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  #1  
Old 02-22-2017, 04:27 PM
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Default 7 Earth-sized worlds found orbiting star, could hold life

7 Earth-sized worlds found orbiting star, could hold life.

That's cool.

http://abcnews.go.com/Technology/wi...d-life-45662522
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Old 02-23-2017, 06:13 AM
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Yes, but I'd discount any of those planets as life bearing or even terraformable. They orbit so close to the star that they are all probably tidally locked, and Trappist 1 is a young M Class red dwarf which are prone to heavy flare activity.

I'd be more excited if they had found rocky earth size worlds in the habitable zone around a K, G, or F class star.
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Old 02-23-2017, 01:04 PM
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Sounds like the "12 Colonies of Man" from the original (and best) Battlestar Galactica... LOL

It's certainly interesting, but begs a lot of questions...

First off, 7 Earth size planets orbiting a Jupiter size red dwarf inside what in our solar system would be the orbit of Mercury... HOW does a system like that maintain orbital stability for any length of time?? Are we witnessing something transitory or what?? I'd love to see the orbital mechanics of this one... is there some synchronicity or "resonance" in the orbits that keeps it stable?? Some large unseen planet orbiting further out that keeps it stable? What? I'm extremely curious.

Second, the star is Jupiter-sized and essentially at the bottom end of a red dwarf scale, barely above brown dwarf status by the sound of it. Such a star can be EXTREMELY long-lived, because it gives off VERY little heat and light. That low amount of light and heat at the low end of the spectrum means that very little heat/light will be available for photosynthesis... that has some interesting repercussions for life... without solar energy to maintain the food chain (based on photosynthesis here on Earth) higher life (plant, animal, and fungi) would be impossible, at least as we know it, and forming complex ecosystems in such an energy-starved environment would be virtually impossible. We know from Earth examples that simple life based on chemosynthesis and totally isolated from solar energy (either on the deep ocean floor near hydrothermal vents or in deep caves) is possible, but complex ecosystems are pretty much out (unless you count rock shrimp and tube worms feeding around the 'black smokers' on the ocean floor that came from "elsewhere" in the ocean but live in that environment now with the chemosynthetic bacteria.)

Third, the planets in that close of an orbit to the star WILL be tidally locked (unless they "recently" migrated into those orbits and still retain their rotational momentum and haven't lost it yet to tidal braking). This has profound consequences for life as well... One side of the planet will be a parched, burning hot desert in eternal daylight, even under a, by our standards, small, "cool" red star, and the other side of the planet will be a deep frozen wasteland in eternal night. The only "habitable zone" on the planet itself will be the "ring" of territory along the terminator between day and night-- a band perhaps a few thousand miles wide where it's eternal sunset or sunrise, depending on your point of view (at least that's the only habitable zone for photosynthetic plants, which is the basis of the food chain here on Earth, and therefore the likeliest environment for complex ecosystems). Depending on the climate and atmosphere, even this area COULD potentially be very hostile, with hot drying winds forever blowing from the daylit desert across this "habitable twilight zone" into the frozen tundra of the nightside, or vice versa-- bitterly cold winds blowing off the frozen ice cap on the night side across the habitable zone and into the hot daylit desert until the air heated up, rose, and blew as hot air through trade winds back into the cold antipodal frozen nightside and cooled and sank to the surface, much like ocean currents on Earth do. This could make the "habitable ring" quite inhospitable, depending on location and stellar energy output.

Fourth, due to the close orbits, it's almost certain (I would think anyway) that large satellites are out... IOW, no large moons like Earth possesses. IF one of these Earth-size planets had a Moon-size satellite orbiting it at about the same distance as the Earth-Moon system, the satellite would probably be quickly either 1) ripped away from it by gravitational interaction with the other "nearby" planets it passed or was passed by in its close solar orbit, or 2) the Moon would be decelerated by gravitational interaction and either dropped into a lower, closer orbit to the parent planet, or crash into it altogether... which again would have devastating consequences. Many scientists believe that the gravitational influence of the Moon is VERY essential to life here on Earth... from the stabilizing effect of the Moon on our polar "wobble" (axis precession and tilt angle to the orbital plane) to creating tides which pump billions of tons of seawater in and out of coastal marine habitats worldwide twice daily. It's believed when the Moon formed, it was only a few dozen thousand miles from the Earth itself; at that close range the tides would have been ENORMOUS, literally hundreds to thousands of feet high, and in certain areas could have raged inland for hundreds or thousands of miles on the young Earth. This enormous energy expenditure would have rapidly done two things-- slowed Earth's rate of rotation from about 5 hours down to, in a declining slope like that of a bell curve, toward the current 24 hour day we now have, and it would have gravitationally transferred energy into the Moon, raising its orbit and "slinging it away from Earth" to it's present 240,000 mile high orbit. Due to the smaller mass of the Moon versus the Earth, the Moon was fairly quickly brought to "tidal lock" with one side facing Earth permanently, just as Earth's rotation rate was slowed from 5 hours to 24 hours. As the Moon was accelerated away from the Earth, the gravitational tidal interaction becomes less, and the 'curve flattens out' into the more or less "stable" situation which exists today (though the Moon IS still slowly being propelled away from Earth by tidal boosting and Earth is still SLOWLY losing rotational momentum as a result, so our day length is gradually getting longer, but the effect becomes less and less with distance and time).

