Earth Like planet around Proxima Centauri?

Void · 2016-08-16 12:40:18

https://nworeport.me/2016/08/16/earth-l … iscovered/

I couldn't resist, I was going to wait for someone else to post about this, but I've done it myself.

Since I have, I will mention that if true, it will certainly be an awesome discovery.

The nearest star system, a mass similar to Earth I presume, a flare type "M" dwarf star, and most likely tidal locked I would think.

I am hoping that there will be more planets in the system, but I believe from what I have read, that previous studies have ruled out any gas giants, ice giants, or super Earths.

If I were to dream, I would hope for another terrestrial planet further out, with a synchronous orbital relationship to the possible discovered planet. This would be similar to the Io, Europa, Ganymede setup, where the orbits are synchronized, and Io is volcanic because of it, and Europa, and Ganymede are thought to have oceans.

Proxima Centauri is expected to have a lifetime of 4 trillion years I have read. Unfortunately the discoverers are the same people who said they found a hot Earth around one of Proxima's presumed sibling stars of Alpha-Centauri. I believe that that claimed discovery is strongly in dispute at this time.

What I am interested in is how Earth like planets might develop in such an environment, and I am also as I said hoping that there will be a cold sibling planet surrounded by a Nitrogen dominated atmosphere, and that that planet might have some significant volcanism from tidal stretching. Ideally both planets would be possible to think about eventual human habitation.

And such a nearby system if it has such a planet/planets, would go a long way towards suggesting how habitable "M" star systems can be, and how different.

Last edited by Void (2016-08-16 12:54:38)

RobertDyck · 2016-08-16 14:56:20

I see the announcement has few details. Have to wait for the official announcement, they said the end of this month. But the habitable zone for Proxima would be 3.6 to 14 days, according to Wikipedia.

When I was younger, astronomers speculated why the terrestrial planets of our solar system appears to be an arithmetic progression. If the distance from Mercury to the Sun is counted as one, Mercury=1, Venus=2, Earth=3, Mars=4, Jupiter=13. The trend fails with gas giants. Of course that's rough, it's actually 1, 1.8684, 2.5833, 3.9361, 13.44. They thought they would have to see planets of another star to determine if that's a coincidence or if there's a reason. Then someone realized we have another system nearby: Jupiter's moons. Jupiter and its moons could the thought of as a mini planetary system. Jupiter's moons followed this rule even more closely. When they had a second example, they studied why. It turns gravity of the planets (or moons) tug on each other, a harmonic forms stable orbits. Objects that are closer will tug on each other more strongly, and shorter orbital periods mean they tug more often. That means tighter orbits causes greater synchronization. If this pattern holds, expect planets of Proxima to be more closely synchronized than planets of our solar system, but not as synchronized as Jupiter's moons.

GW Johnson · 2016-08-16 15:45:56

These are nothing but musings and opinions.

It is my opinion that we know a lot less about these exo-planet bodies than is claimed. I base that on the enormous disparity between discovery claims and actual ground truth right here in our own system over the last couple of centuries. That disparity still exists at one level or another today, even though our sensing technologies are vastly improved.

I think we actually know “for sure” very little about the planetary formation and evolution processes, far less than is “advertised”. If we actually knew very much about it, we would understand why our system seems to be the anomaly in its layout (most seem to have "hot jupiters" very close in), and we would understand why there was a 3.5 billion year long stasis in life on Earth at the oceanic-only one-cell stage. The geologists say there was such life on Earth within half a billion years of formation, and the rocks record its sudden explosion into multicelluar diversity only starting about half a billion years ago.

I tend to think the “Goldilocks zone” theory of classifying whether planets could be potentially habitable is very likely a crackpot notion. If it weren’t wrong, there wouldn’t be potentially-habitable oceans under the surfaces of at least two outer planet moons in our own system, way out in the “too cold” zone. To me, it appears that the universe is quite a bit more complex than an oversimplified theory like that. I think science has the very bad habit of inferring far too much, from far too little in the way of direct observations, and I think this habit dates back centuries. We would do better to break it.

I would hazard the guess that when we do understand this planetary formation / evolution stuff well enough, we will also understand how the moon spiraling outward has impacted habitability on Earth, in what amounts to a double planet system. This may have something to do with why Earth retains its atmosphere-saving magnetic field, when Mars did not. But, such understanding must also explain why Venus bucks that trend! And then there’s the “faint young sun” paradox to explain, too. As I said, it’s far more complicated than these little models we use to “explain” things.

The orbital resonances thing seems to be real, as RobertDyck points out. Whether the stability it confers lasts over the life of the system remains to be seen. Our understanding is too limited to conclude anything, but observations to date suggest an awful lot of chaos during planetary system formation and evolution.

All that being said, I think finding exoplanets about small, long-lived red stars bodes very well for there being billions and billions of planets out there in our galaxy. That’s because there’s a whole lot more small red stars out there than there are sunlike G-type stars. Some as-yet unknown fraction of those planets may prove to be habitable, and a lot of them I would guess will be in locations and situations we have not even imagined yet.

Even if it’s only a very tiny fraction that’s habitable, with enough planets out there, there’s got to be a least a few habitable ones fairly close by. One must look at the small red stars, since there’s so very many of them. Finding one or two small bodies around a star only 4 or 5 light years away is quite exciting.

