We May Have Underestimated the Dangers of Red Dwarf Solar Flares
- Thread starter Spinward Flow
- Start date
Information like this makes me consider how narrow the min/max the lifeforms of Earth have to exist.
And for some reason, I'm also pondering if I should let this affect any Traveller universe I interact with.
This is a great video, thanks for sharing @Spinward Flow .
And for some reason, I'm also pondering if I should let this affect any Traveller universe I interact with.
This is a great video, thanks for sharing @Spinward Flow .
Spinward Flow
SOC-14 5K
Right now, research is pointing towards Terra native life being sustainable under G and K type stars.
- O
- B
- A
- F
- G
- K
- M
A type stars start getting into the 1 billion years or less of life span regime, which may be enough for single celled life to get started, but probably isn't long enough for complex multicellular life to evolve before the star needs to shift from hydrogen fusion to helium fusion in the core (which is bad for planets, since that will move the "habitable zone").
F type stars might produce a bit too much UV radiation for life (as we know it) and could have some unforeseen effects on atmospheric photochemistry that our form of terrestrial life may not appreciate. F type stars also fuse hydrogen into helium faster, so they have shorter lifespans as stable main sequence stars before moving into helium fusion in the core. This reduces the "window of opportunity" for life (let alone complex life) to evolve in these star systems.
So right now, it's kind of looking like the G and K type stars are the "best bets" for being able to find stable planetary habitats under atmosphere.
Well, I had this on my mind recently...
Main Sequence stars, when they get old enough, either burn out into white dwarfs or expand into giant stars before becoming white dwarfs, at least that's what I think happens (mostly from a Traveller perspective).
1. For the former, I take it that all planets in the life zone get frozen or worse, and the whole system is basically the outer zone now.
2. For the latter, any planets swallowed by the gas giant either crumble into dust or become dead spheroid rocks, which are revealed when the giant star shrinks to a white dwarf. I'm not sure what would happen to any gas giants or stars in the close orbits that would get swallowed. I also think that a main sequence that becomes a giant doesn't really have an inner zone or life zone, because they were swallowed by the star, so any planets would be outer zone types. I'm only thinking about this because of the different ages of stars and all of the posts on this general subject in the CotI. And also because I wonder if something like this could affect Traveller somehow, even though I don't think I'd allow it personally. But for me it also kind of makes sense, which is also why I'm making this post. Plus, it could make for some interesting systems.
Main Sequence stars, when they get old enough, either burn out into white dwarfs or expand into giant stars before becoming white dwarfs, at least that's what I think happens (mostly from a Traveller perspective).
1. For the former, I take it that all planets in the life zone get frozen or worse, and the whole system is basically the outer zone now.
2. For the latter, any planets swallowed by the gas giant either crumble into dust or become dead spheroid rocks, which are revealed when the giant star shrinks to a white dwarf. I'm not sure what would happen to any gas giants or stars in the close orbits that would get swallowed. I also think that a main sequence that becomes a giant doesn't really have an inner zone or life zone, because they were swallowed by the star, so any planets would be outer zone types. I'm only thinking about this because of the different ages of stars and all of the posts on this general subject in the CotI. And also because I wonder if something like this could affect Traveller somehow, even though I don't think I'd allow it personally. But for me it also kind of makes sense, which is also why I'm making this post. Plus, it could make for some interesting systems.
Spinward Flow
SOC-14 5K
L Stars (most of which are suspected of only D+D, D+T, and T+T fusion) extend down from 2000k to about 1300 K.
T Stars (T0-T5) are suspected of only D+T and T+T; cooler (T6-T9) of only T+T or even no fusion. Runs to about 700 K. Methane gas in the "stellar" atmosphere.
Y "Stars" are brown dwarves ... but still radiating plenty of IR and a little bit of dim redness. They radiate enough to have a liquid water zone....
From what I can tell, L stars don't flare much, and T barely fuse anyway...
T Stars (T0-T5) are suspected of only D+T and T+T; cooler (T6-T9) of only T+T or even no fusion. Runs to about 700 K. Methane gas in the "stellar" atmosphere.
Y "Stars" are brown dwarves ... but still radiating plenty of IR and a little bit of dim redness. They radiate enough to have a liquid water zone....
From what I can tell, L stars don't flare much, and T barely fuse anyway...