Without large moons, it's difficult to see how these planets would be stable enough in their polar axis (yes, they still rotate on their axis, even if "tidally locked", it's just that the rotational rate and the orbital rate are the same, 1:1-- one rotation per orbit, 1 day per year.) to support life. In addition, the previously mentioned massive "tidal pumping" on Earth shortly after the Moon formed would have surged huge masses of seawater hundreds or even thousands of miles inland in places, or thousands of feet up mountains, then let it all rush back out again, creating enormous "tidal scours" through huge amounts of erosion on the early Earth, enriching the oceans with minerals and nutrients freed from eroded rock turned into valuable sediments that were deposited into the early oceans by these 'tidal bores', creating rich deltas and tidal "marshes" and pools that would have been the ideal breeding grounds for life. On a planet with no large moon(s), the only source of tidal energy would be the periodic gravitational interaction with the other orbiting planets (which could be daily or near-daily, depending on the orbital periods) and it would be a greatly reduced and 'weak' tidal force compared even to our own Moon's current tidal pumping, so that too has profound implications for developing the kind of environments suitable for life... barren, rocky shorelines with weak ocean waves lapping gently at the rocks isn't particularly nourishing environments (except to pre-existing life that then moves into those niches, which is possible as it is here on Earth).

To be continued...

OL J R
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Old 02-23-2017, 01:04 PM
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Continued...

Of course the next question is "is there any water?" Without it life, as we know it, is impossible. Life needs the solvent power of water to exist. Just as important is "how much water" because if it's a super-concentrated brine (like the Dead Sea here on Earth or the Great Salt Lake) then it's probably sterile of life anyway. How will that water interact with the environment?? Without tidal pumping from large moon(s), on a tidally locked planet, with only the periodic interaction with other large planets orbiting relatively nearby... what sort of climate and water cycle will develop on a tidally locked planet? Will the oceans simply boil away on the day side and end up frozen as an enormous ice cap on the nightside?? Will stable oceans and lakes form near the terminator in the "habitable zone" of a tidally locked planet? If they do, will those lakes or seas have sufficient nutrients and erosion-formed soils to provide a basis for life? Bare rocks surrounded with placid pools of briney water stirred by a cold wind blowing in from the nightside, lit only by the weak, dim red light of a tiny star doesn't sound like a very promising place for life to thrive...