GW

RobertDyck · 2016-08-16 16:51:37

I have seen science shows in which scientists said exoplanets are more weird than they thought. Once again, reality is more strange than any fiction author could imagine. So you're right, Gary.

One mathematician calculated that our solar system has the maximum number of gas giants for a star this size. He calculated that if we had more gas giants, their resonance would kick one of them out. He also calculated that if Neptune moved farther out, then its gravity would "push" trans-Neptunian objects into elliptical and inclined orbits. Then he pointed out Pluto is in exactly that orbit. This implies at least Neptune if not all gas giants started closer in, then spread out into stable orbits. Furthermore, based on the properties of the planets, some scientists suspect Uranus and Neptune formed in the opposite order (orbital positions) as today, then swapped places. Did that happen when a 5th gas giant was ejected?

Jupiter has greatly influenced our solar system. I suspect that formation of the other planets, and their current orbits, were determined to a significant extent by Jupiter. And I don't think it's unusually far out. In fact, Jupiter is said to be 2.5 times the mass of all other planets, moon, asteroids, comets, etc combined. All two-body systems orbit a common gravitational centre. That includes Earth-Sun, but the Sun is so much larger than the Earth that the common gravitational centre is well within the Sun. However, Jupiter is so large that the common gravitational centre is outside the Sun. That means our Sun orbits a point in space, always on the opposite side of that point from Jupiter. How would we calculate the centre of mass? No matter, my point is the Sun-Jupiter system is as much a twin body system as Earth-Moon. So I don't think Jupiter is unusually far out.

SpaceNut · 2016-08-16 17:30:43

http://nssdc.gsfc.nasa.gov/planetary/fa … ratio.html
Gravity would also bea factor as well as density of a planet for its formation and resonance as well.

http://earthsky.org/brightest-stars/alp … right-star

https://www.inverse.com/article/19695-n … a-centauri

The newly discovered exoplanet is orbiting a red dwarf star called Proxima Centauri, which is only about 4.25 lightyears away.

http://www.space.com/33751-earth-like-p … tauri.html

https://carnegiescience.edu/node/2080

From each the are not direct observation but inferred and via spectral shifts and change in brightness.

Void · 2016-08-16 23:20:53

I thought it would be nice to dream of a world. Something like when people thought Venus and Mars would be nicer than the really are.

But in this case, if it turns out there is a planet, if it is not habitable, it would certainly be entertaining to discover it's nature, being in such a strange star system.

I'm pulling for a water world (Almost) like Earth, with just the Plateau of Tibet poking up out of the otherwise planet wide ocean.
Ya, the pseudo Tibet needs to point at the star, if it is a cold planet, or be on the dark side if it is a warm planet. That way I can sun myself on the beach or go stargazing. I don't ask for much.

Last edited by Void (2016-08-16 23:24:38)

RobertDyck · 2016-08-17 09:09:13

More blatherings of our own solar system. I said a mathematician speculated our early solar system had another gas giant, but got ejected. But did it completely escape? Perhaps that's planet 9?

They found another one. Not as big as planet 9 they were hoping for, but larger than Earth.
Another Odd Object Found Beyond Neptune!

After last month's discovery of a large asteroid in our Solar System beyond the orbit of Neptune, now a smaller Trans-Neptunian Object (TNO) with a very eccentric orbit has been discovered. At an orbit with an inclination of 110 degrees from the orbits of the other planets, which swings backwards in its orbit around the Sun, this new object is a mystery that cannot be easily explained.
Designated 2011 KT19 due to its original discovery in 2011, it was lost until this month when scientists realized the object's strange orbit. It could be an asteroid or possibly a large comet The object is 160,000 times fainter than Neptune, which means it could be as small as 124,000 miles / 200,000 kilometers in diameter.

RobertDyck · 2016-08-17 11:09:20

Mystery object in weird orbit beyond Neptune cannot be explained

“I hope everyone has buckled their seatbelts because the outer solar system just got a lot weirder.” That’s what Michele Bannister, an astronomer at Queens University, Belfast tweeted on Monday.
She was referring to the discovery of a TNO or trans-Neptunian object, something which sits beyond Neptune in the outer solar system. This one is 160,000 times fainter than Neptune, which means the icy world could be less than 200 kilometres in diameter. It’s currently above the plane of the solar system and with every passing day, it’s moving upwards – a fact that makes it an oddity.

Oops! There's a big difference between 200km and 200,000km! I checked, I cut-and-paste the quote from the first article, and the article still says that. The reporter at Space Watchtower made a mistake.

Void · 2016-08-17 13:34:11

I won't force anyone to ask me to get off their side, but so far I am in agreement with all that I have discovered in others postings.

I will add to what I think was said and indicate that I don't think that existing theories about how star systems are formed are sufficiently complete. (Let alone the many ways that planets can become a variation of multiple sub-types.

First of all the weird TNO's. Objects with elliptical, retrograde, and inclined orbits, or variations of such. I do listen to the experts, and they have suggestions/theories as to how they got that way, and I am sure that what they say is the case often. However,
the stories told, for the most part do not seem to factor in rogue objects, or the nature of a stellar nursery, or I am not able to understand how they do yet.

