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#1 2019-06-11 10:49:29

Void
Member
Registered: 2011-12-29
Posts: 2,975

Extrasolar Habitable Planets

This article has slightly annoyed me a bit and prompted some thinking.  Maybe good thinking, maybe bad.
https://phys.org/news/2019-06-narrows-a … verse.html

Their wording, and the limits they impose make them sort of right, but I am not so sure.  I will first refute them a bit.
They stress Hemoglobin in animals, and presume a CO2 rich atmosphere for the worlds modeled.  However I investigated and it seems that while many animals have red hemoglobin, Octopus and Squid have blue.  They are both apparently hemoglobin proteins.  So, for them their argument may hold rather solid.  However some Antarctic fish it seems have clear blood without any Oxygen carrying proteins.  At those temperatures of water, it seems Oxygen levels are sufficient without them.  So, just maybe in some circumstances, animal life would do OK with high levels of CO, and with Oxygen present.  In fact they might breath their energy, but be animated, to seek nutrients on such worlds.
But I can leave that behind.  I am now thinking about the possibility of further out worlds where the dominant gasses in atmospheres by far would be Nitrogen and Argon.  And what I am thinking is that this situation where the atmospheres are more substantial in mass, mitigate many problems for Mars+ sized and Earth sized worlds, perhaps for Super Earths as well.




Then however I was prompted to think about habitable worlds outside of the so called habitable zone, which is really what I care about.
Nitrogen would be critical for worlds outside the so called habitable zone, but Argon could be summoned as an assistant as well.

I think you would need lots of Nitrogen, at least as much as Earth, and going up to perhaps 9 times as much as an approximate limit of options.

Having more Nitrogen is not ruled out in my opinion.  Venus has much more Nitrogen than Earth but is a smaller planet.  Titan has a lot of Nitrogen.   The ingredients that go into a star systems formation could be rather variable I suspect.  Certainly Trappist-1 planets appear in general to have much more water, or that is the current interpretation of data.

I would like to use a few imaginary worlds to try to illustrate what I think.  I can agree with most people that Mars comes short of mass.  So my first example would be an imaginary world, which could be called M+ which would be a world where at the current Mars orbit, gravitation would be sufficient to prevent most loss of Nitrogen by solar heating.

The next example would be E, which would represent an Earth sized planet.

And then to widen the spectrum we could have a SE, which I would specify as having twice the gravity of Earth.  I am not deeply interested in SE worlds at this time, but I want to have something on either side of the Earth's gravitation.

……

I will divert for a bit for my memories of fun facts (Or outdated assumptions?).

I recall that it has been some time ago supposed that worlds could be "Habitable" with up to 10 bars of atmosphere, presuming Earth as the selected example type of planet.  The reason it limits out at 10 is with that much atmosphere, there would be so many clouds and fogs, that sunlight would have a very hard time getting through.  It's albedo would be the limiting factor for getting sunlight to the surface, I guess.

The next recalled idea is that even if you had the present atmosphere of Earth, and could move Earth out to the orbit of Mars, it would still be able to manage some open water ocean.  If you increased the pressure to 2 bar, it would be overall the thermal equivalent of Earth at Mars orbit, that we now have at Earth orbit.

And we have strong suggestions now that even the Mars of reality, did have much better conditions for about 1/2 billion years at the start, and apparently even gushing rivers as lately as 1 billion years.  But as I have said I want to model a M+, where the three methods of atmospheric loss to space would be inhibited.  They are solar wind, Oxygen levitation, and just plain molecule excitation by solar heat.

Such a world even now, if replacing Mars, might be wet, if the atmosphere were of significant volume, and this might inhibit Oxygen levitation.  And I already specified that it would be of sufficient gravitation to inhibit loss of Oxygen, Nitrogen, and Argon by thermal processes.  If you don't maintain a magnetosphere, however many feel that the solar wind will strip off the atmosphere.  This is said to be true especially if the star at the center of the solar system was a M star or Red Dwarf.

However many of the Trappist-1 planets are currently supposed to have atmospheres and in some cases maybe very thick atmospheres, and lots of water is supposed for many of them.  Venus is another example, where I wonder why it's atmosphere was not stripped away by now?  But it has not been yet.  It is said to loose Oxygen however by a combination of electric levitation, solar wind, and I suppose a lesser gravitation. 

I do not know if Mars has a substantial amount of electric levitation.  I have not seen it reported.  Earth does, but at a much lesser amount than Venus.  I suppose it would be possible that the Earth would still loose Oxygen without a magnetic field.  I don't know.  But the rate would be less than that of Venus, because of greater gravitation, distance from the sun, and a much lesser amount of electric levitation of Oxygen.  And all of those are going to be important in my arguments along with other factors.

The critical factor in the magnitude of a Oxygen levitating field apparently is the dryness of a planet's atmosphere.  Or that is what is currently said.  Venus is described as having a very dry atmosphere.  Mars is also dry, so a query about Oxygen levitation for it.  It may also be that in the past when it had a more substantial atmosphere, but became more dry it would have had a greater amount of electric levitation working to make it loose atmosphere.