Spinward Flow
SOC-14 5K
My understanding is that brown dwarfs are capable of fusing Lithium (Li) in order to generate internal heating, but you're right that their entire spectrum of emissions is shifted way down into the IR end of the spectrum (because of black body radiation at their surface temperatures). It IS possible to have a liquid water habitat zone around such brown dwarfs, but you're talking planet to moon types of orbital distances, rather than "1 AU" type of Sol to Terra orbital distances.
The trick is, even if there is a "planet/moon" in the liquid water zone around a brown dwarf, any kind of life dependent upon photochemistry to photosynthesize is going to be COMPLETELY DIFFERENT from the chemical processes and photosynthesis optimizations we see on Terra. The shift in radiated spectrum is just too great, so a "different chemistry of life" would be necessary (assuming there's any such thing present).
There are at least 5 different chemicals we call Chlorophyll (a-d, f), and a few other reactions that store energy from light chemically. Carotenoids can do so, but don't do the oxygen cycle the same, if I understand correctly, and I've seen science vids covering two other non-Chlorophyll chemicals with different color response. (phycoerythrin and phycocyanin).
It seems extremely likely that life will be based upon the same common 40-some amino acids, since at least 8 have been identified as existing in vacuum. Tryptophan's unique spectrum has been detected at 1000 LY, and "more than 10" amino acids found on an asteroid sample return. (Note: The Aurore Sourcebook for 2300 has Marc et al speculating on alien biochem... and mentioning the various amino acids in the 80's... which lead me to keep an eye out for things on it.) And that's likely to lead to many of the same photosynthetics. Assuming that the flares don't
The response range of Chlorophyl will be adequate through at least L5... L stars peak output is in the deep red to near infrared... but they have plenty of their spectrum still in the red portion of Chlorophyll's response. As we get to T class? ISTR that the temp (and hence light spectrum) is below that of the photosynthetic's needs.
Also, even the deep crustal bacteria use the same range of amino acids as the rest of life as we know it; there's little reason to assume novel chemistry when our biochemistry isn't uniquely terrestrial in its core components.
It's likely that we'll see xeno-algae with largely the same chemistry, but less energetic overall...
https://www.stsci.edu/~inr/ldwarf1.html has some good illustrations of wavelenths for L types...
Also worth a side note for others: Before L became the default, some astronomers and catalogues were using M10-M19 for the range of stars now largely being called L0 to T5... but not all. https://courses.lumenlearning.com/suny-astronomy/chapter/the-spectra-of-stars-and-brown-dwarfs/ is a good dive on it.
Building Blocks of Life Found on Samples Collected From an Asteroid
The find suggests that amino acids could land on Earth on meteorites
Spinward Flow
SOC-14 5K
I agree. It is EXTREMELY LIKELY that any carbon based life will rely on the same amino acids we know about on Terra. There may be some exceptions elsewhere, but the broad similarity is a reasonable hypothesis/assumption (until we get evidence to the contrary, of course).
What I'm questioning is how those amino acid "building blocks" get assembled for xeno-life to take advantage of deep IR luminosity to enable (and then optimize for) photochemistry useful to that xeno-life is also extremely likely to do things with those same amino acids quite differently from how they're used by life on Terra.
Or to put it another way ... same bricks, different patterns.
Keep in mind that the Main Sequence comprises the entire range from O through M / L. It is really only the lower mass M-type Main Sequence dwarfs that simply evolve directly into Degenerate (White) Dwarfs because they do not have enough mass to generate the core pressure necessary to fuse Helium. And Brown Dwarfs (~ M7 or later) don't fuse light Hydrogen, so they never end up as naked Degenerate Dwarfs (although their cores probably are Degenerate).
The O and B type Main Sequence Stars end up as Giants and Supergiants, and eventually as Supernovae after fusing (in successive layered shells) all the way up to Iron, leaving behind neutron stars or black holes.
The F through K type Main Sequence Dwarfs are the ones that eventually begin to fuse Helium (and possibly Carbon and Oxygen for the heavier types) that expand and eventually leave behind Degenerate (White) Dwarfs after their outer envelopes have become so distended that they become gravitationally unbound.
Essentially, although they will go through a "Blue Dwarf" phase shortly before fusion shuts down as the remaining Hydrogen closer to he surface is fused toward the end. This will likely make them more radiant (briefly).
As the star expands, the Outer Zone would become an Inner Zone, and any Outer Zone worlds located there would be forced to evolve based on the new set of conditions.