First of all, what happens to a stellar nursery that has not yet formed it's first star, when a rogue object enters it? Specifically, can a pre-conception stellar nursery capture such objects? If so the methods of capture might include gravitation, magnetic field drag, and accretion. A combination of these effects and others could cause a rogue object to be captured into an orbit of the stellar nursery, where at least part of the orbit would place it inside the nursery. Over time with each orbit dip the object would dwell deeper and deeper inside the nursery, spiraling through it towards the center of gravitation of the nursery.

If this can be true, then the first formed star(s) in that situation could result from that process, where a captured object would be a point of nucleation of the first star(s).

Those first stars might form disks and planets, ejecting numerous objects during the process. In fact it would not be entirely ejection, because other less mature concentrations of gas/dust would help some of the objects to leave a forming star system, sucking them in. And so first stars would fling out objects into the nursery, perhaps "Conceiving" younger stars, and so the process would continue until the nursery ran out of food to make new stars.

Objects transferred from older siblings to still to be born younger siblings would not necessarily conform the to spin and plane of the spin of the still to be born younger siblings.

So, before a star system ever formed its own "Native" objects, it would adopt objects from older siblings. Those adopted objects would have a fair amount of randomness as to conformity with the spin and plane of the adopting pre-born star.

But over time the local spin would try to make them more conformed.

The further out they were, and especially if they only impinged on the forming disk twice in a orbit, they might not alter orbit or surface character too fast.

So, some retrograde and inclined objects might persist for a long time. Some non-conformist objects would be destroyed by the disk, and some non-conformist objects would be caused to conform and circularize their orbit.

So, could reformed non-conformist objects that had their orbits circularized by dragging through a forming stars, gas/dust cloud, become the seed(s) for planets? Maybe.

If any of this could be found to be true, the variations in formation of planets would be very large, so it will be very hard to know what to expect when planets are actually characterized.

Last edited by Void (2016-08-17 14:03:47)

Void · 2016-08-17 14:05:34

I am also not sure I buy the story of how "Hot" Jupiter worlds happen.

If rogue objects can produce nucleation points for stars, what happens when a knot of gas has two of them in it?

Or if you reject the idea of rogue objects being involved in star formation, what happens if a pre-stellar cloud has a swirl inside of it so the proto nucleus is split into a binary pair?

My guess is that both objects try to become the main recipient of the materials, but one wins out after a while, stifling the growth of the other. The "Other" then becomes a "Hot" Jupiter.

If that were the case then star systems with a "Hot" Jupiter might have better chances of hosting terrestrial planets, and other objects, because the "Hot" Jupiter would not have spiraled in through the planet forming disk.

Maybe the answer is actually "All of the above". Maybe sometimes one way sometimes another.

Last edited by Void (2016-08-17 14:12:59)

Tom Kalbfus · 2016-08-18 08:39:29

Such a planet would lie within the habitable zone of Proxima Centauri, about 0.023–0.054 AU from the star, and would have an orbital period of 3.6–14 days.

https://en.wikipedia.org/wiki/Proxima_Centauri
A planet as warm as Earth of the same size and characteristics could be 0.041 AU from Proxima, which is about 6.2 million kilometers or 3.8 million miles. Proxima is 0.141 times the size of our Sun. Proxima would appear 3.4 times the size of our Sun in the sky of this hypothetical planet, its disk would be 1.82 degrees wide. Humans living on this planet would need to have a flare shelter handy if they live on the lit side of this planet. The orbit period I get using the orbit calculator,
http://orbitsimulator.com/gravity/artic … ator2.html
is 8.8 days.
An interesting question is if we sent humans to this planet, what would they do once they got there? Maybe we could colonize the dark side. If there is plant life on the planet, it would create molecular oxygen, doesn't matter what type of biology it is, or whether it is compatible with humans, just so long as it creates oxygen so that humans could breathe it. Now this planet is likely to be tidally locked, on the dark side there is likely to be an ice cap, and temperatures would be quite cold, but not enough to freeze or liquefy oxygen, if we warmed that air, we could breathe it, we could melt some water ice. A Proxima Power Satellite could provide us with energy, beaming microwaves down to the planet's surface. Conditions would be like Antarctica during the winter or worse!

Void · 2016-08-18 10:42:07

Glad you showed up Tom.

I took a bit of time to do additional reading, and pulled old memories out of my head also.

Your best bet for a good energy source on a tidal locked red dwarf planet with an atmosphere would be wind power, on most parts of the planets surface.

After that geothermal. Particularly if the planet is in resonance with another planet.

After that, other possibilities are hydroelectric power, since without flowing rivers, it has written that such a planet cannot regulate a upper bound for it's atmospheric pressure.

Red Dwarf planets will be interesting, because a typical view is that they will have a hard time even holding an atmosphere. However I have recently read a contradiction, which indicates that due to the slow heating up of a red dwarf star, Terrestrial planets will be wrapped in a thick dense atmosphere of Hydrogen and Helium. (Why that would not then be stripped away by the solar wind, I do not understand).

It appears from the writings currently available, being on the inner edge of the "Habitable" zone of a Red Dwarf would be particularly hazardous, as even the Earths magnetic field would not protect it in that case. But I do ask the question, "If this is so, how does Venus have a very thick atmosphere?".

So, referencing our solar system but in the mind warping it into a red dwarf system, Venus, Earth, Mars, and Ceres, each speculated on as instead, having an Earth like planet in place of the real planets, what might be the results?