……


So, I gave speculative world models M+, E, and SE.  And so, what if we could find ones where the atmosphere dominantly Nitrogen and Argon (But not necessarily excluding Oxygen), were values of 4 bar and 8 bar?  (We can even try 10 bar).

We might say they are M+(4), M+(8), M+(10), E(4), E(8), E(10), SE(4), SE(8), SE(10).

We can speculate on where they should be to have .5 the amount of sunlight as the Earth has.  We could model this for a M, K, G, or even bigger stars.

.5 is approximately the number for a E planet which just manages to have some open ocean at approximately the orbit of Mars.

I presume these would be at the outer edge of current statements for habitable zones for any type of star.  (Habitable by possible warming).  For these models I am not going to meddle with atmospheric greenhouse gasses, which would confuse things even more.
I am presuming ~the same as the Earth now.

So, I presume you would test a M+, E, and SE with a 1 bar mix of Nitrogen, Argon, and Oxygen.  M+(1), E(1), and SE(1), at .5 heating from their stars.


But what if you did an M+(2), E(2), or SE(2).  As stated before, at .5 warming, they would be somewhat similar to Earth, but their would be a greater amount of potential to redistribute heat from hot and cold spots.  This will be of even greater importance as you go up in atmospheric pressure.

I am guessing you could move your M+(2), E(2), or SE(2) worlds out to .25 heating, which I think is in this solar system about the inner asteroid belt.

If this held true, then M+(2), E(2), or SE(2) worlds need about .125 heating, somewhere in the middle of the asteroid belt, I suppose.

For M+(4), E(4), or SE(4)> it continues, presuming that the limit of clouds and fogs at  M+(10), E(10), or SE(10) is true.

If I processed all the possible examples, it would be an impossibly long post.

I am going to look at an M+(8) world around a M, K, and G star.  I choose this because I am guessing that this one could be a potential source of a space faring intelligent species.

Around a M star, this word has some advantages.  It's thick atmosphere will help to shield from harmful radiations.  However prospects for photosynthesis are very diminished I think.  It would more rely on chemosynthesis, which could involve CO and O2, and the avoidance of hemoglobin that gets clogged by CO.  I speculate that Kinetic Energy might also work on these, as long as other life forms that have their base in photosynthesis and chemosynthesis did not overwhelm them.  Think poplar tree.  I believe it's leaves shimmy to cool them off, but if you added piezo electric methods, then you have something that might work.

There would be several advantages to a M+(8) world.  I have already mentioned radiation protection.  Also though the problem of axis tilting-shifting, is mitigated because you have a 8 bar atmosphere to re-distribute heat.  If it somehow is a tidal locked world at that distance, the same is true.  As for air currents, if the planet has weather patterns of a kind, I would expect that there would be some places that were excessively windy, but some where wind is more friendly.  If you had "Birds" I would expect that they would use a lot of gliding on updrafts, if such existed.  An 8 bar atmosphere which included Oxygen and such winds would be rather favorable to such an animal I think.  So, the need for a Moon is also a factor you can perhaps cross off, unless it is necessary for the emergence of life.  You don't care nearly as much if the axis shifts, because in general this does not cause as much harm as it would for a 1 bar world.  Another factor for a M+ world is it is smaller, so the distance from cold and hot spots is much less.  Easier to moderate.

What if such a world had a Olympus Mons?  Well, that would allow an intelligent species to acclimate to lower pressures perhaps.  I am thinking of a space fairing species emerging to space.  It would be a step in that direction.  It would also force them to leave their nursery, and cope with conditions of cold, which is also useful in space travel.

And with a gravitation greater than Mars but considerably less than Earth, launching to space would be easier to attain the abilities of.

If you then switch the star to a K or G, photosynthesis becomes much more attainable, life as we understand it more likely.

The cycling of Carbon and Nitrogen will be something to ponder.

For Nitrogen, I presume that if indeed you have sufficient Nitrogen and Argon for such an atmosphere, the incorporation of Nitrogen into sediments will be limited by ice ages.  Less precipitation less rivers.  On the other hand if too much Nitrogen is emitted by volcano's, then more precipitation, and more rivers, and more sediments.  For CO2, I speculate similar.  But in an ice age, it is possible that CO2 could be also immobilized by precipitating onto ice caps.  So, in my mind at least there could be a balancing act that works.

I guess that is enough.

Done.

Last edited by Void (2019-06-11 12:04:18)


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#2 2019-06-11 11:36:32

GW Johnson
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From: McGregor, Texas USA
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Re: Extrasolar Habitable Planets

My understanding of the "Goldilocks zone" calculation is that it is an oversimplified heat balance.  It presumes the blanket effect (greenhouse effect) of an atmosphere similar to ours.  Radiation from the star is balanced by re-radiation from the warmed surface of the planet,  at some less-than-unity IR transmissibility of the atmosphere,  and some near-unity emissivity of the surface. 

Change those assumptions (even slightly) and you get wildly different answers for the equilibrium surface temperature. That's just the math of it,  and real life is always more complicated than some equation.  So,  I wouldn't put a lot of stock in that Goldilocks zone estimation.  We have found places far outside our own sun's Goldilocks zone that seem likely-enough as possible abodes of life.  Such as Enceladus.  And maybe a couple of others. 

