All of the planets in the Trappist-1 system are tidally locked so their dark sides are not receiving direct sunlight.  The effects of solar flares would be transmitted through the atmosphere.  

Yes, I am assuming that life is DNA-RNA based; basically, the same type of life found at hydrothermal vents in Earth's ocean.  From observations of Io in the Jupiter system, I think we can assume that, if there is an ocean, it contains hydrothermal vents because the tidal effects are greater for planets at Trappist-1 than they are for the moons of Jupiter.  This comparison actually raises another question:  Are the tidal effects so great that the surface is molten?  If so, would this be true for all of the Trappist-1 planets, or just the inner ones?  Even if the surface is molten, if the oceans are deep enough, they might sit atop a layer of compressed steam and be heated from the bottom rather than from the top as Earth's oceans are.

Nobody knows how deep the water is or even if there is water, but the tides are going to change that depth by hundreds of meters every few days.  There are hydrothermal vents on Earth 2500 meters deep, and probably even deeper ones that we haven't discovered yet, so the creatures should be able to withstand the fluctuations in pressure due to the greater tides on Trappist-1 planets.  But wild swings in pressure over a matter of days is something else that makes Trappist-1 oceans (if they exist) different than Earth's oceans.

2. As you should know, TRAPPIST-1 h has already been confimed at 18.76 days from K2 observations (Luger+2017, https://arxiv.org/abs/1703.04166). As of now, not any planet has been announced at ~14 days.

Kenneth Towe-

You write, "Eventually 'life' anywhere will have to greet the UV flux from its Sun to manufacture its 'food'...oxygenic photosynthesis."

I don't think that is true.  The base of the food chain at hydrothermal vents are bacteria that make no use of photosynthesis but rely entirely on the heat and CO2 from the vent.

Adrien Coffinet-

You write, "As you should know, TRAPPIST-1 h has already been confimed at 18.76 days"

No, I did not know that.  The paper that you link to by Luger et. al. is dated 12 Mar 2017, which is two weeks earlier than when I wrote my paper on 26 Mar 2017.  But I was unaware of it.  I got my information from www.trappist.one and from the NASA website.  Both of those sources are still saying 20 days, the former giving a range of -6 to +15 days and that latter just saying "about."

Okay, though hunkering down until one runs out of food is not the same thing as asking where an organism evolved.

I am out of my depth here - I am not a paleobiologist - but I will say this:  Your hot little ponds and your rival's deep-sea hot springs may well be the same place once a month.  I haven't calculated the height of the tides on Trappist-1C (Has anyone?) but they have got to be hundreds of meters high.  Similarly, when the moon was first formed, it was much closer to Earth than it is today, the month was only a few days and the tides were much higher - basically the same thing that Trappist-1C experiences as Trappist-1B passes by it.  In both the early Earth and the modern Trappist-1C, the ocean must have washed tens and perhaps hundreds of kilometers inland every few days.  So the same vent was rapidly alternating between being a hot pond and a deep-sea hot spring. 

Trappist-1B laps Trappist-1C every four Earth days and, at its nearest approach, has about 27 time the gravitational pull on Trappist-1C's oceans as the moon does on our oceans today.  For our moon to affect tides this much, it would have to be over five times closer to Earth than it is today; indeed, it was this close at the time when life first appeared on Earth.

My vision for Trappist-1C and what the entrants to my writing contest are expected to write about - Refutations are welcome too! - is that there is a shallow ocean spanning the entire dark side of the planet.  The sunny side is an insufferably hot desert.  At the terminal line, there are strong winds and high waters flowing towards the sunny side of the planet.  The farther this water flows into the sunny side, the hotter it gets until it has all boiled away after a few hundred kilometers across the terminal line.  Simultaneously, there are high altitude rain clouds moving towards the dark side and, hundreds of kilometers across the terminal line, the ocean is pelted with torrential downpours.

Thus, the terminal line is a tempestuous place with high winds, high water and torrential rains.  This is caused by the temperature gradient and would happen even in the absence of other planets.  But, every four Earth days, Trappist-1B passes by and causes the water flowing across the terminal line to rise by hundreds of meters, causing a flooding event that would make Noah blush.  Momentarily, water flows many hundreds of kilometers into the sunny side of the planet before it almost instantaneously evaporates when it hits the sun-baked sand.