The Earth as Venus, would be in presumed great danger of loosing it's atmosphere.

The Earth as Earth, might still be in presumed great danger of loosing it's atmosphere.

The Earth as Mars, would be colder than our Earth, but might be protected well enough by Earths magnetic field. I believe I have read that even at the Mars orbit, Earth would manage to have some open ocean water.

The Earth at the orbit of Ceres (And incidentally outside of the "Habitable" zone), would have a very hard time generating any liquid water under 1 bar atmospheric conditions.

How for the Mars and Ceres situations, it is thought possible that the feedback situation would cause the buildup of additional atmospheric pressure, and at those locations a Earth style magnetic field might be more assured as being sufficient to protect the atmosphere.

Such an atmosphere as I recall could build up to up to 10 bars, before clouds, and dust would begin to cause an "Anti-Greenhouse" effect.

Standard humans would have a hard time dealing with more than 6 bars due to Nitrogen narcosis, probably that is to high, but I am going to presume that atmospheres from 1-4 bars might be OK for standard humans.

Earth at Mars would probably try to regulate to 2 bars, and Earth at Ceres might be hoped to have a pressure of somewhere around 4 bars of atmosphere, presuming a Nitrogen dominated atmosphere.

This might be very nice, as a thicker atmosphere would offer more protection from radiation problems, and more wind power, and interesting aspects for aircraft flight. Such a thicker atmosphere also might distribute heat much better from the day side to the night side, and also protect the night side from the chilling effects of the universe.

On the negative side, a thick fast wind would tend to blow down your buildings, and be a hazard to human health. You might get blown away.

However the further out the orbit, the less likelihood of tidal locking of the planet.

The feedback I have talked about is the incorporation of atmosphere in rock. If a planet is not warm enough for liquid water rivers, then much less of this will happen, therefore the atmospheric pressure is supposed to build up until liquid water rivers occur. The liquid water rivers are supposed to limit any further build up of atmospheric pressure.

Done.

I lied.

Even if such a world existed, and the sunward side were hard to inhabit due to radiation risks, the dark side would be more protected I presume, and you could certainly make it a more happy place with artificial lighting most likely powered by wind power. I have often presumed that in this situation the light would shine in direct proportion to the intensity of the winds, so if you lived on a river, lake, or sea shore and had a farm field, a wind gust would light things, up, and then during a calm everything would go dark and you could see the stars in the sky. Lets imagine that cycle might last minutes. That would be really cool, I think. Of course if you were in a city, there would be constant lighting and light pollution.

But with a denser atmosphere, and ocean circulation, it is possible that the night side might not be too cold, at least not in some parts.

Now I am done. Maybe

Last edited by Void (2016-08-18 11:26:14)

GW Johnson · 2016-08-18 13:19:46

I looked up this same report on space.com. There may be a small, presumably rocky planet orbiting Proxima Centauri, and it may be at a distance that is neither too hot nor too cold, if you believe in the Goldilocks zone model (which I do not). The report on space.com had a lot of weasel-word if's to it. Wasn't any solid fact at all in their report, as a matter of fact.

I could not ferret out the astronomer(s) who might be the ultimate source of this report. Right now, everything points to an article in Der Spiegel, but nobody can verify it. Looks to me like it's about as probable to be a hoax as it is real. Maybe even more likely hoax than real. But we'll see, after a while. I strongly recommend you all watch the scientific journals, not the blog and gossip sites. I don't even trust half of what I see on space.com.

From what I have read and seen in venues that I trust, exo-planet detection up to now has been based on the wiggles in a star's position. The amplitude and period of that wiggle can be measured to some level of accuracy (fairly crude as near as I can tell). If you assume a mass for the star (there's one level of indirect inference right there), then you can estimate the mass of the planet, rather crudely, and you can estimate the distance between them (also rather crudely).

From there, saying that smaller masses are Earthlike and rocky, while bigger masses are gas giants, is absolutely nothing but an unjustified assumption. It doesn't even qualify as an inference from something else. It's based on our solar system, which only has smaller rocky worlds and gas giants, but the configuration of our system matches none of the systems found so far (gas giants close in). Using it as a model on which to base inference is dangerous at best.

There is a second technique based on light-dimming, but it's even less precise. Too new to trust yet, at least not very far.

As for imaging such planets, that technology is as yet completely unready and completely untested. But there is a concept to test, called "starshade". IF it tests as advertised, THEN we might have a way to image such planets where we can isolate what's in their spectra from what's in their star's spectra (something not possible now). THAT would put us to the sort of remote sensing capability we had relative to Mars at the end of the 19th century. (Which wasn't very good in terms of real ground truth.)

If you haven't guessed by now, I put much lower stock in a lot of the journal reports than many of you all (because there's too much inference in lieu of direct observation), and I put virtually zero stock in reports off blog sites and gossip sites (because the lie content I observe at 50-to-100%).

GW

RobertDyck · 2016-08-18 13:38:54

Europe built a space telescope called Kepler. The Kepler space telescope has found thousands of extra-solar planets. It works by light-dimming, so that technique is fairly advanced. They measure a star's brightness, if it dims at a periodic interval, dims a certain percentage and stays that way for a measured time, then returns to full brightness. If that happens it means something passed between the star and the telescope. The percentage of light dimming is interpreted as a percentage of the area of the star that was covered. If the star dims 1%, then the planet must be 1% the cross-section area of the star. They can measure the size of the star's disk, so can calculate the planet's diameter.