One thing that you have to keep in mind is that here on Earth,  we had single-celled life for about 3 billion years,  and under wildly-varying conditions at which only single-cell microbes can survive,  as near as we know.  It's only in about the last 600-million years or thereabouts,  that Earth had both sufficient oxygen in its air and water,  and clement-enough temperatures,  to support multi-cellular plant and animal life as we know it. 

We don't know,  of course,  but it would seem appropriate on the face of it,  to assume something similar would happen elsewhere. 

GW

Last edited by GW Johnson (2019-06-11 11:39:32)


GW Johnson
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#3 2019-06-11 12:05:28

Void
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Re: Extrasolar Habitable Planets

I agree of course.

Done.


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#4 2019-06-11 16:26:32

SpaceNut
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Re: Extrasolar Habitable Planets

We have what we think is ours but in reality if its going to need teraforming then its not in the sweet spot. With that said Venus and Mars are not quite in that zone as we must alter current state to make them inhabitable.

The exo planets that we are find few are inhabitable and fewer are in the zone which due to size of the planets make them not so good for man.

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#5 2019-06-11 18:26:30

Void
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Re: Extrasolar Habitable Planets

Spacenut said:

We have what we think is ours but in reality if its going to need teraforming then its not in the sweet spot. With that said Venus and Mars are not quite in that zone as we must alter current state to make them inhabitable.
The exo planets that we are find few are inhabitable and fewer are in the zone which due to size of the planets make them not so good for man.

Well, that is reasonably true, but there is some talking to do on it....The planets I suggested might exist, are for the most part not detectable by us at this point.  We can detect some candidates.  Proxima Centauri-b, and the seven detected Trappist-1 planets for the most part as far as I know, have chances.  And it is reasonable that many will not qualify for the types of situations I have suggested.

We can detect Proxima Centauri-b, but if there was a "They" there, and they had just the same technology as we do, at the same level, they most likely cannot detect planet Earth yet.  And by my previous post I would qualify Earth as a E(1) planet, around a G star.  There planet is thought to be a E-SE(?) around a M type star.  That is why we can detect it.  They are both in a (1 bar for Nitrogen/Argon/Oxygen) habitable situation, but we do not know if that is the nature of that planets atmosphere.

We are just at the point where we can detect E and SE planets in the classical habitable zone of M type stars.  I don't know what has been found yet that is further out than ~40 light years (Proxima Centauri).

~M+ type planets or at least one has been found but it is a scorcher, as the reason it could be found was it is close to it's star.

So, there are likely many M+, E, and maybe SE planets which orbit a M star that cannot or have not been found, but are in the classical habitable zone.  I have proposed how the habitable zone can be moved much further out, and those will be even harder to detect.

……

The cases of Mars and Venus are interesting.  They have one thing in common.  They both have CO2 dominated atmospheres, with Nitrogen and other gasses in a minority position.

So, they will not behave like an Earth like planet wherever they are positioned.

My understanding is that until the sun gets too hot for it, the Earth will maintain a negative feedback situation.  Liquid water is the setpoint for control.  Some hunting between warmer and cooler times occurs, but it is likely that some open water exists even in the dreaded "Snowball Earth" notion. (I will not deviate further to explain that at this time).  The other thing that could shut this down apparently would be the serious reduction in the rate of Volcanism.  I don't expect that any time soon for Earth.  The process is the Earth cools down.  There is less precipitation.  Therefore less erosion.  Therefore less CO2 and N2 get locked up into sedimentary rocks.  If Volcanism continues, then CO2, and perhaps even Nitrogen builds up in the atmosphere and warms the Earth.  It likely overshoots a bit, and the process reverses.  More rivers, more erosion.  More erosion, more sediments, more capture of CO2 and N2 to the sediments.

A negative feedback situation, until either the sun warms up too much or volcanism dies down.

What I have said in previous posts, is that there well could be similar worlds out there and they actually could have atmospheric pressures from 1-10 bars.  I can amend that and suppose that there might even be a few that are >1 bar, and yet have Nitrogen dominated atmospheres.  That is a possibility, maybe.

Mars almost resembles such, except it is a CO2 dominated atmosphere.  Too little information exists on how Mars works.  It is very suspicious that it appears that it is at a set point of ~5.5 mb, which is just below the triple point of water, as the median surface atmospheric pressure.  We strongly suspect that volcanism may still exist, but it is not very vigorous now.  As I have said, Mars is in another bag, and I think we have serious things to learn about it.

As for Venus, we think the sun warmed up too much for it, and it escaped control.  Ceased to obey the natural controls.

……

Going outside the solar system again, I think it is apparent that different solar systems were not formed from the same "Cake Mix", and the sequence of formation was also likely different.  This could lead to some planets that have insufficient Nitrogen and Argon to resemble Earth, and some that have plenty.  So, if you had a M(1-10), E(1-10), or SE(1-10) world, it may or may not have sufficient Nitrogen and Argon to cause a melt of water.  But if it did, then rivers would form in proportion to the need to sequester some of the gasses, and a negative feedback situation would be established, and would likely be maintained for a long period of time, until the planet got too much heat from its star, or its volcanism was insufficient to maintain it's end of the balancing act.

