process whereby solar radiation breaks apart oxygen and it dissipates into space is likewise too slow.

“We’re struggling to explain this,” said planetary scientist Melissa Trainer of NASA’s Goddard Space Flight Center.

“The fact that the oxygen behaviour isn’t perfectly repeatable every season makes us think that it’s not an issue that has to do with atmospheric dynamics. It has to be some chemical source and sink that we can’t yet account for.”

But there is one clue. The methane. It, too, rises dramatically over Mars’ summer months, increasing by up to 60 percent. Sometimes the methane and oxygen levels even seem to rise in tandem. It’s possible that whatever it is that causes the methane fluctuations is also causing the oxygen fluctuations.

What that could be is still a huge question. Both gases can be produced through organic processes – that is, life – and both can be produced through geological processes.

We don’t, as yet, have any evidence that there is life on Mars, but nor can it be ruled out as a cause. (Mars 2020 is going to look for fossils, so maybe we’ll find out soon.)

However, the team believes it is much more likely to be geological.

“We have not been able to come up with one process yet that produces the amount of oxygen we need,” said astronomer Tim McConnochie of the University of Maryland.

“But we think it has to be something in the surface soil that changes seasonally because there aren’t enough available oxygen atoms in the atmosphere to create the behaviour we see.” 

So… any ideas?

The research has been published in the Journal of Geophysical Research: Planets.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Mini Mercury skips across sun’s vast glare in rare transit – Fernie Free Press

Published

on

By


Mini Mercury skipped across the vast, glaring face of the sun Monday in a rare celestial transit.

Stargazers used solar-filtered binoculars and telescopes to spot Mercury — a tiny black dot — as it passed directly between Earth and the sun on Monday.

The eastern U.S. and Canada got the whole 5 1/2-hour show, weather permitting, along with Central and South America. The rest of the world, except for Asia and Australia, got just a sampling.

Mercury is the solar system’s smallest, innermost planet. The next transit isn’t until 2032, and North America won’t get another shot until 2049.

In Maryland, clouds prevented NASA solar astrophysicist Alex Young from getting a clear peek. Live coverage was provided by observatories including NASA’s orbiting Solar Dynamics Observatory.

“It’s a bummer, but the whole event was still great,” Young wrote in an email. “Both getting to see it from space and sharing it with people all over the country and world.”

At Cape Canaveral, space buffs got a two-for-one. As Mercury’s silhouette graced the morning sun, SpaceX launched 60 small satellites for global internet service, part of the company’s growing Starlink constellation in orbit.

ALSO READ: ‘Very surreal’: B.C. students help design space colony in NASA-backed competition

___

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

Marcia Dunn, The Associated Press


Like us on Facebook and follow us on Twitter.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

A Star Ejected from the Milky Way's 'Heart of Darkness' Has Reached a Mind-Blowing Speed – Space.com

Published

on

By


As humankind’s ancestors were learning to walk upright, a star was launched out of the supermassive black hole at the center of our galaxy at a staggering 3.7 million mph (6 million km/h). 

Five million years after this dramatic ejection, a group of researchers, led by Sergey Koposov of Carnegie Mellon University’s McWilliams Center for Cosmology, has spotted the star, known as S5-HVS1, in the Crane-shaped constellation Grus. The star was spotted traveling relatively close to Earth (29,000 light-years away) at unprecedented, searing speeds — about 10 times faster than most stars in our galaxy. 

“The velocity of the discovered star is so high that it will inevitably leave the galaxy and never return,” Douglas Boubert, a researcher at the University of Oxford and a co-author on the study, said in a statement

Related: Top 10 Star Mysteries of All Time

An artist’s impression of te star S5-HVS1 being ejected by the Milky Way galaxy’s supermassive black hole, Sagittarius A*.

(Image credit: James Josephides (Swinburne Astronomy Productions))

“This is super exciting, as we have long suspected that black holes can eject stars with very high velocities. However, we never had an unambiguous association of such a fast star with the galactic center,” Koposov said in the statement. 

The star was discovered with observations from the Anglo-Australian Telescope (AAT), a 12.8-foot (3.9-meter) telescope, and the European Space Agency’s Gaia satellite. The discovery was made as part of the Southern Stellar Stream Spectroscopic Survey (S5), a collaboration of astronomers from Chile, the U.S., the U.K. and Australia. 

Now that the star has been spotted, researchers could track the star back to Sagittarius A*, the black hole at the center of the Milky Way. It also serves as an incredible example of the Hills Mechanism, proposed by astronomer Jack Hills 30 years ago, in which stars are ejected from the centers of galaxies at high speeds after an interaction between a binary-star system and the black hole at the center of the galaxy.

The location and direction of the star S5-HVS1 in the night sky. The star is rocketing away from the center of our galaxy.

(Image credit: Sergey Koposov)

“This is the first clear demonstration of the Hills Mechanism in action,” Ting Li, a fellow  at the Carnegie Observatories and Princeton University who led the S5 collaboration, said in the statement. “Seeing this star is really amazing as we know it must have formed in the galactic center, a place very different to our local environment. It is a visitor from a strange land.”

“While the main science goal of S5 is to probe the stellar streams — disrupting dwarf galaxies and globular clusters — we dedicated spare resources of the instrument to searching for interesting targets in the Milky Way, and voila, we found something amazing for ‘free.’ With our future observations, hopefully we will find even more!” Kyler Kuehn, deputy director of technology at the Lowell Observatory who is part of the S5 executive committee, added in the statement.

This discovery was published in a study on Nov. 4 in the journal the Monthly Notices of the Royal Astronomical Society. 

Follow Chelsea Gohd on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

Let’s block ads! (Why?)



Source link

Continue Reading

Trending