If the star's spectra shift red and blue, then that means it's moving. Red shift means it's moving away from the telescope, blue means moving toward. If the colour shift is coordinated with light-dimming, that means the object occluding the star (blocking its light) must be big enough to cause the star to wobble. Colour shift can be more precisely measured with lines in its spectrum. Amount of colour shift can tell astronomers how fast it's moving, not how far. Some cleaver math can give you relative mass.

Lines in the spectra can also be examined as the planet crosses in front of the star. If lines in the spectrum appear during light-dimming that don't appear at full brightness, then that's light passing through the planet's atmosphere. Matching those lines to absorption lines of gasses can tell you the composition of the planet's atmosphere. Of course the planet has to have an atmosphere to do this, and it doesn't work if clouds are completely opaque. And the star has to be close enough to Earth for a sufficient amount of light to reach us. This doesn't work with distant stars.

Light dimming for detection, red-blue shift, or atmosphere analysis only works if the planet crosses the face of the star. If the planet is in an inclined orbit that doesn't pass in front of the star (from our perspective) then none of this works.

::Edit:: To do this Kepler stared at one small patch of sky. It's interesting to note that Kepler has found 2,300 confirmed planets as of January, and 3,601 unconfirmed planet candidates, and 2,165 eclipsing binary stars. (Wikipedia) However the patch of sky is the size of your thumb nail at arms length. This raises the question how many other planets are out there?

Last edited by RobertDyck (2016-08-18 13:43:42)

GW Johnson · 2016-08-18 16:03:53

Well, Kepler is the first big-science project to use the light-dimming technique. It seems to work quite well, Kepler seems to have identified a few thousand exoplanets now. Converting those light-dimming curves and doppler shifts into planet masses and sizes is where I criticize the calculations.

I'd not count on independent measurements of a star's diameter. They can only do that for close stars. Proxima Centauri is definitely close enough; I've a seen a number quoted for the arc its diameter subtends. Most of the systems Kepler identified are too distant for direct measurement of the star's diameter, as far as I can tell.

Also as far as I can tell, for most stars, diameters and masses are inferred from the Hertzsprung-Russell diagram and theories about stellar evolution. That does seem to work fairly well much of the time, but never forget these are inferences, not direct observations. There's a difference.

A thumbnail out of 4 pi steradians of sky says there's an awful lot of planets out there. Even at average only 1 planet per star, the number is 100's of billions of planets for our galaxy. Some tiny fraction of those ought to be "Earthlike", whatever that really means. Some small fraction of those might even be close enough to reach, especially if we get around to inventing a Star Trek-like "warp drive". I'm not going to hold my breath, though.

As for the "Goldilocks zone" theory they use to try to classify these things: as originally proposed, Venus, Earth, and Mars were all in this zone. Venus is very "Earthlike" in terms of rocky composition, mass, and size. Yet Venus is anything but habitable. Mars is more "Earthlike" in its appearance, less so in terms of mass and size. Yet it actually was habitable around 3 billion years ago or so.

They're talking now about potentially life-bearing subsurface oceans on Enceladus and Europa, and maybe some other places, none of which are in the classic Goldilocks zone. The Goldilocks zone calculation itself depends upon an assumed greenhouse effect of an atmosphere about like Earth's. (Without this effect, Earth would freeze solid.) But, Earth's atmosphere (and its greenhouse effect) seem to be unique in our solar system. Plus, our solar system is apparently unique among those exoplanet systems found so far.

And THAT (an inapplicable model for inference) is why I think the Goldilocks zone calculation is more nonsense than sense. (That also affects the so-called "snow line distance" estimate, too.) Too many assumptions, too many inferences, not enough trustable theories.

Just inferring "rocky and Earthlike" off of a small mass estimate is also nonsense, as the Venus-Earth-Mars comparison demonstrates.

What we really need is an operational definition of "habitable", one that allows for degrees of habitability. We can build cities and live on Mars, even though it is no longer "habitable". We can do that on the moon. We could even do that near the poles on Mercury. We could do it on a lot of asteroids.

So, what is "habitable", and just how "habitable" is it? Aye, there's the question! And one that cannot be answered (yet) about any of these exoplanets.

I kind of like the notion of the "starshot" laser sail micro-craft as a means to get some real ground truth. About like what we got from Mariner 4 in 1965 at Mars, which turned out to be not so good, compared to what Mariner 9 and subsequent saw. But the "starshot" micro-craft would be better than any conceivable remote sensing across light years, I should think.

Could the thing do a "grand tour" to two, or even all three, of the stars? No laser, but it'll still have the sail.

GW

Last edited by GW Johnson (2016-08-18 16:18:26)

Tom Kalbfus · 2016-08-18 21:06:06

A swarm of micro sails that can communicate across light years with power beamed across light years is a big assumption! At 20% of the speed of light it would take 21 years plus 4.25 years for the signal to get back to us, and how many pictures would we get? The swarm would be in and out of the Proxima system very quickly as it passes through at 20% of the speed of light.

Void · 2016-08-18 21:17:37

Noting all the very reasonable cautions against optimism for an Earth-Like planet around Proxima Centauri, I think I can turn to a degree of increased optimism for worlds around Red Dwarfs ("M") stars in general.

http://www.skyandtelescope.com/astronom … -01222015/

Do Atmospheres Spin Worlds to Habitability?