A fortunate thing for many planets which were in balance, if they are near the edge of the habitable zone, or in a (10) position, is they would be far less likely to go the route of Venus, since the stars will have a much harder time heating up so much as to cause that.  For instance an E(10) planet if it gradually warmed up, would simply drop down to an E(8), E(4), E(2), and E(1) sequentially, as more water flowed.  This presumes that it is not a water world, I am not sure if this can work for a water world, and that it's volcanism is sufficient.

If the idea of Venus having been habitable in the past is true, and since it has significant Nitrogen, it is possible that it was an ~E(2), then and ~E(1), and then maybe an ~E(.5) world, before it became impossible for rivers to run on it.

…..

Mars is really a curious situation.  The pressure now suggests that it is holding a set point at near the triple point of water.  Of course as I have already said, it does not have a Nitrogen dominated atmosphere.  So at least now, it is a different animal.  I also does not currently have rivers running on it.  But it does look like Volcanism is no longer up to it's end of the deal either.

There has been speculation that there may be a precipitation process beneath the soil.  If so, I don't understand how it works.  There are only hints, and confusions.  One possibility is that moisture absorbed in salts, might squeeze water out when made colder.  And that could fill salty aquifers.  Now I see a possibility....while the majority of the aquifer might be rather salty, it is possible that somehow a less salty portion is generated and floats to the top of the aquifer, and freezes.  This would cap off the aquifer from evaporating water to the surface.  If the atmospheric pressure dropped over time, then some moisture would sublimate up to the atmosphere.  There in the atmosphere, losses to space might be primarily Oxygen.  Perhaps the Carbon is harder to loose.  So then the water vapor added to the surface process would be split, the Hydrogen would rather promptly leave Mars, but the produced Oxygen might bind to the CO that is present, to re-form the CO2 that was split previously.  I am not sure how satisfied I am with that notion.  It has possibilities to investigate, but since it is likely that there will be people on Mars, perhaps I will live to see the notion, confirmed in part with modifications, or replaced with something else.





Done

Last edited by Void (2019-06-11 19:18:00)


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#6 2019-06-19 18:04:13

Void
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Registered: 2011-12-29
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Re: Extrasolar Habitable Planets

Since things are so quiet....Too quiet.....

https://www.livescience.com/65743-black … -life.html
Quote:

Voracious Black Holes Could Feed Alien Life on Rogue Worlds
By Mara Johnson-Groh, Live Science Contributor | June 19, 2019 07:11am ET

Black holes are engines of destruction on a cosmic scale, but they may also be the bringers of life. New research on supermassive black holes suggests that the radiation they emit during feeding frenzies can create biomolecular building blocks and even power photosynthesis.
The upshot? Far more worlds roaming the Milky Way and beyond could be suitable to life, the researchers speculated.
For their new study, published May 24 in the Astrophysical Journal, scientists created computer models to look at the radiating disks of gas and dust called active galactic nuclei, or AGN, that swirl around supermassive black holes. Some of the brightest objects in the universe, AGN form as a black hole's gravity binds matter. As that matter swirls around a black hole, it releases incredible amounts of light and radiation. [9 Ideas About Black Holes That Will Blow Your Mind]


Since the early 1980s, scientists have suspected that this radiation would create a dead zone around an AGN. Some researchers even proposed that such an AGN could explain why we haven't seen any complex extraterrestrial life towards the center of the Milky Way. Our galaxy has a monstrous black hole at its center, called Sagittarius A*. Previous studies have found that within 3,200 light-years of a Sagittarius A*-sized AGN, X-rays and ultraviolet light could strip the atmospheres from Earth-like planets. (The Milky Way is nearly 53,000 light-years across.)
"People have mostly been talking about the detrimental effects [of black holes]," Manasvi Lingam, lead author on the study and an astronomer at Harvard University, told Live Science. "We wanted to reexamine how detrimental [the radiation] is … and ask ourselves if there were any positives."
The researchers' models suggest that worlds with atmospheres that are thicker than Earth's or those far enough away from an AGN to retain their atmospheres might still stand a chance of hosting life. At certain distances, there exists a galactic Goldilocks zone that gets just the right amount of ultraviolet radiation.
At this level of radiation, the atmosphere wouldn't be stripped away, but the radiation could break apart molecules, creating compounds that are necessary for building proteins, lipids and DNA — the cornerstones to life, at least as we know it. For a black hole the size of Sagittarius A*, the Goldilocks region would extend approximately 140 light-years from the black hole's center, where 1 light-year is 93 million miles (150 million kilometers).
The scientists also looked at the effects of the radiation on photosynthesis, the process by which most plants utilize the sun's energy to create sugars. And AGN emit enormous amounts of that key ingredient — light. This would be particularly important for plants on free-floating planets, which have no nearby host star to provide a light source. Astronomers have estimated there could be around 1 billion such rogue planets drifting in the Goldilocks zone of a Milky Way-like galaxy, according to Manasvi.
Calculating the area over which AGN could power photosynthesis, the scientists found that large portions of galaxies, particularly those with supermassive black holes, could have AGN-powered photosynthesis. For a galaxy similar to our own, this region would extend around 1,100 light-years out from the center of the galaxy. In small, dense galaxies called ultracompact dwarfs, more than half of the galaxy could reside in that photosynthetic zone.
Taking a fresh look at the negative effects of the ultraviolet and X-ray radiation in these zones, the scientists in the new study further found that the adverse consequences of an AGN neighbor have been exaggerated in the past. Bacteria on Earth have created biofilms to protect themselves from ultraviolet rays, and life in ultraviolet-heavy areas could have developed similar techniques.
X-rays and gamma-rays, which AGNs also spew in enormous quantities, are also readily absorbed by Earth-like atmospheres and would likely not have a large influence on life, the researchers said.
The scientists estimated that the damaging effects of AGN radiation likely would end at around 100 light-years out from a Sagittarius A*-size black hole.
"Looking at what we know about Earth, it does suggest that maybe the positive effects seem to be extended over a larger region than the negative effects," Lingam told Live Science. "That was definitely surprising."

