Hubble Space Telescope observations suggest that the exoplanets orbiting TRAPPIST-1 in the habitable zone could have water on their surfaces, while the planets closer to the star have likely lost any surface water they may have had:
An international team of scientists, led by Swiss astronomer Vincent Bourrier of the Observatoire de l'Université de Genève, used the [Hubble] space telescope to study the amount of ultraviolet light hitting the planets and measure the amount of hydrogen these worlds are venting into space. The results suggest the innermost planets, TRAPPIST-1b and TRAPPIST-1c, could have lost as much as 20 Earth-oceans-worth of water in the last eight billion years. The outer planets, however, including e, f, and g, which orbit in the habitable zone, would have lost less water, and could still retain vast stores of liquid water on the surface.
[...] The researchers used Hubble to measure the amount of ambient hydrogen floating around the TRAPPIST-1 planets as well as the intensity of ultraviolet light coming from the host star, an ultracool dwarf star. The amount of ultraviolet radiation coming from TRAPPIST-1 suggests the inner planets could have lost an enormous amount of water over the eons, something that is supported by the abundant hydrogen surrounding the planets—a possible indicator of water vapor. Most importantly, the radiation hitting the outer planets and the amount of hydrogen surrounding them suggests these worlds, similar to Earth in many ways, might still retain atmospheric water vapor and even liquid water on the surface.
[...] Whether or not these planets could actually support life is still an open question. First of all, the observations from Hubble are not conclusive, and further observations from other observatories as well as computer simulations are required to support or dispute the possibility of water on the TRAPPIST-1 planets.
"While our results suggest that the outer planets are the best candidates to search for water with the upcoming James Webb Space Telescope, they also highlight the need for theoretical studies and complementary observations at all wavelengths to determine the nature of the TRAPPIST-1 planets and their potential habitability," says Bourrier.
Also at Hubble News and Space.com.
Temporal Evolution of the High-Energy Irradiation and Water Content of TRAPPIST-1 Exoplanets
Related Stories
Star's magnetic field could turn habitable-zone planets into magma soup
[A] team of European researchers has identified something else that could have an immense effect on habitability: the star's magnetic field. Under the right conditions, planets close to a star will experience a strong but variable magnetic field, which can cause induction heating. In the case of one system with several habitable zone planets, the induction heating could be strong enough to convert them into oceans of magma.
[...] The European team behind the new report focused on M dwarf stars. Because these are small, relatively cool objects, their habitable zones are close to the star and well within the region where the star's magnetic field is quite strong. They also have magnetic fields that are strong to begin with, sometimes in the area of thousands of Gauss. The magnetic field of our Sun is typically 10 to 1,000 times weaker.
Not all M dwarfs rotate quickly enough for this to matter. Proxima Centauri, which hosts the closest known exoplanet, takes more than 80 days to complete a rotation. But there is a nearby M dwarf that completes a rotation in only three days: TRAPPIST-1, which hosts at least seven planets, three of them in the habitable zone. So, the team decided to model how much of an effect induction heating might have on these bodies.
[...] For TRAPPIST-1c, the third planet out from the star, induction heating reaches more than 60 percent of the heat released in the planet by radioactive decay. That's enough to melt the entire surface, turning it into a magma ocean in nearly all the different model conditions sampled. The same conditions are likely on TRAPPIST-1d, the one in the habitable zone, where induction heating can be above half the amount of heat released by radioactive decay.
Red dwarf exolife killer or a way to expand the habitable zone further out?
Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction heating (DOI: 10.1038/s41550-017-0284-0) (DX)
Previously: Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
Powerful Solar Flares Found at TRAPPIST-1 Could Dim Chances for Life
TRAPPIST-1h Orbital Details Confirmed
TRAPPIST-1 Older than Our Solar System
Hubble Observations Suggest TRAPPIST-1 Exoplanets Could Have Water
TRAPPIST-1's exoplanets appear to have migrated closer to TRAPPIST-1 over time until they reached their current orbits. This migration appears to have allowed them to retain too much water to support life:
What [the ASU-Vanderbilt team] found through their analyses was that the relatively "dry" inner planets ("b" and "c") were consistent with having less than 15 percent water by mass (for comparison, Earth is 0.02 percent water by mass). The outer planets ("f" and "g") were consistent with having more than 50 percent water by mass. This equates to the water of hundreds of Earth-oceans. The masses of the TRAPPIST-1 planets continue to be refined, so these proportions must be considered estimates for now, but the general trends seem clear.
"What we are seeing for the first time are Earth-sized planets that have a lot of water or ice on them," said Steven Desch, ASU astrophysicist and contributing author.
But the researchers also found that the ice-rich TRAPPIST-1 planets are much closer to their host star than the ice line. The "ice line" in any solar system, including TRAPPIST-1's, is the distance from the star beyond which water exists as ice and can be accreted into a planet; inside the ice line water exists as vapor and will not be accreted. Through their analyses, the team determined that the TRAPPIST-1 planets must have formed much farther from their star, beyond the ice line, and migrated in to their current orbits close to the host star.
[...] "We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live," Hinkel explained. "However, a planet that is a water world, or one that doesn't have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life."
Also at Phys.org.
Inward migration of the TRAPPIST-1 planets as inferred from their water-rich compositions (DOI: 10.1038/s41550-018-0411-6) (DX) (arXiv)
Related: Powerful Solar Flares Found at TRAPPIST-1 Could Dim Chances for Life
TRAPPIST-1 Older than Our Solar System
Hubble Observations Suggest TRAPPIST-1 Exoplanets Could Have Water
Induction Heating Could Cause TRAPPIST-1 Exoplanets to Melt
Another TRAPPIST-1 Habitability Study
Alien Life Could Thrive On Four Earth-Like Planets Close To The Solar System, Says Study
Alien life could be evolving right now on some of the nearest exoplanets to our solar system, claim scientists at Cornell University in Ithaca, New York. Their proof is you.
It's been presumed that the high levels of radiation known to be bombarding many of the rocky Earth-like exoplanets discovered so far by astronomers precludes life, but that theory is turned on its head by new research published [open, DOI: 10.1093/mnras/stz724] [DX] in Monthly Notices of the Royal Astronomical Society.
In "Lessons from Early Earth: UV Surface Radiation Should Not Limit the Habitability of Active M Star System", the authors say that all of life on Earth today evolved from creatures that thrived during an era of much higher levels of UV radiation assault. So why not life on alien worlds? It also poses another question: does the evolution of life actually require high levels of radiation?
The exoplanets studied are Proxima b, TRAPPIST-1e, Ross 128 b, and LHS 1140 b.
Related: ESO Confirms Reports of Proxima Centauri Exoplanet
Proxima b May Have Oceans
Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
Possible Habitable Planet, LHS 1140b, Only 40 Light Years Away
An Earth-Like Atmosphere May Not Survive the Radiation in Proxima b's Orbit
Hubble Observations Suggest TRAPPIST-1 Exoplanets Could Have Water
Ross 128b: A Newly Discovered "Earth-Like" Exoplanet Orbiting a Less Active Red Dwarf
Another TRAPPIST-1 Habitability Study
(Score: 0) by Anonymous Coward on Friday September 01 2017, @12:49PM (8 children)
Why use this weasel wording like "X suggests Y could Z"? It looks pretty shady, not to mention unsophisticated. Its like something a person would write if they were certain about their conclusions.
(Score: 4, Interesting) by maxwell demon on Friday September 01 2017, @02:19PM (1 child)
Maybe the data gives this as the most probable, but not as the only possibility? I mean, ordinary people like to jump to conclusions, but scientists are typically more careful.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Saturday September 02 2017, @07:20PM
This title is not using weasel wording: "Hubble Spots Possible Evidence of Water on Earth-Sized TRAPPIST-1 Planets"
http://www.popularmechanics.com/space/a28018/hubble-spots-possible-evidence-of-water-on-earth-sized-trappist-1-planets/ [popularmechanics.com]
It correctly conveys uncertainty without a bunch of "suggests", "coulds", "woulds", 'maybes", etc. One "possibly" is enough.