Since some of these planets "straddle" the habitable zone of the star, it's likely they have very different environments. In our solar system, Venus is around the inner edge of the Habitable Zone and Mars just approaches its outside edge in the lower part of it's elliptical orbit. Earth site nestled pretty much in the middle. Venus, of course, has a runaway greenhouse climate with 900 degree temperatures at the surface and is baked dry of all water. Mars is a frozen desert due to its thin atmosphere and low gravity and lost almost all its water to slow disassociation in the atmosphere due to solar radiation and solar wind stripping away the atmosphere over time due to Mars not having a magnetic field once its small iron core solidified early on. What water remains is frozen in the soil or thin polar caps of mostly dry ice (frozen carbon dioxide). If either had liquid water (which is probably likely to some degree) or life, they've long since lost it. Similarly, those planets near the inner edge of the habitable zone are likely to be more Venus-like, especially being tidally locked (as Venus has a bizarre rotation opposite the direction of every other planet in the solar system (west to east instead of east to west like all other planets) which has never been explained, and rotates extremely slowly, so that the 225 Earth day year is actually SHORTER than the 243 Earth day rotational period (day length). So Venus isn't tidally locked, but rotates VERY SLOWLY from west to east. This would have poor ramifications for life even if Venus were more Earthlike with a similar atmosphere and oceans to Earth-- no tides due to no Moon and no nearby planets, likely very hot due to solar irradiation being closer to the Sun at the inner edge of the habitable zone, and very long days and nights lasting months at a stretch. So it would be in this other planetary system for planets in the inner edge of the habitable belt. Earthlike planets in the middle of the belt would still have issues due to being tidally locked and the low solar energy available, as well as no large moons, but what of planets at the outer edge of the habitable belt? Placing Earth at the outer edge of the habitable belt near Mars' perihelion (but in a circular orbit instead of elliptical like Mars which takes it further away from the sun) Earth would be cold, VERY cold... probably a frozen snowball. Earth would be frozen where it is if it weren't for water vapor, which is a much more effective greenhouse gas than the miniscule amount of CO2 in our atmosphere... In fact scientists believe Earth has suffered at least two nearly complete pole-to-pole glaciations in the distant past, termed "snowball Earths", one shortly after the "oxygen event" that suddenly changed the nature and constituent gases of our atmosphere fairly early in Earth history, and another somewhat later in the Precambrian Period. They believe massive infusions of carbon dioxide and methane from volcanic events broke the feedback effect that leads to "snowball Earth" events and kick-started the water cycle, warming the planet and thawing it from it's frozen prison. Planets orbiting much further away at the edge of the habitable zone would be FAR less likely to emerge from "total glaciation periods" like this, especially on tidally locked planets that would tend to accrue a massive ice cap on the night side anyway. It's possible that ALL the water could eventually be locked up in a massive mountainous Pacific-sized glacier on such a planet, with bitterly cold subzero winds lashing the "sunset zone" that would be the most habitable on planets further in, with only a "small" area near the center of the sunlit side of the planet, perhaps a ring surrounding the central "high noon" desert (where the sun would always be directly overhead) actually being habitable... perhaps only the central area of the desert where the sun would be directly overhead would be habitable... it all depends on the climate and solar energy available, the atmosphere and temperature and amount of water... many variables. At least this "garden spot" (or garden "ring") on the planet would be fairly mild (but windy most likely, virtually incessant wind probably, blowing toward the center of the "high noon" part of the planet-- again a lot depends on the atmosphere and solar energy available-- remember in our own solar system Mars gets about half the solar energy intensity as Earth does, and its winds can be quite fast at times, though not as powerful due to the fact the air is extremely thin). The "garden spot or ring" would enjoy constant sunlight always coming from a never-moving sun almost directly overhead (depending on one's position-- always directly overhead in the center of the daylight half of the planet-- always "high noon" there... ) That could mean a very stable climate, which is both good and bad... good for existing life or ecosystems, not so good for creating conditions for life to start...

It would certainly be a very interesting place to visit... Of course we're assuming that the planets have atmospheres of consequence, magnetic fields to protect them from massive solar flares and radiation and from having their atmospheres stripped away from constant solar wind and irradiation, and that they're not drowned and crushed under a massive carbon dioxide atmosphere like Venus under a pressure of 90 atmospheres and searing temperatures... that they have water in amounts sufficient to provide a hydrologic cycle of some sort, and therefore climate of some type. They could be just bland balls of burning rock at the bottom of an impenetrable atmosphere of poison gas, like Venus, or dry, frozen balls of rock with a wisp of an atmosphere like an Earth-sized Mars... or, interestingly enough, if conditions were right and they accrued large oceans, they could be almost totally covered with water, possessing a large atmosphere that COULD potentially be mostly water vapor and nitrogen or other gases, and could have very dynamic climates with strong ocean and wind currents between the hot eternally sunlit side and the cold eternal night side... with turbulent ocean currents carrying heat from the hot ocean surface on the day side deep into the cold night side, cooling the one and warming the other, with cold water sinking and wending across the ocean floor back to day side... Hot water spreading from the "high noon" area of the planet and giving off massive convection currents and huge amounts of water vapor into the atmosphere would whip up and swirl off enormous hurricanes constantly that would then spin out toward the 'sunset zone' and rain themselves out as they spun over the horizon into the cold night side of the planet... This of course, depending on the severity of the climate, could be quite detrimental to any prospects for life on any small, shallow continents or archipelagoes that might exist... lashed by near constant hurricanes every few days nonstop would be very punishing... Of course, if the weak solar energy on such a planet were to stir things up "just enough", it COULD provide just enough erosion and tidal action (due to frequent storm surge) to create more hospitable environments for life, like monsoon-rain lashed islands... difficult but not impossible. Of course such heavy cloud cover could render even the daylit side virtually dark, especially on a planet orbiting a dim red dwarf, precluding any possibility of photosynthesis...

The possibilities are certainly most intriguing!

Later! OL J R
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Old 02-23-2017, 02:03 PM
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Trappist-1 is a young star, and therefore like other young red dwarfs, a flare star. Those flares would eventually rip the atmospheres off almost all those planets. The article I read did say the 4 inner planets are in synchronized orbits.

I discount any having life and none are probably terraformable.
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Old 02-23-2017, 04:50 PM
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Quote:
Originally Posted by Joe Wooten
Trappist-1 is a young star, and therefore like other young red dwarfs, a flare star. Those flares would eventually rip the atmospheres off almost all those planets. The article I read did say the 4 inner planets are in synchronized orbits.