In my mind microbes would matter most, and the potential for them causes me to think that indeed there could be a galactic "Panspermia".

I am thinking that the best potential could be for rather wet worlds, perhaps not so much water worlds.  And yet, Super Earths, flattened by their gravity, could be shallow water worlds, and be grudging about loosing their atmospheres.

When the black hole was active, they might melt to open water, and when the black hole was turned off, they would then freeze over, but potentially maintain a small amount of life under ice or in wet regolith beneath an ocean/planetary glaciation.

These could not only be rogue planets, but also worlds well outside of their classical habitable zone, orbiting various kinds of stars.

Europa's, Enceladus types (If they retain their relationship with their parent planet).

And some may just be like Earth orbiting a yellow dwarf, and live off of sunshine for billions of years.  Plenty of time for the travel I think.

Done.

Last edited by Void (2019-06-19 18:27:53)


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#7 2019-06-19 18:23:20

tahanson43206
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Registered: 2018-04-27
Posts: 605

Re: Extrasolar Habitable Planets

For void re #6 ...

Nice Find!  Thanks!

The following is MUCH smaller scale, but you might find it amusing, and perhaps it will inspire one of your visions of possible futures ...

A writer whose work appeared in the latest Analog has an interesting speculation .... a brown dwarf might be able to sustain life, if it has an output low enough to create habitable zones on its surface.   Like your report of the possibility that galactic black holes may have zones where beneficial effects exceed destructive ones, the possibility that brown dwarfs might provide suitable habitat for life is new to me, and quite intriguing.

The author speculates that there may be a considerable number of brown dwarfs with suitable properties, in the galaxy.

(th)

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#8 2019-06-19 19:08:41

Void
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Registered: 2011-12-29
Posts: 2,975

Re: Extrasolar Habitable Planets

Good comment, I feel. (Th),

Venus, apparently levitates is Oxygen into the solar wind, so it is lost.

Spiders on Earth apparently levitate themselves electrically into our atmosphere when conditions are correct for it.

I don't think we know for sure how a brown dwarf acts.  It is reasonable to squeak in a tiny voice of the possibility that strange things could be possible with some or many of them.  They would not all be composed the same, even if they looked similar.

I can speculate that if they have an electric field of significance like Venus, that could help life forms levitate in the atmosphere.  Their origin would be a puzzle as well.  Panspermia from another?  Perhaps electrically levitating life will eventually be discovered for the Venus, Brown Dwarf, and perhaps even some gas giants, ice giants, and mini-Neptune type planets.  (In some cases).

Done.  Nite Nite.


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#9 2019-06-21 18:07:16

SpaceNut
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Registered: 2004-07-22
Posts: 15,118

Re: Extrasolar Habitable Planets

Two Earth-like Planets Discovered Near Teegarden's Star only about 12.5 light-years away from Earth and is one of the smallest known stars.

extrasolar-teegarden-star-two-exo-planets-hg.jpg

"They are only slightly heavier than Earth and are located in the so-called habitable zone, where water can be present in liquid form."

"The CARMENES Search for Exoplanets Around M Dwarfs - Two Temperate Earth-Mass Planet Candidates Around Teegarden's Star"

https://www.uni-goettingen.de/

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#10 2019-06-21 21:13:25

Void
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Posts: 2,975

Re: Extrasolar Habitable Planets

Well it seems to me that in 10-20 years with new detection methods (Telescopes), there should be some clarification as to if such planets do have atmospheres at all.  The one around Proxima Centauri also.

Done.


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#11 2019-06-21 21:15:54

Void
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Re: Extrasolar Habitable Planets

hmmmm…….

https://en.wikipedia.org/wiki/Teegarden%27s_Star
Quote:

Planetary system[edit]
Observations by the ROPS survey in 2010, published in 2012, showed variation in Teegarden's star's radial velocity, though there was insufficient data to make claims of planet detection at that time.[16]
In June 2019, scientists conducting the CARMENES survey at the Calar Alto Observatory announced evidence of two Earth-mass exoplanets orbiting the star within its habitable zone.[12][17]
Both planets are expected to retain a dense atmosphere, and with high likelihood at least one may harbour liquid water.[18]

I wasn't expecting that.  We have been told that virtually all Red Dwarf planets will not have atmospheres, if they are in the classical habitable zone.