This weather pattern is further complicated by the presence of the outer planets.  Trappist-1D, 1E, 1F and 1G pass by every 4.0, 6.0, 4.0, 3.3 and 3.0 days and give the ocean a gravitational tug in the opposite direction from that of 1B with a force 5.6, 2.0, 0.75 and 0.8 times that of our moon.  My writing contest is mostly meant for middle- and high-school students, but there is also a category for adults (ambitious students can enter as adults if they wish) and a detailed mathematical model of the tides on Trappist-1C would be a suitable topic for an adult submission.

And, this being fiction, the octopii developed intelligence and will seriously kick our butts if we ever make the 12 parsec trip and drop a submarine into their ocean!

Of course it is speculation - everything said about Trappist-1 is until we get more data.  The question is whether my scenario is possible or impossible.  If you think it is impossible, then explain the logical flaw.

Hi Victor. 

Thank you kindly for taking an interest in my recent paper on the climates of the TRAPPIST-1 system.  Planets b, c, and d are most likely too hot to have stable oceans on their surface.  These planets would enter a runaway greenhouse state, and would lose their oceans to space.  By my calculations, planets b, c, and d should be hot, dry, and uninhabitable at the surface.

Planet e poses the best chance for habitable Earth-like surface conditions, given appropriate greenhouse gases.  Planets f and beyond are likely too cold and exist as icy, snowball planets. However, they could still maintain oceans trapped beneath their ice sheets, kept warm due to tidal heating.

Of course, one big caveat in all of this is that we are assuming that these planets have water on them to begin with, a characteristic itself that is challenged by the radiation environments around M-dwarf stars.

But, to your original question, it would be more realistic to ask if life can exist at hydrothermal vents on planets e and beyond.  Your question regarding exo-hydrothermal communities is very pertinent considering the recent news about Enceladus as well.

Cheers,

Eric

Eric Wolf-

Thank you for taking the time to look at the scenario I have created for my student writing contest.  I started this contest last month before reading your paper and can easily change it from Trappist-1C to Trappist-1E.

There is a lot about the Trappist-1 system that is still unknown, but hopefully we will learn more next year when the James Webb telescope goes online.  In the meantime, there is a lot of excitement among students and I want to give them the opportunity to write on this subject, but without totally misleading them with an unrealistic scenario.

1. Yes, I think that life at hydrothermal vents on Trappist-1C could survive frequent solar flares. The fact that the solar flares "probably continuously alters the atmospheres of the orbiting exoplanets" is not promising. However, given the right thickness of the water-ice crust and strength and potential of the planet's magnetic field, it is possible that any living organisms underwater on the dark side could remain unharmed.

2. Seems reasonable, and highly plausible. Formation of those worlds would be an interesting contrast to the first 7. 

Victor - I'm enjoying this discussion and your ideas, speculation or not.

An issue with flaring is definitely the atmosphere, since it could be eroded away entirely.  A magnetic field would help significantly, but the tidal locking might be problematic for that.

See these recent papers:

https://arxiv.org/abs/1605.01564

https://arxiv.org/abs/1702.06936

I have updated the scenario for my science writing contest:

https://www.researchgate.net/publication/315816995_Trappist-1_Science_Writing_Contest

The changes are:

1.  As per Eric Wolf, the scenario is now about Trappist-1E, not Trappist-1C.  To reflect this new point of view, I have redefined the time unit of one "month" to be the time it takes for Trappist-1D to lap Trappist-1E.  The two predictions I made in March for planets past Trappist-1G remain the same: 14.89859 and 18.76576 Earth days.

2.  As per Adrien Coffinet, I now acknowledge and link to the paper by Rodrigo Luger, et. al. regarding his observation that Trappist-1H has an orbital period of 18.764 Earth days.  I had previously called the two planets that I predicted in March Trappist-1H and Trappist-1I but, to be in line with conventional terminology, I am calling the one with period 18.764 Earth days Trappist-1H and then one that has not yet been observed with period 14.90 Earth days Trappist-1X.

3.  I have expanded on my description of the weather patterns on a tidally locked planet with (at least) five planets near enough to create tides.  I calculate that B, C, D, F, G have gravitational pulls on E that are about 1.5, 4.4, 4.8, 4.5, 2.5 time that of the moon on Earth.  This makes for quite a bit of water sloshing back and forth across the terminal line.  I link to a popular essay about the iron-sulfur world theory.  If there is anybody here at RG studying this, I would greatly appreciate your commentary.

