New Paper Explores The Prospects For Life Around M-Class Stars (arxiv.org) 69
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.
Hows about Make YOUR Life matter (Score:1)
setup your home as a "safe zone" (outside lights/cams decently setup landscaping ect) and work in your neighborhood to increase the peace (heck if you want to be snarky setup a little office hut with doughnuts and coffee). Instead of griping work to fix things.
100K folks will come to a protest but 100 folks won't come to a work day
Ummm, OK... (Score:1)
Re: (Score:2)
Re:Ummm, OK... (Score:5, Insightful)
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.
Re:Ummm, OK... (Score:5, Interesting)
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 [nature.com] 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.
Re: (Score:1)
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
Re: (Score:2)
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.
Re:Not putting a spin on things (Score:5, Interesting)
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.
Re: (Score:2)
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.
Re: (Score:2)
Never having read a word of it, or seen a second of it, I thought "Game of Throwns" was set on Earth?
Re: (Score:2)
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...
Re: (Score:2)
Try "Cycle of Fire" [wikia.com] by Hal Clement.
Re: (Score:2)
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.
Re: (Score:2)
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 pla
Re: (Score:2)
Summary is incorrect (Score:2)
"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.
Re: (Score:2)
Yup! The first thing that came to mind upon starting to read the summary, and went for a comment, but, it was the 5th comment posted ;)
Obviously, the 4 earlier posters should turn in their geek card, Futurama is essential material...
Trek's M-class tells you plenty (Score:5, Funny)
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.
Re: (Score:1)
Re: (Score:3)
And to be fair, California is pretty nice. A good variety of biomes, plenty of arable land, fresh water, etc. "How much like California is it" is, in practice, probably a great definition for the habitability of a planet.
Re: (Score:2)
If Star Trek has taught me anything, it is that I like mini skirts a lot, and also nearly every alien world looks a lot like a rock quarry.
Likewise, Dr. Who agrees: companions seem to prefer mini-skirts and most alien worlds almost always look like rock quarries.
That's good enough for me.
Never meet (Score:1)
Re: (Score:2)
So says the mud monkey, https://en.wikipedia.org/wiki/... [wikipedia.org], 115 years after the first aeroplane. Yep, uh huh, sure, http://mentalfloss.com/article... [mentalfloss.com], mud monkey physics. Sorry but your reality will always be based upon your perception of it, as narrow and primitive as it is. Will we go faster than gravity, yes PS the speed of gravity is the fastest that light can go, so speed of gravity is the measure not speed of light. A child with their hands over their eyes, you can not see them, hence they can not see
Re:Never meet (Score:5, Informative)
We could spend the next thousand years developing technology, populating the Solar System with our robots, then travel at 0.01c to the nearest 10 planetary systems, and still not have a species which is 1% older than today.
That's unobtanium-free physics, but I do gloss over the difficulty of crewing and running a generation ship for the thick end of a millennium. It might be easier to develop some form of suspended animation for wombs, and ship frozen embryos for robots to develop, once the robots have built a sufficient space industry at the destination.
I'm sure that I'm never going to see humanity's First Contact moment. If I wasn't dead when it happens, I'd be astonished if any human which even knew it's 21st century ancestors names were involved. (I don't know the names of any of my ancestors even 5 generations back, let alone 30 or so).
A species doesn't need to travel at a significant fraction of c in order to colonise the galaxy. Our society probably couldn't do it in any meaningful sense (are we the same society as a thousand years ago - do you speak Old English, or Norman Frankish?), and maybe our species would have speciated into multiple descendant species by the time they get into other spiral arms. But that isn't "never" - just a very long term plan.
Re: (Score:2)
Within a few hundred years we should be able to grow animal bodies to specification, as well as scanning and storing human personalities. The first ship to a remote star could be very small. Just an assembler which makes larger assemblers, guided by signals from home. The first humans to make the trip would be essentially teleported to their destination.
Its a shame that we are missing out on this by such a short time.
Re: (Score:2)
But sending whole people to other stars is just extremely di
Re: (Score:2)
Frozen wombs (and associated heart-lung machines) with a bucket full of frozen sperm and eggs. The technology is here already.
It's a "6 vs 2x3" question if we'd improve the technology in the millennium or two while the machine (plus eggs and sperm) was in flights, but fundamentally that's a software issue not the hardware in flight. If the labs on Earth come up with a better way of treating the gametes, uplo
Re: (Score:2)
Only the very highest level of control from "home" (see end note) would be necessary. Near total autonomy would be necessary.
Hmmm, The amount of data to be transmitted, and the error-checking needed to ensure that a "personality" had actually been sent, is high. A pretty steep obstacle. Why bother? Why not just send some tissue cultures, some nu
Re: (Score:2)
"Meet" can be interpreted to include any form of communication. For two sufficiently advanced cultures, there's even the theoretical possibility of transmitting the information necessary to construct the alien at the other end.
Re: (Score:2)
We currently can't travel at a significant fraction of the speed of light, but look up the 1960s Project Orion. That was a plan for a spaceship to fire off nuclear bombs for propulsion. It was expected to reach a significant fraction of C. Modern physics says we aren't gong faster than light, not that we aren't going to achieve a speed that can manage interstellar travel.
We can also have generation ships, or possibly automatic ships with crews in some sort of stasis or being frozen. The laws of physi
Can any Civilization last 1,000,000,000 years? (Score:2)
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/ [computersthink.com]
Re: (Score:3)
You're the idiot. M stands for Minshara, a Vulcan word.
Re: (Score:2)
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".
Just because (Score:2)
Re: (Score:2)
M class planet designation (Score:1)
Advanced aliens / technologies do not exist (Score:2)
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 al
Re: (Score:1)
I suggest that.... (Score:2)
A thought just occurred... (Score:2)
I meant F-class.. (Score:2)
Re: (Score:2)
Do you have a rationale for making this suggestion. E.G. some biological process unique to "advanced intelligence" and which requires ... well it sounds as if you mean green- or blue- coloured light?
I know of no biological process unique to "advanced intelligence", for a start. Onegaishimasu - educate me.
Lack of Jupiters considered harmful (Score:2)
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
Re: (Score:2)
I'm not sure that there is such a role.
In the history of the Solar system - the only example we have a good understanding of - the orbital interactions of Jupiter and Saturn were (probably) responsible for the "Late Heavy Bombardment" (LHB) of the inner solar system. But the oldest fossils are found from times not long (~ 1/5 to 1/4 of the then-age of the solar system) after that, and there are hints (well, two hints, both moderately controversial and disputed)
Re: (Score:2)
Thank you for insighful answer.
I tried to look for some 'reputable' sources talking about importance of gas giants, but best thing I was able to find so far is something like http://www.dailygalaxy.com/my_... [dailygalaxy.com], with "Two NASA astronomers recently suggested[...]" "life-bearing planets may be rare" and other quite vague statements.
Re: (Score:2)