Quote:

Properties[edit]
Teegarden's Star is identified as a red dwarf, but with a mass of 0.08[3] times that of the Sun it is just above the upper limit of objects classified as brown dwarfs. The inherent low temperatures of such objects explain why it was not discovered earlier,[14] since it has an apparent magnitude of only 15.1[2] (and an absolute magnitude of 17.22[9]). Like most red and brown dwarfs it emits most of its energy in the infrared spectrum.[15]
The parallax was initially measured as 0.43 ± 0.13 arcseconds. This would have placed its distance at only 7.50 light-years, making Teegarden's Star only the third star system in order of distance from the Sun, ranking between Barnard's Star and Wolf 359.[13] However, even at that time the anomalously low luminosity (the absolute magnitude would have been 18.5) and high uncertainty in the parallax suggested that it was in fact somewhat farther away, still one of the Sun's nearest neighbors but not nearly as high in the ranking in order of distance. A more accurate parallax measurement of 0.2593 arcseconds was made by George Gatewood in 2009, yielding the now accepted distance of 12.578 light-years.[8]

So, an extremely long lived star, and pretty much infrared.  They don't seem to say much about flares.  Actually those might benefit life, as they might do photolysis in the atmosphere to make chemicals for life to live on.

I am not sure humans will ever get to another star system, but really if you wanted to set up shop for the very long term, this would be some kind of a possibility.

Done

Last edited by Void (2019-06-21 21:22:49)


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#12 2019-06-23 16:16:06

Void
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Registered: 2011-12-29
Posts: 2,975

Re: Extrasolar Habitable Planets

I have been thinking about all the relatively near ~Earth sized planets in the classical habitable zone that have been indicated.

Many sources still say this and that about probably lack of atmosphere, and probable lack of water.  They might prove true in many cases.  I just don't know.  However it seems that at least 6 of the Trappist-1 planets have currently been identified as having lots of water.  Perhaps too much water.  And if water, it becomes hard to see why not an atmosphere.

So, I am going to use them for models, based on the little that is known.  I have a liking for them as well, as they are likely tidal locked.  But I am also going to model them if some of them are not tidal locked.

I have done things like this before.  Hope I don't bore you.  I am going to present optimistic interpretations of what might be possible, but I agree that they may have too much water in many cases.  But I already agreed that some red dwarfs may be dry.  But what about goldilocks?  Just right.  I am guessing that goldilocks happens in that way as well.  While I am modeling the Trappist-1 planets, I am thinking of the whole ocean of possible planets around other stars.  Red Dwarfs, Orange Dwarfs, and perhaps Yellow Dwarfs.

https://en.wikipedia.org/wiki/TRAPPIST-1

It seems that the inner planets stand a low chance of ice that is familiar to us, so I will set them aside, because I am to a large degree interested in ice for this presumed water bound planets.  I will make a note that unlike Venus, it may be that the may not have a strong electric field that can levitate Oxygen off from them to be swept away by a solar wind.  I presume this because unlike Venus, I presume that they are wet.  Venus is said to have a strong electric field because it is so dry.

Something about the atmospheres:
https://aasnova.org/2019/02/22/a-hazy-d … rappist-1/
It looks like g may have a Hydrogen rich atmosphere.
Quote:

Future Answers
So what do Moran and collaborators find? We still don’t know exactly what the atmospheres of the TRAPPIST planets look like, but the authors’ limits suggest that planets d, e, and f could have volatile-rich atmospheres that didn’t form at the same time as the planet. For TRAPPIST-1 g, we can’t yet rule out the spherical-cow picture of a clear hydrogen-rich atmosphere.
This isn’t the end of the story though: the authors show that increased-precision observations will help break many degeneracies in their models. As soon as JWST is on the job, we can hope for more answers!

So, as I am really just using d, e, f, and g as possible general models, I will go ahead and presume the potential of deep ice on their surfaces.

And then I am going to get into materials displacements.  Water, CO2, Methane, maybe others.

I am going to presume that in fact they may have a form of hot ice at the bottoms of deep oceans.  This is generally seen as prohibitive to life.  I will "Try" to argue around that a bit.

And I am going to presume liquid oceans above that ice, and possibly a planetwide floating glacier.  Still due to displacement of ice, I suppose I think some possibility of habitation is possible.

And since there is so much we don't know, there are good chances that what I speculate will come to woe in the future for these specific objects, but as I have said, I am just using them for scaffolds for a model that in some cases will work for worlds something like them.  It's a whole universe of such worlds potentially, possibly.

I will start with g, because it is a big challenge to produce a water wet surface area.  If it is indeed too cold, then I can try to fall inwards sequentially f, e, and d.  No big deal.  I guess it is up in the air as to what it's atmosphere is like.  I am going to presume the existence of Nitrogen, some amount of water vapors, some amount of CO2, Argon I suppose.  Maybe Hydrogen bearing substances or not.

Photolysis may also contribute Oxygen and Carbon Monoxide, but they would be incompatible with Hydrogen fuel type materials.  I am guessing that they would come from broken CO2, and maybe water vapor, although g is expected to be cold.

I am going to list the probable energy sources to melt a subsurface ocean as light sourced from Trappist-1, possible tidal forces, and magnetic induction from the stellar wind from Trappist-1.