4.  I have added two new discussion questions for students to consider:

First, they are to imagine that they are astronomers there that are viewing our solar system in their telescopes.  They can see Jupiter and its four Galilean moon.  They compare the Jovian system to their own.  In particular, they note that C's gravitational pull on B is over 28 times that of Europa's gravitational pull on Io.

Second, they are to imagine that they are naturalists studying the greenhouse effect on their planet.  Because there are no carbon deposits (e.g. our fossil fuels), their volcanos pruduce little CO2.  The SO2 and ash reflect light back into space and so the volcanos mostly cool the planet, unlike ours, which contribute to global warming.  Lava melts ice, which is reflective, so that would lower the albedo and result in warming, but Trappist-1E does not have any ice on the sunny side of the planet anyway.

I very much appreciate that all of you have taken the time to read my writing contest scenario.  I hope you and your colleagues will find the time to read my revised scenario and comment on it.

Article Trappist-1 Science Writing Contest

Thank you for your informed opinion.

Have you or any one else here at RG attempted to quantify how much energy is contributed by volcanism on the dark side of the Trappist-1 planets?  The SO2 and ash from volcanoes on the sunny side reflects light back into space and probably has a net cooling effect on the surface.  But, if the dark side is covered with water, as I am positing in my scenario, the heat from vents would be conducted throughout the entire ocean.

C's gravitational pull on B is over 28 times that of Europa on Io.  Since Io is the most volcanically active body in our solar system, it seems like the dark side of B must be practically running in lava from the tidal forces of C.

But my scenario, as per Eric Wolf's advice, is now about E.  I calculate that B, C, D, F, G have gravitational pulls on E that are about 1.5, 4.4, 4.8, 4.5, 2.5 times that of the moon on Earth.  Can you tell me how much heat from hydrothermal vents on the dark side would be produced due to volcanism caused by tidal forces?

Kenneth Towe asks, "The question remains... How could life (conventional) have started there if there is water but no land?"

The iron-sulfur world theory explains this.  I link to an article about this, albeit, one written at the high-school level, which is appropriate since I am sponsoring a contest for high-school students.

Life as we know it includes giant tube worms and other creatures specifically adapted to life around a hydrothermal vent.  Admittedly, we have only known of this since 1977 and observation requires very expensive research submarines.  But "life as we know it" does not have to mean critters walking around on dry ground in an oxygen atmosphere where we can interact with them directly.

Ales Kralj-

You write, "Gravitational energy conversion into heat due to tidal forces also depend on the composition of Trappist-1 worlds. It will mainly depend on elastic/fluidic behaviour ratio."

How does the size of a planet affect this?  For instance, I mentioned earlier that C's gravitational pull on B is over 28 times that of Europa on Io.  But it is also true that Io is much smaller than B (about 1/57 the mass), so gravity is not holding it together as tightly and it seems like it would be less viscous. 

Everything else being equal (composition, age, radioactivity of the core, etc.), is there a way to estimate the viscosity of planets roughly the size of Earth; e.g. the Trappist-1 planets that range from 41% to 138% the mass of Earth?  What about a super Earth like LHS 1140b, which receives only 46% the solar energy of Earth but is 6.6 times as massive?

 GOOD ANSWER  Emina M Karisik

Some questions for the astronomers:

If you were at Trappist-1E with the equipment we have here - the Kepler telescope and, later, the James Webb telescope - what would you be able to see of our solar system?  

Do our planets transit the sun from the Trappist point of view?  If we do, what would you see in Earth's atmosphere that would tell you that there is life here?

Would you know only of the gas giants or would you also know of the inner rocky planets?  Would you know that Jupiter has four large moons?  Would you know that Earth has one?

I want to thank everybody for their interest in my writing contest and their helpful comments.  When the school year begins in the fall, if you are in a position to do so, please inform teachers and students in your country of my contest.

Kenneth-

I understand that you do not believe that there is life on Trappist-1e.  But students are welcome to enter the contest with arguments against the possibility of life.  The point is to get them thinking on the subject, not to be a demagogue and insist that there is or is not life there.  Nobody knows for sure and there are many respected scientists that believe it is a possibility.