I discount any having life and none are probably terraformable.


Yep, read up on Trappist 1 after I got done here... only 500 million years old. IIRC the scientists say the Earth took longer than that to cool down from its formation. They wouldn't even have oceans yet, let alone life, by even the optimistic scientist's wildest dream. Being that they're in SUCH close orbit, it's quite likely that they might end up with some of them colliding over time, since even "relatively small" Earth-size planets will tug each other around in their orbits when they're crowded that close together. Remember ALL these planets are orbiting WITHIN the orbit of Mercury in our own solar system... some of them are only separated by about 384,000 miles at their closest approach (1.6 lunar distance) from each other. So close they'd appear about 3-4 times the size of the full Moon in each other's skies as they passed each other in their Trappistcentric orbit. What we may be seeing, is something similar to the early periods of our own solar system, when up to 40 protoplanets orbited our own young Sun until they eventually "sorted themselves out" by either colliding, getting flung out of the solar system, or being decelerated and falling into the Sun. Most of them ended up colliding to form the major planets.

Also read where Trappist 1 gives off most of it's radiance as infrared, near infrared, and some dim red light, all of it at the low end of the spectrum (which figures for a small cool red dwarf star). In addition to the severe flares, it also gives off sufficient X-rays and extreme ultraviolet to probably have cooked the atmospheres (if they existed) and fry the surfaces of the planets anyway. So I'd put the chances of life being found there about akin to finding life on Venus. (and at least Venus had better conditions early on and 4.5 billion years of stability since then).

One interesting thing is, since Trappist 1 is such a small star, it fuses its hydrogen into helium at a very low rate, which explains its coolness and low luminosity. The star should be extremely long lived, lasting 4-5 TRILLION years, til most of the stellar fuel in the universe has been used up. Trappist 1 should be one of the last stars to exist in the era of stars before they all wink out one by one (according to cosmologists anyway). According to them, our own star is about halfway through its lifetime and will swell into a red giant before shrinking into a white dwarf in about another 4-5 billion years. When our own Sun is a burned out ember, Trappist 1 will still be dimly glowing away like it always has at that point...

Since the planetary system cannot be very old, it's POSSIBLE that the planets COULD STILL develop atmospheres and oceans in the future, say in another 500 million to a billion years... of course a lot of that depends on the star system itself, whether it has a cloud of comets and residual water-bearing asteroids surrounding it, and if there are any large planets or nearby stars to disturb the orbits of those comets and asteroids and trigger a "late heavy bombardment" period in the Trappist system similar to what scientists believe happened here on Earth and in our own early solar system, when they believe most of Earth's water accrued. If that is so, and we're seeing an early analogue of our own solar system, then it's not surprising that the inner solar system is swarming with 8 planets, which in all likelihood will eventually collide in some manner and "thin the herd" and settle down into a more stable and thinner configuration (at least if what scientists postulate happened in our solar system is correct and bears any relevance). Then IF there is an Oort cloud and a means of disturbing it sufficiently to send a rain of comets and asteroids into the inner solar system, it's POSSIBLE than in eons to come that at least SOME of the planets could accrue enough water and gasses to form oceans and a stable atmosphere; if the star ages enough to settle down from its flare-prone phase and if the planets possess iron cores sufficient to generate a magnetic field (which may be highly unlikely or impossible on tidally locked or slowly spinning planets-- Mercury has a magnetic field despite its small size (smaller than the Moon, about halfway between Moon-size and Mars-size) despite its very slow rotation rate (Mercury rotates once every 176 days and orbits the sun in 88 days, so two "backwards days" per year), yet almost-Earth size Venus possesses NO magnetic field (and somehow manages to keep its 90 times Earth-density atmosphere, despite being subjected to stronger solar wind lashing constantly at it unprotected, which supposedly blew Mars' thin atmosphere off into space molecule by molecule over time, due to its lower surface gravity and smaller size and lack of a magnetic field to deflect the solar wind). So it's something of a coin toss if the planets could hold onto a substantial atmosphere, given the extreme UV radiation and X-rays from the nearby star, presumably fairly strong stellar wind (even from such a weak star, due to the planets close proximity to the star), and whether or not the planets might or might not have a magnetic field to shield them from the brunt of the stellar wind, assuming the planets would have gravity similar to Earth (mass x density, which are probably pretty close to Earth measurements-- we know they're Earth-sized, but are they close to Earth-density and therefore Earth-mass, which determines how strong gravity is on the surface). It's also assuming they can collect enough gas and water to form an atmosphere at all.

Anyway, it's really interesting to think about...

Later! OL J R
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