I expect due to displacement of surface ice by sublimation and normal evaporation, that a planet wide very thick floating glacier is in a state of continual deformation.  If you started with a uniform glacier floating on water, the sunward side has the potential to evaporate/sublimate, creating a large somewhat sun centered pit.  The evaporated ice to be re-distributed to the colder areas at a higher altitude, and if necessary to the dark side.

I suppose we don't know the thickness of the ice.  I will therefore nominate a model of Europa, for lack of any other knowledge in the matter.  It could certainly be thinner or thicker.

I have seen thinner notions, but not knowing, I will go with 20-30 km in this article.
https://astrobiology.nasa.gov/news/thro … er-of-ice/
So, 12.4274238-18.6411358 miles.  (Sorry rest of the world, am an outdated American, who only partially uses the Metric System.  I feel more comfortable with miles, because it is what I see when I drive a car).

So, I will sort of average that, and say ~15.5 miles, ~24.944832 km.

So, I am presuming that g, f, e, or d (Whichever favors me the most), will have two forces acting against each other for the floating planetary glacier.

On the one hand, I am digging a big hole in the ice on the sunward side, that as it gets deeper and deeper has more atmosphere above it and presumably becomes warmer, and more capable of sublimation, the melting of water and evaporation.

On the other, I have crushing floating glacier ice that wants to flow in and fill that hole.

So, I guess I expect a balance, and a limit on how deep that hole can get.  Obviously it will be very important, how thick the ice is, and what the gravitation is, and what the various heat energies are.

Frankly, I prefer this world I am imagining to never achieve significant open water to the sea below.  I will explain down the road.

I am looking for a downward addition to the presumed troposphere of the hole on the sunward side of the planet.
https://en.wikipedia.org/wiki/Troposphere
Quote:

The troposphere is the lowest layer of Earth's atmosphere, and is also where nearly all weather conditions take place. It contains approximately 75% of the atmosphere's mass and 99% of the total mass of water vapor and aerosols.[2] The average height of the troposphere is 18 km (11 mi; 59,000 ft) in the tropics, 17 km (11 mi; 56,000 ft) in the middle latitudes, and 6 km (3.7 mi; 20,000 ft) in the polar regions in winter. The total average height of the troposphere is 13 km.
The lowest part of the troposphere, where friction with the Earth's surface influences air flow, is the planetary boundary layer. This layer is typically a few hundred meters to 2 km (1.2 mi; 6,600 ft) deep depending on the landform and time of day. Atop the troposphere is the tropopause, which is the border between the troposphere and stratosphere. The tropopause is an inversion layer, where the air temperature ceases to decrease with height and remains constant through its thickness.[3]
The word troposphere is derived from the Greek tropos (meaning "turn, turn toward, change") and sphere (as in the Earth), reflecting the fact that rotational turbulent mixing plays an important role in the troposphere's structure and behaviour. Most of the phenomena associated with day-to-day weather occur in the troposphere.[3]

I highlighted some of the above, because I guess I am hoping for a hole that is deep enough that winds sweeping in from the dark side might actually just sweep over the air in the hole.  While sometimes it might drop into the hole, it will warm up, as it drops.  Not sure how much shelter is available by this means, but it is also a way to sublimate ice in the hole, if the winds do come down and warm up.  They would be very dry in that event.  But it may be possible that the hole could to some extent avoid the worst of winds that are presumed for a tidal locked planet, and yet the upper atmospheric layers would exchange enough heat from day to night side to avoid the condensation of Nitrogen and Argon and so on.  Not necessarily avoiding the condensation of CO2 on the night side.

Excess CO2 may deposit out on the night side, eliminating it to a great extent from the atmosphere.  Could the amount be sufficient to sink the ice on the night side?  Well, chances are determined by amount.  In the beginning of the formation of this system, then it might happen.  If it did sink, then the hole on the night side that it created would scab over with new ice rather quickly I expect.  Meanwhile there are good chances that the CO2 would end up in solution in the ocean that it fell into.  There it might stay, saving for any eruptive features to return it to atmosphere.

So, presuming there is a hole on the day side possible by the means I have speculated on, would it be without nutrients.  I will try to argue that it could be presented with methods for nutrients. Meteorites.  In Antarctica, they often are found on the ice.  It seems like they should sink, but I believe that in some cases, they emerge from evaporating ice, or just stay there.

For this planet wide glacier, I anticipate the pinch to fill the hole will carry them from all parts of the glacier to emerge to the surface.  It is likely that the glacier pinch will not only close in from the sides, but as it thickens the ice under the hole, it will flow up.  The relative heat in the hole will then remove part of the up-glaciation, by evaporation, and displacement to the colder parts of the planets surface, leaving the dust and rocks behind on the surface of the hole.  This could go on for billions of years actually, if the planet behaved in the same way continually.  I suppose it could become too much of a layer, and the hole's ice would be not able to support it.  That would be a bad day for the inhabitants, if any.  But it would reform, after dumping a great deal of the regolith down into the subsurface sea.  For an older solar system, I expect that there would not be a huge accumulating layer of regolith over the holes ice.  And for my purposes, only a little is needed.  Say a few feet or meters (Choose your flavor).  On that, if the air were of a suitable temperature, you could have lichen, bogs, trees, grass.  Probably all the nutrients needed.

