The Riddle of Super-Earths: Clues from GJ 9827

Brian G Turner

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#1
Super-earths are some of the most common exoplanets found:



And yet super-Earths remain the most mysterious of exoplanets, because we don't have anything truly to compare with in our own solar system.

However, the star GJ 9827 appears to have no less than three of them - and it's a star that's long been observed and so may provide clues to the ever enigmatic super-Earths.

Gassy or metal? Newly found planets straddle the line for super-Earths
 

BAYLOR

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#2
Super-earths are some of the most common exoplanets found:



And yet super-Earths remain the most mysterious of exoplanets, because we don't have anything truly to compare with in our own solar system.

However, the star GJ 9827 appears to have no less than three of them - and it's a star that's long been observed and so may provide clues to the ever enigmatic super-Earths.

Gassy or metal? Newly found planets straddle the line for super-Earths
Are any of theses super Earths capable of sustaining life as we know it?
 

Venusian Broon

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#3
I wonder how skewed this data still is, (presumably, I assume) due to measurements and techniques not being abled to pick up lighter planets? As these get refined and better we could get a swing towards Earth-sized and smaller.

However the main point which I think will remain no matter what, is that, actually, our solar system is perhaps not the 'standard, average' sort of solar system out there - which is excellent news for our theories about solar system formation and evolution. We now have loads of other examples to ponder and hypothesis with...

@BAYLOR - it will depend on quite a lot of factors and information that I don't think we have. Are the planets, as the article discusses, gassy or metallic? 'Life as we know it' probably would prefer a metallic planet, but at those sizes and densities, the gravity would be significantly higher - everything geologic and biological will be short, squat and low to the ground. What sort of atmosphere do these planets have? etc. :D
 

Brian G Turner

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A couple of interesting observations about super-earths:

1. Stronger gravity may make it difficult for any civilization on such planets to enter space - there's actually a story on that today: No Way Out? Aliens on 'Super-Earth' Planets May Be Trapped by Gravity

2. I also wonder whether the relative passing of time would be significant - I remember Alan Moore used this in his halo Jones series for 2000AD. Simply put, how differently will time pass on a super-earth 4x our planet's mass and how that might relate to the Fermi Paradox (though coupled with 1., both might be relevant together).
 

Parson

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#5
A couple of interesting observations about super-earths:

1. Stronger gravity may make it difficult for any civilization on such planets to enter space - there's actually a story on that today: No Way Out? Aliens on 'Super-Earth' Planets May Be Trapped by Gravity

2. I also wonder whether the relative passing of time would be significant - I remember Alan Moore used this in his halo Jones series for 2000AD. Simply put, how differently will time pass on a super-earth 4x our planet's mass and how that might relate to the Fermi Paradox (though coupled with 1., both might be relevant together).
Interesting thought Brian. If we carry that to it's logical conclusion than smaller planets would have a greater opportunity to house a space faring intelligence. Of course too much smaller and you have trouble keeping an atmosphere around your planet. So .... do we again come back to the idea that earth is just about as perfect as it can be for intelligence to thrive, or is that simply a limitation of the way we observe things. If we stay with the very nearly perfect set of circumstances then we might leave a slightly larger opening for the Femi Paradox to be less paradoxical.
 

Brian G Turner

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So .... do we again come back to the idea that earth is just about as perfect as it can be for intelligence to thrive, or is that simply a limitation of the way we observe things.
I think it's more the case that selective pressure has favored humans - but change the parameters of our physical environment and other species might be favored instead. :)
 

Venusian Broon

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1. Stronger gravity may make it difficult for any civilization on such planets to enter space
It's a fair comment with our current knowledge... Perhaps 'heavy' civilisations might rather invest in 'light craft' and get things into orbit with superlasers??? :) But who's to know what the universe has in store as we look further into it. I do think there's loads of things we've still to discover that may help us make spaceships!

2. I also wonder whether the relative passing of time would be significant - I remember Alan Moore used this in his halo Jones series for 2000AD. Simply put, how differently will time pass on a super-earth 4x our planet's mass and how that might relate to the Fermi Paradox (though coupled with 1., both might be relevant together).
There is a difference, but it's tiny. So there so that you'd have to adjust your GPS satellites a tiny bit more, but you'd not notice it as a human. I think you have to be very close to the event horizon of a black hole to get 'significant' effects.

So .... do we again come back to the idea that earth is just about as perfect as it can be for intelligence to thrive, or is that simply a limitation of the way we observe things.
My belief is that all intelligences, wherever they are, will think subjectively that they are in a perfect position :D. I think it's always best to work from the Copernican principle first. Stops us getting too big-headed!

A question that does arise, for me, is that: is intelligence a viable long-term strategy for life? I believe that unthinking bacteria and single celled life is, and will, remain the 'dominant' life form in the whole Universe. :)
 

LordOfWizards

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#8
Perhaps 'heavy' civilisations might rather invest in 'light craft' and get things into orbit with superlasers?
Interesting idea VB. Keeping in mind that this is all either conjecture, or calculated guessing, if intelligent life has evolved on these "Heavy Earths", They would likely have evolved as a lighter (lower mass per member) species than us since selection would likely favor that smaller beings (not necessarily more squat, wider, etc.) would be more mobile in a higher gravity circumstance. It would then follow that their crafts would be smaller, lighter of course. Yet regardless of the mass/weight of a being like that, the escape velocity would be proportionally higher, and like you say, would need different tech to reach orbit and beyond. One option harks back to something we did way back in the 1950s: Joe Kittinger's Balloon to space.
 

LordOfWizards

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#10
I did leave it open for that end of the scale, yes. :) Although, if you have ever observed insects (wingless) walking around (who has that kind of time these days :D) the terrain becomes a bit of a barrier to motility. So, I guess I was picturing something a little larger - maybe somewhere between a field mouse and a monkey? (depending on the intensity of the gravity on the "super Earth")

You make a good point though (even if you were only joking). It can be hard for a species like us to imagine sentient creatures that are much different than us having intelligence to the extent that we do or even beyond, as well as language. If you have never read Fuzzy Nation - John Scalzi, I'd recommend it.
 

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