(Score: 1, Interesting) by Anonymous Coward on Friday September 01 2017, @03:11PM
I think what they are saying is that X are consistent with the hypothesis that Y Zs, but there could be other explanations for X besides Y Z-ing.
Essentially, X doesn't disprove the hypothesis that Y Zs, more studies should be used to confirm that Y does, in fact, Z.
At least that is how I read X suggests that Y could Z.
(Score: 2) by takyon on Friday September 01 2017, @04:30PM
Weasel wording = accurate wording.
It turns out it is tough to tell what's going on 39.5 light years away.
It would be shady if I wrote "Water Found on TRAPPIST-1 Exoplanets".
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: -1, Troll) by MyOpinion on Friday September 01 2017, @08:22PM (2 children)
Because the whole operation is a hoax on your tax money, is one theory: nobody, not one, _dares_ assume responsibility for the "Hubble Space Telescope". It is a hot potato ready to burst. You may proceed and call the team on the phone and hear it for yourself.
By the sub-director's own admission, NASA is NOT tracking Hubble, which to me sounds like a fancy way of saying "we have no idea where it is".
"Hubble" presumably has a much higher altitude than the Atlantis mission that serviced it. How did it put itself back into that orbit without propulsion? It got no boost from Atlantis.
"Hubble" cannot be seen from the "ISS" either. How so? It should be trivial to point one of those potent lenses out of a window and shoot.
The only person that I know of claiming to actually track "Hubble" is a (rather unconvincing) youtube channel named "Live Astronomy". No backing up from professional scientists.
To me it seems that "Hubble" is, at best, the "stratospheric" aircraft-mounted infrared telescope [usra.edu]. At worst, this is complete and total malfeasance on the back of the US and the international taxpayer.
Trivia: NASA's budget is more than FIFTY (50) million dollars per day.
Truth is like a Lion: you need not defend it; let it loose, and it defends itself. https://discord.gg/3FScNwc
(Score: 1, Informative) by Anonymous Coward on Friday September 01 2017, @08:45PM (1 child)
http://www.satview.org/?sat_id=20580U [satview.org]
(Score: 0) by MyOpinion on Saturday September 02 2017, @08:14PM
So your argument is that "Hubble" exists because a tracking webpage exists?
How about Tate's satellite webcam [tate.org.uk]? Does this look legit to you?
Truth is like a Lion: you need not defend it; let it loose, and it defends itself. https://discord.gg/3FScNwc
(Score: 0) by Anonymous Coward on Saturday September 02 2017, @01:19AM
Nothing weasely at all. There is just a vast shocking chasm between what is presented ("artist's impression") and the actual reality of the data or observation.
See this Youtube video: "Why Astronomers Love Python and You Should Too" (32 min)
https://youtu.be/W9dwGZ6yY0k [youtu.be] ... about 4 minutes in. Watch the whole thing, it is well worth the time!
(Score: 3, Funny) by lx on Friday September 01 2017, @01:03PM (1 child)
On TRAPPIST-1 planets I expected there to be beer [wikipedia.org].
(Score: 2) by fritsd on Friday September 01 2017, @04:30PM
That would be a good proposal for the renaming-celestial-objects-committee people:
Trappist-1a => Chimay Bleue
Trappist-1b => Westmalle Tripel
Trappist-1c => Chimay Rouge
Trappist-1d => Westmalle Dubbel
Trappist-1e => Orval
Trappist-1f => La Trappe Dubbel
Trappist-1g => Rochefort 6
Trappist-1h => Duvel
... etc. etc. (OK I admit I can't think of any more ;-) )