Could this hypothetical xoplanet support life?

KTevolved

Yea i was trying to say rain but i didnt know if it would just eveaporate before it reached the surface. When you said earlier several billion years retining would that be with a magnetc field and the several million years without. I was just wondering cus billions vs millions is a huuuuge difference haha. I would think volcanic activity would help replenish water and other gases and if it had a longer bombardment with more icy based comets or asteroids but idk. Thinking about this stuff is really cool, cus we might observe it one day.

onomatomanic

No, the model only covers ordinary kinetic escape driven by heat, nothing else. The difference results from the simplicity of the model, which gives only one hard figure - the watershed between immediate escape and short-term retention. Beyond that, everything is gradual and has to be either intricately modelled or roughly estimated, and I only have the means to do the latter - thus, large error margins. Sorry.

As I said, my best guess is that the seepage would be insignificant even over billions of years, but it's no more than a guess. If so, you don't need to do anything. If you want to err on the side of caution, give the planet more water than Earth had to start with, so that you can let some portion of it escape and still have enough left to go on with.

willstaruss22

Volcanic activity would help replenish Co2 levels and if there are plants that produce oxygen more oxygen in the atmosphere. The increased eccentricity is interesting. You would be closer and farther from the sun than earth is to its own which will have minimal effects. On the close side you will be warmer having more solar enerfy and further less energy. The 80% water would definatly help stay put the water especially if your oceans and seas are deep.

KTevolved

Yes the i was going for more eccentricity to vary the nvirnments more between hot and cold and i would think that the increase in eccentricity would heat the core a little more than if it were not.

KTevolved

So how about nirtogen and oxygen can they stay for billions of years also? I also gave the atmosphere 1.5 bars to be realistic lol. Also how would the eccentricity affect the planet?

willstaruss22

Yes oxygen and nitrogen can stay indefinetly. A 1.5 atmosphere on your planet would keep the oceans in a liquid state and it will rain and have weather systems due to the heating and cooling from the star.

onomatomanic

Eccentricity of 0.08 means that between perihelion and aphelion, orbital distance varies by ~1/6, insolation varies by ~1/3, temperature theoretically varies by up to 30 K. Practically, I'd expect something between 10K and 20K from that source. Definitely noticable; the details depend on the magnitude of your axial tilt and how the equinoxes aligns with perihelion and aphelion.

KTevolved

Yea i should have been more precise with the orbit. It orbits at 1.06 au. So at its nearest it orbits at 0.971 au and at the furthest it orbits at 1.14 au. The only reason the temperature isnt colder is because of the abundance of Co2 and water in the atmosphere. The axis tilt varies from 23-28 degrees because of the moon but its at 25 degrees right now.

onomatomanic

^ Right, but you still need to decide on the alignment. The axial tilt is larger than Earth's, and so would still be the primary source of the planet's seasons, so let me for the sake of simplicity use Earth's months to describe the progress of the orbit.

If perihelion were to occur in March and aphelion in September, say, then in the Northern hemisphere the result would be pretty much be a two-season year: Summer from March to September, winter from September to March, with little in the way of a gradual spring and autumn. In the Southern hemisphere, the result would be the same, just shifted by a quarter-year: Summer from December to June, winter from June to December.

If, on the other hand, perihelion were to occur in June and Aphelion in December, you get something quite different: In the Northern hemisphere, you get the familiar four-season year, except that the difference between summer and winter is far greater. Spring and autumn still occur from March to June and September to December, and with about the same temperatures as those we get. But as the eccentricity-driven insolation changes now add to the tilt-driven insolation changes, you might get temperatures of 55 rather than 35 Celsius in summer and -25 rather than -5 Celsius in winter, in what we would consider temperature latitudes. In the Southern hemisphere, the two changes cancel out, and you might get temperature differences between "summer" and "winter" of no more than 10 Celsius. Hardly worth being called seasons at all.

Overall, if you want a situation like on Earth, in which the two hemispheres are pretty much mirror images of each other, have perihelion and aphelion near the equinoxes. If you want a situation in which the two hemispheres have weather patterns as different as those equatorial and temperate regions have on Earth, have perihelion and aphelion near the solstices.

