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Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

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Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#111

Post by kybernetikos »

mcv wrote: post #93
loxias wrote: post #71

Earlier quoted context omitted.

I never claimed to have proof, just that it's true. ;-) Personally, it "feels true" that life exists as a undeniable consequence of statistical thermodynamics (see: http://www.englandlab.com/uploads/7/8/0/3/7803054/2013jcpsre... referenced in https://www.quantamagazine.org/a-new-thermodynamics-theory-o... ). But I know I'm an engineer, not a scientist or mathematician. I'm perfectly comfortable with things being true…

I still have my doubts. I agree it feels true, and yet every "earthlike" planet found so far is nothing like the Earth. How many exoplanets have been found, and how many of those are Earth-size planets with a large moon in the habitable zone of a sun-like star? Because it's entirely possible that all of those are necessary. Because as inevitable as life may seem, it's also fragile. Practically the entire universe is…

> How many exoplanets have been found, and how many of those are Earth-size planets with a large moon in the habitable zone of a sun-like star?

I think this is down to how we look at the moment. One of the main ways we find exoplanets is to notice the star dimming with a regular frequency. This gets harder as the orbital time increases, as you need multiple observations of the planet transiting the star to conclude that it's a planet. This means that the vast majority of the exoplanets we know about have relatively short orbital periods, and the characteristics that go with that (e.g. they're close to their stars, therefore less likely to have moons, and if we consider them to be in the 'habitable zone', then their stars are relatively dim).

Actually, the fact that we've found so many exoplanets that fit in the relatively limited criteria that we can detect, suggests to me that there are probably a lot of exoplanets of all kinds, that we're just not as good at detecting yet.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#112

Post by nick889996544 »

JumpCrisscross wrote: post #5
CyanBird wrote: post #4

15 day orbit, 170 day planetary rotation, that's an interesting one Sucks for the amount of radiation ofc Would be interesting to hypothesize of it being a larger mercury like planet than a earth like one Please some more up to date astro-duders out there, is the James Webb currently capable of direct spectrography of exoplanets? We can do spectrography during the transit I am aware, but direct spectrography, is that…

> is the James Webb currently capable of direct spectrography of exoplanets? Yes [1]. [1] https://www.sciencenews.org/article/james-webb-space-telesco...

Yes, but... Wolf 1069B is much smaller and closer to its star than this one, so we probably couldn't observe it with Webb.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#113

Post by adastra22 »

loxias wrote: post #69
TheOtherHobbes wrote: post #64

Earlier quoted context omitted.

https://astrobiology.nasa.gov/research/life-detection/ladder...

Yeah. I found and read that before my above comment (and skimmed some of the associated paper[1]) but all that says is direct detection hasn't been attempted since Viking, and that most good signals require in situ or sample return. It still doesn't answer my question! "astrobiologists distinguish between direct detection of life and biosignatures". The highest methods in terms of strength of evidence obtainable with…

Direct observation means, well, observing it directly. Seeing living cells in a microscope. Growing it in a Petri dish. Genetic testing, if it turns out it has DNA or RNA like us.

Within our own solar system that generally means sample return, or sending people with a full biology lab. For an extrasolar planet? I don't think the astrobiology community is of a single mind regarding what should count as direct observation there. We're not sending people or doing sample return for thousands of years. One common opinion I've heard is that seeing an atmospheric spectrograph indicating the presence of biomarkers like oxygen and methane within the habitable zone would be a bio signature, but multi pixel imaging of the planet would be required to claim direct observation. I'm not sure this is a very strong scientific distinction, however.

I'm not an astrobiologist btw, but I used to work at astrobiology.nasa.gov. Small world!

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#114

Post by lamontcg »

defrost wrote: post #52
moloch-hai wrote: post #40

None of these "habitable" planets is really plausibly habitable. In particular, orbiting so close, they are all tidally locked 1:1 to their star, presenting always the same face. If they have any water, it is frozen on the dark side. But they might have no water anyway because they (might!) have no magnetic field to fend off the solar wind that would take away all their hydrogen, as happened to Venus. Earth has its b…

Tidal locking doesn't equate to "always presenting the same face". For example, > Mercury .. is tidally locked with the Sun in a 3:2 spin–orbit resonance , meaning that relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun. > As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two M…

> it rotates on its axis exactly three times for every two revolutions it makes around the Sun.

that doesn't change the argument being made by much. that is still pretty terrible for consistent temperature variations. an extremely long day-night cycle is just about as bad.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#115

Post by lamontcg »

moloch-hai wrote: post #40

None of these "habitable" planets is really plausibly habitable. In particular, orbiting so close, they are all tidally locked 1:1 to their star, presenting always the same face. If they have any water, it is frozen on the dark side. But they might have no water anyway because they (might!) have no magnetic field to fend off the solar wind that would take away all their hydrogen, as happened to Venus. Earth has its b…

> None of these "habitable" planets is really plausibly habitable.