When I published solis, I used current data, now from what I have read, much is out dated. Recently I read a paper on Arxiv (I don't trust youtube) that the gravitational flexing can keep the core liquid, and the torsional effect of an atmosphere can cause the planet to rotate; this can give a planet a magnetosphere that modifies the flare. It could be an important input. Biology is too complex, we don't understand it, the last 20 years have overturned much of what we think we knew. Same as now with webb, it is showing the universe is so complex to almost defy understanding. We might have to come to terms with that we will never understand it, time is not on our side.
kilemall
SOC-14 5K
I’m of the God does not roll dice school of thought, there is an order and logic to how and what life evolves to. We just have a very parochial haven’t climbed out of the crib perspective, we get out there and we will get educated.
I'd split the difference. It's all knowable, if we had all the data. We don't -- and maybe can't -- have all of it, and thus won't have perfect knowledge. On the other hand, it may be knowable enough with what data we eventually can access, to yeild useful understanding and predictions (that hold up to progressively better data).
Astronomy is lucky in that it is unlikely to go down the weird hole biology did in the 19th and 20th century with genetics. We have seen a lot of our assumptions about how planetary systems work change. Given time we will resolve the data from the current, and future telescope missions. Going to system would provide the best information, that is true, maybe someday we will be able to go.
Of the conditions for planets, mass is really important, for having a liquid core, and keeping an atmosphere; Mars is too small, the Earth is almost too small, many of the exoplanets we see are larger, what they call "Super Earths". Also it is fascinating to think about how long does life need to evolve? Many of the M-type stars have had long periods where their planets could have been life sustaining before becoming tide locked, and their atmospheres stripped by flares. I call those tomb worlds, and who knows what wondrous art, and science, may be left behind, something for players to find.
Of the conditions for planets, mass is really important, for having a liquid core, and keeping an atmosphere; Mars is too small, the Earth is almost too small, many of the exoplanets we see are larger, what they call "Super Earths". Also it is fascinating to think about how long does life need to evolve? Many of the M-type stars have had long periods where their planets could have been life sustaining before becoming tide locked, and their atmospheres stripped by flares. I call those tomb worlds, and who knows what wondrous art, and science, may be left behind, something for players to find.
There are a number of astronomers who've noted that at much more than 1.3 Gees chemical rocketry isn't going to get to space by direct ascent... well, not without some rather interesting¹ choices. Most orbital class rockets initial thrust is around 1.2 Gee on the pad; the first 20 m are the hardest... (Peak is often over 7 Gee.
¹: Interesting being things like Fluorine+liquid lithium. Or nuclear-thermal scramjets. And yes, NASA did consider a tripropellant, adding liquid hydrogen to fluorine and liquid lithum at some 1650 kelvin. It's a wicked ISP of 541 seconds... but its toxic, its waste includes Hydroflouric acid, Lithium Fluoride and more due to interactions post-bell... Rocketdyne did the testing.
I always thought it was clever when I my Dad told me that by design a vehicle like the Saturn V is too heavy to lift off. The engines can't generate enough thrust to launch the vehicle.
The magic is simply that as the fuel is consumed, then the vehicle gets lighter and lighter, until it finally passes the threshold of being able to lift off.
Besides having to baste in its own juices for the start of the launch, it lowers the overall initial impulse into the rocket for a smoother lift off and ascent.
I always thought "boy, those rocket guys sure are clever!".
Or FOOF (alternately, O2F2) AKA Dioxygen Diflouride). [Things I Won't Work With: Dioxygen Difluoride -- Derek Lowe at Science.org]
Do read the whole thing, if you like witty writing about extreme chemistry.
Tory II A and Tory II C, for use in the (cancelled) Supersonic Low Altitude Missile (SLAM).
Yes, we tested them. They actually worked. We thought better of it, though. (Design and testing between 1957 and 1964).
Crazy Cold War stuff.
(All links to Wikipedia.)
I have read this as well. Maybe if they could never do it, they would not dream of it? Though we imagine things as a defence mechanism, our ancestors if hearing a noise in the dark, imagined a threat and ran away. Those that didn't then the threat got them. I think it might be possible to do a multistage space plane, not SSTO, except more difficult. Our space programs are a sideshow for the missile programs:
Korolev with a V2 engine in '45 (spent years in the Gulag, until they decided they needed him). People used the vehicles they already had. Maybe another world could do it differently, it is possible.
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