See how that works?

KTevolved

For earths sake perihelion would occur in March and alphelion in September. Im trying to have the planet be familiar to earthlings while at the same time being very different in terms of climate, weather patterns and gravity. Im still trying to figuer where exactly the tropics and cold regions would be.

onomatomanic

Best guess, your planet would have a single atmospheric circulation cell per hemisphere, instead of the terrestrial three shown below:



It has to be an odd number, and as your planet is significantly smaller than Earth, and as the size of such cells tends to increase with both mean absolute temperature and mean rate of change of temperature with latitudinal distance, one cell seems like the obvious choice.

The result is pretty boring, unfortunately. There'd be a cold Northeasterly everywhere in the Northern hemisphere and a cold Southeasterly everywhere in the Southern hemisphere, without any of the transient high and low pressure systems which give us the unpredictable changes most of us mean when we talk of "weather". The only variations would be seasonal ones, see above, and daily ones due to the day-night cycle. Nothing in-between.

Further, this would constitute a far more efficient mechanism of latitudinal heat transfer than what we have on Earth, so you probably wouldn't get any ice-caps at the poles. If there's land there, it'll be cold desert, if there's water, it'll just be cold. The mid-latitudes should be drier than ours, generally speaking, and should directly give way to the tropics, without an intervening desert belt.

Do you have an idea how your 20% land is distributed, overall?

KTevolved

The 20% land is divided into 2 different continents and there are 2 main oceans separating the 2 continents along with polar oceans north and south. Both land masses occupy regions in between the tropic of capricorn and tropic of cancer passing through the equater they are on opposite side of the planet from each other. There is a 1,200 mile long mountain range cutting across the northern end of one of the continents. There are dozens of small islands scattered in between the oceans most of them are volcanic. Im curious what if we tweaked the eccentricity from .08 down to .02 and left the axis at 25 degrees Also switch the perihelion to january and the aphelion to june? Just wondering what would change then. Btw planet is still at 1.06 au with the thick atmosphere.

onomatomanic

Yes please. No need to go to any trouble, even a picture that's the result of a minute's work in MS Paint is often better than a paragraph of text. You can upload it to e.g. tinypic.com.

KTevolved

I forgot to add the atmospheric composition.
70% nitrogen, 20% oxygen, 5% xenon, 3% carbon dioxide, 1% water vapor and the rest methane carbon monoxide neon argon and trace hydrogen. The xenon is one of the reasons for the denser atmosphere. The oceans also have a salinity of 5-6% idk if that would do anything but im just trying to be more specific. Sorry i couldnt add a picture my mind is better with a picture in my mind then laying down words, hard to explain its how my mind works haha. Hope this gives a better idea of the planet.

willstaruss22

20% oxygen means will have life and the co2 means if you have plants they will grow to potentially huge sizes. Yes xenon will make the atmosphere denser even on its own. I have a website that will show you the atmospheric retention of all the main gases you have.
http://astro.unl.edu/naap/atmosphere...ntionPlot.html
So you can see that xenon, co2, oxygen and nitrogen can be all retained for many billion of years even longer. Water can also be retained but for several billion maybe 5-6 billion years in the atmosphere but there is an ocean to keep supplying, methane will also last because there is life replenishing it just as on earth. Hydrogen will only last a few thousand years and then dissapear. Having 80% water will help absorb the co2 more than earth so if your co2 was reduced to earths level it would be a little colder. Plants will supply oxygen. As for humans settling on its surface we can but there are 2 major factors we will have to get used to, 1 the gravity and 2 the extra heat. The less eccentric orbit will help it be more earth like. Hope this helps better

KTevolved

So with a denser atmosphere does that mean water boils at a higher temperature or does the gravity affect it as well. Say a person lands there and they want to boil water for tea or something, would the boiling point be higher or lower than 100 c? Also you didnt explain what the weather would be?

Mech_Engineer

Water's boiling point definitely varies with pressure, see here:

http://webbook.nist.gov/cgi/fluid.cg...m&RefState=DEF

The boiling point at 0.75 bar for example is 91.8 degrees C; the boiling point at 1.5 bar is 111.4 degrees C.