They can plausibly have life, though, but it may not get anywhere near as far as life on Earth has gotten. That is still scientifically interesting.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#116

Post by lamontcg »

rich_sasha wrote: post #94
loxias wrote: post #30

Earlier quoted context omitted.

Over the course of the past 2 decades we've gone from "perhaps some day we'll find extra solar planets" to "most if not all stars have planets". JWST's already found water. At this point it's no longer a matter of if but when extrasolar life will be confirmed, and with which instrument. Might be JWST, might be WFIRST, might be HabEx.

One thing that gives me pause for thought: even here on Earth, we are all, likely, descendants of a single organism: https://en.wikipedia.org/wiki/Last_universal_common_ancestor . It doesn't necessarily mean that the 0-1 creation of life happened exactly once on Earth (maybe it happened many times but the other lineages died out), but I think it makes this argument likely. We see a near-infinite menagerie of differen…

It may be the 'LUCA' is very nearly the ideal early life form and RNA/DNA are the right way to do things. Just like water is pretty unique.

Or alternatively, the first successful organisms on a planet out compete and literally eat the other organisms to extinction.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#117

Post by moloch-hai »

Dylan16807 wrote: post #110
moloch-hai wrote: post #70

Earlier quoted context omitted.

Looking at the hundreds of moons defines "locked" without qualification to imply 1:1. Mercury is literally the only body in the whole solar system in any sort of more complicated "lock". So, no, it really is about word games.

If you don't care about "word games", I suggest you stop arguing about "locked" and focus on the actual point, which I rephrased for you. The actual point is about prevalence. > hundreds of moons > literally the only body They are all moons, not planets, and not in different star systems. That's not enough to make conclusive statements about exoplanet spin. That statistic is more relevant to the word games but I'm no…

Only 1:1 locking is of any interest here. All these exoplanets are certainly so locked. Whether life can arise on such a planet is of course unknown, and will remain so until we find any, but it seems unlikely to me.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#118

Post by moloch-hai »

pantalaimon wrote: post #79
moloch-hai wrote: post #40

None of these "habitable" planets is really plausibly habitable. In particular, orbiting so close, they are all tidally locked 1:1 to their star, presenting always the same face. If they have any water, it is frozen on the dark side. But they might have no water anyway because they (might!) have no magnetic field to fend off the solar wind that would take away all their hydrogen, as happened to Venus. Earth has its b…

> So actually-habitable planets must be much, much rarer, among those announced, than astronomy departments' PR crew would have us think That’s not the conclusion you can draw from that. With the methods we currently have we can only really spot exoplanets if they are very close to their star and also reasonably big in relation to the star. That means super-earths close to red dwarfs. There are very likely many more…

As you quoted yourself, "among those announced". Life arose here, on a planet not among those announced, or like them.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#119

Post by Dylan16807 »

moloch-hai wrote: post #117
Dylan16807 wrote: post #110

Earlier quoted context omitted.

If you don't care about "word games", I suggest you stop arguing about "locked" and focus on the actual point, which I rephrased for you. The actual point is about prevalence. > hundreds of moons > literally the only body They are all moons, not planets, and not in different star systems. That's not enough to make conclusive statements about exoplanet spin. That statistic is more relevant to the word games but I'm no…

Only 1:1 locking is of any interest here. All these exoplanets are certainly so locked. Whether life can arise on such a planet is of course unknown, and will remain so until we find any, but it seems unlikely to me.

> Only 1:1 locking is of any interest here.

Agreed, what matters is what percentage of these planets are 1:1 locked.

> All these exoplanets are certainly so locked.

How do you know? Just citing moons in our system isn't enough.

Re: Wolf 1069B: Earth-mass planet in the habitable zone of a nearby, low-mass star

#120

Post by moloch-hai »

Dylan16807 wrote: post #119
moloch-hai wrote: post #117

Earlier quoted context omitted.

Only 1:1 locking is of any interest here. All these exoplanets are certainly so locked. Whether life can arise on such a planet is of course unknown, and will remain so until we find any, but it seems unlikely to me.

> Only 1:1 locking is of any interest here. Agreed, what matters is what percentage of these planets are 1:1 locked. > All these exoplanets are certainly so locked. How do you know? Just citing moons in our system isn't enough.

Easy, 100%. Do you imagine that fusion occurring in the parent body makes any difference? Tidal locking involves nothing but gravity and friction.
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