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New Paper Explores The Prospects For Life Around M-Class Stars (arxiv.org)
Long-time Slashdot reader RockDoctor summarizes the significance of a new paper describing "The Habitability of Planets Orbiting M-Dwarf Stars":
Although Star Trek had a minor smattering of "M-class planets" -- a designation that tells one nothing of substance -- "M-class star" is a much more meaningful designation of color, with two size classes, the dwarfs and the red giants... an M-dwarf of 1/10 the mass of the Sun will burn for around 1000 times the time that the Sun does... Therefore, if humanity ever meets an alien species, the odds of them coming from an M-dwarf [system] are already high. If humanity ever meets an alien species that has been around a billion years longer than us and has technology we can't even dream of, then the odds of it coming from an M-dwarf are overwhelmingly high.
This new paper offers "a comprehensive picture of the current knowledge of M-dwarf planet occurrence and habitability," pointing out that most of these stars are apparently orbited by planets packed closely together, with "a paucity of Jupiter-mass planets and the presence of multiple rocky planets." And more importantly, roughly a third of those rocky planets are orbiting in a "habitable zone" -- far enough away from their stars to support liquid water.
This new paper offers "a comprehensive picture of the current knowledge of M-dwarf planet occurrence and habitability," pointing out that most of these stars are apparently orbited by planets packed closely together, with "a paucity of Jupiter-mass planets and the presence of multiple rocky planets." And more importantly, roughly a third of those rocky planets are orbiting in a "habitable zone" -- far enough away from their stars to support liquid water.
"Although Star Trek had a minor smattering of "M-class planets" -- a designation that tells one nothing of substance ..."
Wrong. If you have an M-class planet, you should at least be able to find Roddenberries there.
#DeleteChrome
... which is counteracted by the increased number of M-dwarfs, and their increased lifetime.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Although Star Trek had a minor smattering of "M-class planets" -- a designation that tells one nothing of substance
Then why did you bring it up?
And actually, in universe it tells you plenty. It tells you humans and most of the other bipedial humanoid life-forms which smatter the galaxy can survive on the surface and breathe the atmosphere. It also tells you it's likely to be littered with polystyrene rocks or to look a lot like parts of California.
systemd is Roko's Basilisk.
M-dwarves last for a trillion years while a sun-class star is good only for a few billions (ours is 4.5ba old and in a billion years Earth will be uninhabitable). Which matters exactly zilch when the whole Universe is only 13.8ba old, and you need a few star lifetime iterations to produce enough "metals" (for astronomers anything above hellium is a metal) for life to be viable.
There's indeed more dwarves than any other kind of stars, but then, their habitable zones are much smaller and they have other problems that are harmful to life in our sense, so they don't have any advantage. Wake me up in a trillion years or two, then life will be strongly biased to dwarf stars.
The creatures outside looked from Alt-Right to Antifa; but already it was impossible to say which was which.
Short version - some close-in planets will be tidally locked, but not necessarily all of them. And (as discussed), the fact that M-dwarfs covers more mass variation than the next three classes of stars combined (F-dwarfs, G-dwarfs like the Sun and K-dwarfs) so it would be safe to expect a considerable variation in the behaviour of planets around M-dwarfs.
Consider tidal locking in a system with an M-dwarf star, a "hot Jupiter" and our Planet of Interest (PoI). If in orbit around either the hot Jupiter or the star, the PoI might become locked. But with the three in relatively close interaction, the PoI could be disturbed between locking to one, or the other, or alternating, or spinning irregularly. Feel free to use a planet with an irregular - literally chaotic, even - rotation in an SF scenario of your choice.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Humanity could never meet an alien civilization. We cannot travel even a significant fraction of the speed of light. And due to Physics we never will be able to. Sorry, but that is reality.
Or is there a reset point. When the technology enables them to destroy themselves, at which point it just just a matter of time. Maybe thousands of years, but not billions.
And the intelligence is unlikely to be biological. How long will it be before humanity is replaced by computers. Not within 100 years, but it is hard to see it not happening within 1,000 years.
http://www.computersthink.com/
You're the idiot. M stands for Minshara, a Vulcan word.
Only the State obtains its revenue by coercion. - Murray Rothbard
Just because an M-type dwarf will burn for 1000 times longer than our sun doesn't necessarily mean that any civilization in orbit around an M-type star is already older than we are.
This is probably true. But those stellar generations are not the generations of common stars (dwarf stars, up to, for example, the Sun's mass), but the lifetime of larger, faster evolving stars. You don't get metals further up the periodic table than carbon from a Sun-mass star. The lifetimes of such stars (say, more than 3 Sun masses ; I forget where the exact dividing line is for stars getting up to burning silicon to iron. It's somewhere near that mass.) is much shorter - more like a half billion years, The time for the ejecta from a supernova to become incorporated into the next generation of stars is more significant than the lifetime of the stars.
Interestingly, there is a fair correlation between the metallicity of a host star and it hosting a "super-Jupiter," but that correlation breaks down for smaller (Neptune-size and Earth-size) planets. While they still form around stars with a solar-similar metallicity on average, they're not more common around higher metallicity. That's odd. There's something going on there that works against the obvious expectation of how things go. I don't know about you, but I'd take that as a sign to pay more attention to observational data than theory.