By: Shannon Hall | January 22, 2015

New research, however, suggests not all is lost for tightly orbiting planets. Jérémy Leconte (University of Toronto and Pierre Simon Laplace Institute, France) and his colleagues think that an atmosphere’s effect might be strong enough to break any tidal locking, allowing the planet to rotate freely and exhibit a day-night cycle similar to Earth’s.
Leconte and his colleagues created a three-dimensional climate model (similar to those used in analyzing climate change on Earth) to predict the effect of a given planet’s atmosphere on the speed of its rotation.
It all goes back to the amount of starlight able to penetrate the planet’s atmosphere and reach the surface. Any temperature differences at the surface — between day and night and between the equator and the poles — drive winds. Those winds constantly push against the planet by running into mountains or creating waves on the ocean. Such friction then influences the rotation rate of the planet, helping to speed it up or slow it down.
“While gravitational tides and their associated torques tend to tidally lock the planet, thermal tides, produced by the star heating the atmosphere of the planet, tend to oppose the gravitational tides, and prevent the planets from becoming tidally locked,” says coauthor Norm Murray (University of Toronto).
Astronomers have long seen this effect on the planet Venus, where the atmosphere’s influence is so powerful that it forces the planet out of synchronous rotation into a slow retrograde rotation: to a Venusian, the Sun rises in the west and sets in the east. But Venus’s large atmosphere weighs in about 90 times heavier than our own, and planetary scientists didn’t think thinner atmospheres like Earth’s could throw their weight around as effectively.
Leconte’s simulations show that thinner atmospheres actually have a larger rotational effect on their planets. With less scattered sunlight, extra heat reaches the deepest atmospheric layer and creates stronger winds. If Venus were to have an atmosphere like Earth’s, it would spin 10 times faster. This is radically different from previous research, which suggested that it would spin 50 times slower.
An unlocked planet should have strong atmospheric mixing and relatively stable temperatures. “This greatly increases the chances for atmospheric stability — and, hence, for life — on any of these bodies, provided they are Earth-like in terms of mass, water content, and maybe their atmospheres,” says exoplanet expert René Heller (McMaster University, Canada).
In addition, it avoids many problems created on tidally locked planets, Take the cold trap, for example. “Liquid water on the sunny side tends to evaporate, and is thence transported by winds (driven by the temperature gradient) to the dark side, where it precipitates as snow and forms large-scale ice sheets,” says Murray. “Since the back side never sees the light of the host star, the ice sheets may well be permanent.” Eventually all the liquid water would move to the dark side, making life impossible.
Although the researchers show that a large number of known terrestrial exoplanets should have a day-night cycle, potentially rendering them habitable, the duration of their days could last between a few weeks and a few months. So Heller cautions that these planets would still be far from Earth-like, with only a few days per year.
Hopefully the theoretical results don’t remain in the observational dark for too long. Astronomers can determine the temperature of exoplanets when they pass behind their host stars. But it won’t be easy to do this for Earth-size worlds. Leconte thinks it might be within reach of the James Webb Space Telescope (slated to launch in 2018) if there is a particularly favorable planet to observe. If not, astronomers might have to wait for the European Extremely Large Telescope, whose first light is tentatively scheduled for 2024.

Similar articles indicate that Venus rotates because of such an effect. Also, it is said that if Venus had a atmosphere as thin as Earths, it would rotate 10 times as fast as it does.

Rotation helps to provide magnetic field, and magnetic field helps to preserve atmosphere. (This is what I have been told).

So, if so, some planets presumed to be DOA, might not be. And it would also indicate that long periods of rain and snow on the dark side would be followed by melting and drying on the day side.

A land plant that might make it under those conditions might be grass. Even if there were a solar flair killing it's blades, perhaps the root system would remain alive to sprout again.

And if you had grass, perhaps grazing animals could eat it. How they might deal with solar flares, is a question. Perhaps some would only graze in the night time and would seek shelter during the day, like rabbits with a burrow. Perhaps they could graze in the daytime, if they stayed near their burrows, and had finely tuned senses that warned them of flares.

Maybe some animals would be amphibious, and would again only venture far into land to graze in the early hours (Days) of the evening?

Perhaps some amphibious animals would not come to land to feed, but to have young, to protect them from aquatic predators, maybe like a penguin, perhaps they would do that at night.

Perhaps flying birds would tend to be burrowing also. They might also need to be able to sense when a flare was about to occur.

Some plants might only perform reproduction in the nighttime under snow layers?

My understanding is that the spectrum of light from a Red Dwarf is better at melting ice than is ours, so, this variant factor would also affect habitability (Whatever that is).

As for humans, I guess they might have to emulate these imagined animals to make it on such a world.

Last edited by Void (2016-08-18 21:34:51)

RobertDyck · 2016-08-18 21:31:40

Some extrasolar planets have been imaged. Using two telescopes and cancelling light between them. They focus on one star, and by cancelling the light of that star they can see a dim object near it. Such as a planet. The first planet directly imaged was in 2010. All exoplanets imaged so far are gas giants larger than Jupiter, and widely separated from its star.

Actual images of extrasolar planets. Yes, it has false colour. Telescopes can see the entire spectrum, human eyes can only see 3 colours, so which colours do you represent?