I would have had a hard time believing this previously, but I can see that a significant layer of regolith overlies slabs of ice on Mars.  My thinking is that the soil should go under the ice, but it apparently does not.  Perhaps there would be a turnover when sometimes it does go down, but I expect that for the hole, the general process will be ice closing in from the sides, and that pushing ice upwards to try to fill the hole.

A question might be how does the ice form on the night side?  Some, I would think from snows of vapors coming from the hole.  But there could be an altitude barrier, where due to the relative altitude of the night ice sheet, it becomes difficult for vapors to get up that high and cold.  If the hole is deep enough actually there may be a spotty summer cloud area, that typically does not even emerge from the hole.  Snows and rains being internal to the hole to a great extent.  But another method for ice to form would be from below.  After all, mostly that must be true for Europa.  So, the night time ice layer may be very cold, on average, and so I guess as it flows towards the hole it brings "Fossil" cold with it.  And that brings me to another potential method where nutrients might get into the hole.  If it were possible that the sea below had microbes, then they might find the underside of the ice layer everywhere a good place to live.  Of course they need an energy source, and nutrients themselves.  And they might find brine channels in the underside of the ice a good place to live.  And they might die there, and get frozen there, into the ice.  And if the flowing glacier brings them to the underside of the ice in the day side hole, and if that ice tends to upwell, then I expect that that organic matter will end up on the holes floor, as the evaporation process might continue.

This though presumes that there would be an energy source and nutrients in the sea.  Isaac Arthur indicates that this will be very hard for a very deep ocean to achieve.  And I guess he might be right.  And on top of it for some of these worlds, there may be a layer of hot ice covering the ocean floor, if the ocean is deep enough.

Here I will have to grasp at straws quite a lot.  For Jupiter, it appears that a layer of Metallic Hydrogen was expected, and yet it seems that various other items are mixing with it. 

So, maybe this hot ice is not so isolated from the potential of convection.  Perhaps dissolved items in the ice can emerge to the sea floor.  Don't know.

Volcanism?  Well maybe regolith type volcano's can punch through the ice and spew volcanic whatever into the water.  I would think that explosive volcanism would be the best.  But I am willing to be told to sit down and shut up on that.  I just don't know.

But the sea in question is almost sure to have salts, dissolved minerals.  So, perhaps what is needed can be gotten from that for microbes.

But I think the hole on the day side should get enough nutrients from infalling dust and rocks from the sky, it should not need nutrients from below.

…..

For other worlds that do not have seas deep enough for hot ice on the bottom, I anticipate that the problems will be fewer.

For planets that are not tidally locked, a equatorial or polar hole(s) are possible depending on the tilt of the Axis.

So, this is a potential way that the classical habitable zone could be violated, allowing for living worlds, or worlds that could support life to exist outside of the classical habitable zone.

Done

Are we having fun yet? smile

Last edited by Void (2019-06-23 18:00:55)


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#13 2019-06-23 19:12:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,118

Re: Extrasolar Habitable Planets

The dwarf star color represents the temperature that its at currently but does nothing to indicate how hot and much larger it was before its fuel was spent to which during the hotter period the goldilock zone planets would have had there atmospheres blown and burned away....
Billions of year from today even earth surface will be scortched by our sun.

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#14 2019-06-24 19:43:26

Void
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Registered: 2011-12-29
Posts: 2,975

Re: Extrasolar Habitable Planets

Actually Red Dwarf, is in the youth of it's life.  They are very badly behaved magnetically when they are young though.
They can last Trillions of years, unlike our Yellow Dwarf sun.  Eventually they are projected to become "Blue Dwarfs".  But that is a long time from now, as in the age of the universe none have made the transition yet.

That does bring up a fantastical solution to civilizations who's stars are getting on in age.  It is fantastical, you would have to watch Isaac Arthur with the notion of "Star Lifting", this would require a civilization much more advanced than ours, but....

If you could remove materials from the sun, mine the sun, then you might convert it into a Orange Dwarf or "K" star, and extend its lifetime.

Taking it further, if you converted it to a Red Dwarf, "M" star, you would perhaps even make it last trillions of years, into the Blue Dwarf stage.  A bit of a cheat, as it did not start as a Red Dwarf, but had a make-over, then it should act something like a normal Red Dwarf, but the life prolonging may not be as good as trillions of years.

If someone could mine the sun, then mined materials, the tailings, could be dumped onto Jupiter.  The metals used elsewise.  You might even convert Jupiter into another Red Dwarf, but truthfully Jupiter would be a small fraction of the new star.  Also a new star might flair, not a good thing in general, but it would be ~5.5 A.U. from us in the worst case.  Maybe if we were that powerful, we would do Neptune instead.

hmmm....Saturn, Titan.  But a flair star would strip Titans atmosphere off.  But if it was a minimal Red Dwarf, maybe Titan could hold onto its atmosphere.  The trick would be to not build that star to spin.  Still, Titan just barely keeps it's atmosphere now.  Back to the drawing board...…

Maybe we Dyson Sphere the manufactured Red Dwarf?  (Silly Yes!!! smile).

Yes though, fantastical.

Done.

Last edited by Void (2019-06-24 19:47:46)


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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