The study was (as is normal) carried out with the assumption of the stability zone of liquid water as the criterion for "habitable zone". No other constraint. You might be interested in finding something that would find William Shatner attractive - even if only as food - but that's not the only thing "life" could plausibly mean. A prokaryote-grade of organism with a non-nucleic acid genetic system would be far more interesting than something that beat Shatner at chess with an RNA-world type genetic system.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Consider tidal locking in a system with an M-dwarf star, a "hot Jupiter" and our Planet of Interest (PoI). If in orbit around either the hot Jupiter or the star, the PoI might become locked. But with the three in relatively close interaction, the PoI could be disturbed between locking to one, or the other, or alternating, or spinning irregularly. Feel free to use a planet with an irregular - literally chaotic, even - rotation in an SF scenario of your choice.
So that explains the irregular seasons in the Game of Thrones universe... Winter is coming.
Specialist Mac support for creative pros, Melbourne
Never having read a word of it, or seen a second of it, I thought "Game of Throwns" was set on Earth?
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
You're the idiot. M stands for Minshara, a Vulcan word.
I don't believe that came up until Enterprise. But, in any case, in the original series they said "Class M".
#DeleteChrome
Game of Thrones seems to be set on an Earth-like world, however with dragons, undead and a degree of magic. They have winters that are sometimes brief and other times plunge the world into a freeze that lasts for generations...
Specialist Mac support for creative pros, Melbourne
I thought that meant survivable to all lifeforms not wearing a red shirt.
Try "Cycle of Fire" by Hal Clement.
It seems to me that it is a safe bet that the known limitations of Physics will never be overcome, to such an extent that we will be able to dominate the galaxy. I.e. FTL travel doesn't seem like it will ever be more than science fiction. Many phenomena are governed by a dipole curve, where things start slowly, then hit a tipping point where they rapidly accelerate until they reach a new level of stability. You see this in economics, in Physics / Chemistry, in the evolution of new species, etc.
Why are we alone then? If alien civilizations had arisen 1 billion years before ours, and developed technology beyond our dreams, wouldn't they at least leave a trail of some kind?
Something to consider is that radioactivity decreases with the age of the universe. There is a certain probability that a % of an element will be a radioactive isotope when such elements are created. Less and less heavy elements are being created as the universe ages, and existing ones decay. This means that life will arise more easily.
http://www.fourmilab.ch/docume...
...the development of life of a level that supports advanced intelligence probably needs a certain level of energy intensity across the spectrum in order to develop and that an M-class star doesn't provide that, meaning they would stall at a fairly low level of life and remain there.
E Proelio Veritas.
You seem to be making a completely baseless assumption that all solar systems are the same size. The planets around an M-dwarf orbit much closer than those around our sun. It's observed fact, not theory.
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Does this suggest (however lightly) that perhaps we (humanity) should be looking not to M-class stars but to K-class stars for more intelligent lifeforms and more advanced civilizations?
E Proelio Veritas.
OBAFGKM.
E Proelio Veritas.
What's the problem with tidal locking though?
I once read that the backside would be so cold that the atmosphere condenses there. This is not what happens on Venus though. The dense atmosphere evenly distributes the heat around the whole planet, making the temperature nearly the same everywhere.
Thinking about Earth I would expect that a constant pattern of air streams could form which transfers the heat between hot to cold areas.
I was under impression that Jupiter-size planets are useful in in star systems where you hope to get life. They catch a lot of space debris (up to moon size), preventing some (most?) of it with colliding with rocky, life-bearing planets. Avoiding serious extinction events or even blowing up entire atmosphere looks like healthy thing for fragile, growing life.
Here we read about 'planetary systems characterized by a paucity of Jupiter-mass planets', but there is no mention of space guard role they fulfill. Is it overrated or we just don't know enough about their importance to put it into scientific paper?
Chaotic rotation... G. David Nordley's "Calendar of Chaos". The scientists had a betting pool on the exact time of the next sunrise. (This wasn't a planet, though, I believe I recall it was Saturn's moon Hyperion.)
Yes, what indeed is the problem? 'It isn't Kansas any more' as some dog who never went to school once said. If the environment is within the liquid range of water (NB - pressure not counted ; H.sap is moderately labile in this respect, and as long as you don't change presure at more than a factor of 2 per month ... small fucking deal.)
Oh, it's unfamiliar. Well [hand gestures indicating "big", "mammalian sexual activity", and "redistribution of cards between players".
[Atmosphere condenses at pole-of-cold] First approximation. Second approximation is that there is heat transfer. Third approximation is that it's a complicated question. And that's before you look at complicated orbits, and complex geology.
Yes, freezing out on the cold-of-pole isn't impossible. But it's by no means inevitable.
Stop dragging reality into a discussion about reality - you'll drag Slashdot (kicking and screaming) into reality.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Copyright is not only theft. As a form of censorship, it's a crime against humanity. ... i cant say it totally compares but for instance the statistics used for crude forex prediction take all data over time to define "pivot points" regardless of the real world circumstance, practically considering the numbers from the post-war period equal to the numbers from the pre-2008 period equal to the numbers of post 2008 equal to the numbers of today
i like your style
by the top comments i can see this must have been pre-election day in the states ?
i wonder on the statistic however, as we are talking about alien life, how valid b/c
which imo makes no sense so in this particular case id say if you were looking for similar carbon-based life maybe it holds a little value qua probability but if one would be talking alien life thats totally beyond omega (point, not "goood") as far as my layman-ass can see
i think, imo and as my not so very humble opinion (at times)
yay for the racial slur btw, its very constructive but i am all up for free speech to make it more easy to point out the clowns, i dont think that will ever change
Free speech was meant to be free for all... how can anyone grow up in a nanny state ?