The three known planets of the star HR8799, as imaged by the Hale Telescope. The light from the central star was blanked out by a vector vortex coronagraph.

2MASS J044144 is a brown dwarf with a companion about 5–10 times the mass of Jupiter. It is not clear whether this companion object is a sub-brown dwarf or a planet.

Coronagraphic image of AB Pictoris showing a companion (bottom left), which is either a brown dwarf or a massive planet. The data was obtained on 16 March 2003 with NACO on the VLT, using a 1.4 arcsec occulting mask on top of AB Pictoris.

Directly imaged planet, Beta Pictoris b

And Wikipedia has an animated GIF demonstrating light-dimming works, technically known as the Transit method.

Void · 2016-08-24 13:15:30

So, we just got lucky.
http://www.msn.com/en-us/news/world/sci … spartandhp
1.3 times the mass of Earth, so, not too much more gravity? And better chances for a Magnetic field, Atmosphere and Volcanism, and perhaps water, I would think. But, you get a year older every 11 days.

And with a larger than Earth presumed gravitation, shallower wider spread oceans and seas perhaps, if there is water.

I would be still happier if they suggested that it had a companion further out in that stellar system, but it sounds like they kept the suspected information about Proxima b quiet since 2013. So, it wasn't hokey science after all.

Woopie! I was wrong.
Quote:

Proxima b may not be flying solo. "We have some suspicions that there is another signal around the star," Reiners said.

I presume that that signal is weaker, and harder to prove, so it either is a smaller planet further in, or a sizable planet further out or a false positive.

I'm pulling for another terrestrial further out. In fact, since it can't be a gas giant, ice giant, or super Earth (Prior searches have ruled those possibilities out, I believe), it almost has to be of terrestrial mass, because I don't think they could detect object much smaller than Mars anywhere. (But maybe I'm wrong about that).

If it exists, then perhaps a resonance regardless if it is inside or outside the orbit of Proxima b. Of course too much of a good thing that way could have a bad influence for habitabilty, as well as possibly a good influence.

An ideal setup that way could foster a world which could be persistently habitable well through parts of Proxima Centauri's estimated very long lifetime.

Last edited by Void (2016-08-24 13:45:56)

RobertDyck · 2016-08-24 14:28:20

The paper is published. Here is the actual science paper published in the journal Nature...
A terrestrial planet candidate in a temperate orbit around Proxima Centauri

Abstract...

At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (α Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days (ref. 3) and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface.

And an article published by MSN, with a video clip of the actual astronomer giving a presentation to an audience. (posted by Void in another thread)
Scientists find Earth-like planet circling sun's nearest neighbour

The astronomer said:

We have no clue whether this planet has an atmosphere or not. Whether it has water or not. But the existence of it is actually plausible.

Details:

minimum mass 1.3 Earth masses
orbital period 11.2 days
calculated equilibrium temperature for a planet at that distance is within the range where liquid water could exist on its surface

It also said astronomers are continuing to study the data. They suspect another planet.

Last edited by RobertDyck (2016-08-24 14:42:28)

Void · 2016-08-25 17:57:50

I think I have reasoned out how a tidal locked world could retain habitability after the first hazardous stages of it's solar system have passed.

Taken separately, two ideas about tidal locked worlds around red dwarf stars, seem to indicate hazard to the possibility of a biosphere as we know it.
1) The magnetic activity of the young star will severely erode the young planets atmosphere.
2) The tidal locking may cause the atmosphere to collapse on the dark side.

But I think taken together with other factors, it can be a recipe for later success, particularly with the so far described Proxima b.

I am going to start with some presumptions about the newborn Proxima b.
a) It is not tidal locked at first.
b) It's original atmosphere may in part be composed of Hydrogen and Helium. (This is not necessary to my argument, but it is helpful).
c) As newborn, the planet has more internal heat than would be true now.
d) Proxima Centauri although more magnetically active, will be less thermally active (This could be untrue, if it still has heat of condensation, but lets just say the scenario begins when the star first starts up fusion).

So Proxima b is spinning initially, (And this offers better chances earlier for a magnetic field), it has an atmosphere, it is hot inside, but Proxima Centauri is trying to strip its atmosphere, and finally the surface of Proxima b should be cold, both because it is further out in it's habitable zone than Earth, and because the newborn star is not shining as brightly as it is now.

Since the planet is spinning the "Cold Traps" will be at the poles, until the planet becomes tidally locked. Therefore condensable substances from the atmosphere will accumulate in the cold traps. Water for sure, and perhaps CO2, Ammonia, Nitrous Oxide, and other substances.

I expect water vapor to form from contact with Hydrogen in the atmosphere with hot surface materials. And that will largely migrate to the "Cold Traps".

Other than with ground heat, there will be little chances of an ocean or sea. Even if the ground heat melted water, it would likely create ice covered reservoirs. So the atmosphere will be dry, most likely composed of N2, and maybe Hydrogen and Helium. Many substances will be protected from being stripped from the atmosphere by the stars wind because they will be locked in condensates on the surface.

After the planet is tidally locked, the "Cold Trap" will be on the dark side of the planet, and the ice caps should migrate there, for the most part.

Any Hydrogen and Helium will tend to be stripped away preferential by the stars magnetic wind, in part protecting the Nitrogen in the atmosphere (I presume), until the Hydrogen and Helium loose significance in the atmosphere, and then the N2 will begin to be stripped away, if the magnetic field of the planet is not sufficient.

Preservation of Nitrogen for the planet will be harder than the other atmospheric substances. I see ways however. I mentioned Nitrous Oxide, and Ammonia. With a large ultraviolet flux, I see the possibility that these could be synthesized in a cold Nitrogen atmosphere, particularly if some water vapor and Hydrogen were available. They would also not tend to last very long, unless they ended up sequestered in the "Cold Traps".

N2 itself might be able to be condensed on the dark side finally, if the atmosphere were sufficiently eroded away. The ideal scenario would be for a atmospheric component of Hydrogen and Helium to persist long enough for the Nitrogen to condense out.

Finally dust layers, to lock down the deposits in the "Cold Traps".

Mars shows that a cold dry world can have enormous dust effects in it is wind with Aeolian deposits made from that process.

I would anticipate Proxima b to be very windy, even if it is very cold in it's initial stage, and to have lots of dust, including volcanic dust. Some of this should get deposited on the dark side of the planet in layers over the frozen ices.

Even if the whole remainder of atmosphere were then stripped away, this should protect to a degree from the magnetic winds then stripping the materials from the dark side.

The situation would remain stable for the most part then until Proxima Centauri reached a threshold of radiance, and some event triggered a run-away release of the stored materials. Such an event could be an asteroid impact after the stars radiance had reached sufficiency.

The hope would be that by then the magnetic wind would have quieted down sufficiently to be more permissive to an atmosphere.

As it happens, reading I have done seems to indicate that Proxima Centauri is not that much of a threat to an atmosphere now.

Last edited by Void (2016-08-25 18:40:28)

Void · 2016-08-25 18:42:04

The just prior post suggests a possible evolution for Proxima b.

I will now suggest what the resulting world could be like now, if events unfolded something like what I have suggested previously.

Taking a break.

During the period where the atmosphere might have been collapsed, additional materials would probably accumulate to the dark side from active volcanism if it exists.

So, I presume that at some point the atmosphere and a hydrosphere may re-inflate, the cause being an increase in the luminosity of Proxima Centauri, and perhaps an impactor of significance.

Then the planet might overheat, perhaps something like Venus, but perhaps not to the same magnitude. There would likely be rain however, and I presume eventually rivers. (Not sure, maybe it would lock into a Venus even though it is in a much colder location).

The outcome could be dependent on the amount and kind of volatile materials stored on the dark side.

If there were rivers, then there would be sedimentation, and this is supposed to bring the atmospheric pressure down to an equilibrium where the amount of emitted gasses is balanced by sequestering them in sediments. If the sequestering went too far, then less rivers would flow, and less sequestering. So it should find a balance.

If the atmosphere is dominated by a Nitrogen or Nitrogen/Oxygen mix, then the atmospheric pressure of Proxima b should be somewhat higher than ours to provide a sufficient greenhouse effect for rivers to flow.

The amount of water should be important. If a lot, then an ocean that would likely be mostly on the dark side, but would overlap into the day side. In that case a thinner atmosphere might result, as there would be more evaporation to provide rivers.

But if that world had only a small amount of water, then the largest bodies of water should be on the dark side. Usually it seems it is though that such bodies of water might be completely frozen over, but that might not provide sufficient moisture to create rivers, and so the atmospheric pressure would rise, until sufficient evaporation for rivers occurred. And that might lead to open water even on the dark side of the planet.

The day side might be moist under these conditions, only in the upland areas due to the cold provided by higher altitudes.

One exception to that, and a further source of rivers could be wind blown snow. If fine dry snow falls on the dark side, it should be possible for it to be swept to the day side, by wind. Particularly on Proxima b, as especially without a very large ocean, thermal equalization between the day and night sides would primarily be provided by high winds.

Wind swept snow has occurred in Asia on Earth, where snow from Siberia is swept southward by the winds.

Done.

Last edited by Void (2016-08-25 19:05:59)

Tom Kalbfus · 2016-08-26 11:20:11

So there are two scenarios. one where Proxima is largely barren, maybe has microbial life in its oceans, the other is a Proxima with a riot of life on its surface, multicellular plants and animals. What happens if humans try to colonize a planet if the second scenario is realized. Lets say that after a journey of several decades a spaceship sets down amidst a forest? Would native life be useful to human colonists?

Void · 2016-08-26 11:41:07

I think that in many cases invasive life would be at a disadvantage.

Usually invasive species are a problem, because the are distributed to a habitat that is similar to their natural one.

If you put Alligators in the Antarctic ocean, the Penguins and seals win.

Last edited by Void (2016-08-26 11:41:33)

Terraformer · 2016-08-26 11:42:02

That depends. What's it based on? If it's carbon based, breathers oxygen, uses water as it's solvent, uses DNA, RNA, and proteins, and has left hand chirality... then we may be able to eat it, if we can get our immune systems to handle it.

Whatever it is, it would be a source of useful chemicals, even if it's based on an alternative biochemistry. The closer it is to ours, the more useful - we should be able to digest carbohydrates from right-handed chiral organisms, though not proteins. Also, the more dangerous.

If it *was* based on exactly the same biochemistry, that would be evidence for panspermia, especially if the comets in the area have chemicals of right handed chirality.

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