Author Topic: Is this planet habitable? (Read 15409 times)

destroyer83 · « **on:** September 09, 2015, 10:45:33 PM »

I just made a planet based off a story I wrote, (I know I am not the first, nor will be the last), and I was fiddling and refining it is Ubox², and I was wondering if in it's current state, it would be habitable for humans. Or, if it wasn't habitable for humans, what adaptations would be required for life, and eventually civilizations, to survive and thrive on that planet.

So, here are the relevant details for the planet, plus a picture of the planet itself at the end. (Otherwise it would needlessly take up space (no pun intended) where facts could be.)

The basics
Name: Drakya
Mass: 3.78 Earths (yeah, probably a deal-breaker right there)
Radius: 8335 km
Density: 9.31 g/cm³
Surface Temp: 11.5-15.0 Degrees C
Effective Temp: -43.1 Degrees C (not totally sure what part that plays, but temp is important when considering habitability)
Total Velocity: 9.67 km/s
Rotational period: 23.9 hours

Gravity

Surface Gravity: 21.7 m/s²
Escape Velocity: 19 km/s
Orbital Peroid: 203 years (the reason for this will soon become apparent)
Periapsis distance: 64.3 AU
Apoapsis distance: 66.0 AU

Axis

Obliquity: 15.0 degrees
Augment of Obliquity: 0

Atmosphere

Atmosphere mass: 6E+18 kg
Surface Pressure: 1.47 atm
Greenhouse effect: 58.0 degrees C
Infrared Emissivity: 1.00

Materials: Iron: 65.2%
Silicate: 34.8%
Water: 0.0195%
No organics or hydrogen.

Star: Gachab (Same basic stats as Achernar)

Moons: 3

Moon 1: Ilopert
Mass: 2.15 moons
Radius: 2658 km
Density: 2.01 g/cm³
Surface Gravity: 1.49 m/sec²
Periapsis distance: 85142 km
Apoapsis distance: 86305 km
Relative total velocity: 4.2 km/sec

Moon 2: Tokala
Mass: .425 moons
Radius: 1063 km
Density: 6.35 g/cm³
Surface Gravity: 1.89 m/s²
Orbital period: 7.04 days
Periapsis Distance: 229288 km
Apoapsis Distance: 254194 km
Relative total velocity: 2.37 km/sec

Moon 3: Tessid
Mass: 1.09 moons
Radius: 1997 km
density: 2.40 gm/cm³
Surface Gravity: 1.34 m/s²
Orbital Period: 46.7 days
Periapsis distance: 827450 km
Apoapsis distance: 880221 km
Relative total velocity: 1.33 km/sec

Given that are all the relevant factors considering habitability (I think), it's now up to you, what do you think of the habitability of this world? And if not by humans (who I think would be turned off by the sheer size of the thing) then what adaptations would be required if a hypothetical species were to live on this world?

Have fun theorizing!

Physics_Hacker · « **Reply #1 on:** September 10, 2015, 09:05:31 AM »

Is it orbiting two stars? Or if not, why does it have such a large orbital period and still be relatively habitable in temperature? Having two moons bigger than ours might make he axis more stable than needed, suppressing seasons, but the temperature is about right and so is the water content. The atmosphere is a bit thick, though, and the planet is yes, quite large for human life.

destroyer83 · « **Reply #2 on:** September 10, 2015, 02:27:29 PM »

No, it is not orbiting two stars, it is orbiting one massive blue star (not a giant, but still 6 and a half times the size of the sun)

For clarity's sake, I will give the stats of the star.

Mass: 6.7 suns
Radius: 3,372,528 km
Density: 24.3 kg/m³
Age: 37.3 million years
Surface temp: 18,688 Degrees Kelvin.
Total Velocity: 0.378 m/s
Rotational Period: 83.7 days
Surface Gravity: 78.2 m/sec²
Escape Velocity: 726 km/sec

And a picture for reference

Also, I believe that the size alone of the moons wouldn't effect the axis too much, given that, combined, all three moons would just about equal a scaled-up version of our moon. Now, the proximity of Ilopert (the largest moon to Drakya) is the main worry in this case, it's almost 4 times CLOSER to the planet than the moon is to earth, and Tokala (the 2nd and smallest moon around Drakya) is just under half the distance, and Tessid, (the farthest moon, and the one only slightly larger than our moon) is actually DOUBLE the distance between Earth and the moon. So, what do you think the effects of the moons on the planet are?

Physics_Hacker · « **Reply #3 on:** September 10, 2015, 07:01:29 PM »

Well the star is too blue, as in, no life as we know it would be able to even form there if it had any sort of DNA, because radiation from the star would tear apart the organic molecules, so that's a complete deal-breaker right there. And on the moons, because the majority of the mass is much closer than that the moon is to our planet, even though it's a smaller moon/smaller combination, it would have a much, much stronger effect on the planet, giving a possibly slightly less detrimental effect than what I previously stated, but still much much stronger than our moon, and would still suppress seasons more than our moon does.

destroyer83 · « **Reply #4 on:** September 10, 2015, 07:44:15 PM »

Interesting statement about the color of the star, "Too blue", your statement about there being too much radiation is probably right, but that raises the question, can life be supported around a blue star at all without the life turning into radioactive man?

Physics_Hacker · « **Reply #5 on:** September 10, 2015, 08:07:29 PM »

Well...Life definitely wouldn't be able to arise on it's own, unless every single organism had some sort of thick partially metal shielding, which would make it hard to move around, seeing as the planet is already 3 times as massive as earth and therefore has about 3 times as much gravitation force, but humans colonizing there would be a different story, as we have shielding that is adequate enough to at least shield us from our sun's radiation, although there would be a ton more around a blue star than our sun, since the brightest part of the stars spectrum would be blue or ultraviolet. (which is what is so deadly) And no, it's not exactly radioactivity, but the light literally breaks down DNA at the atomic level, causing life to not even get started, unless it started deep under oceans, slowly moving up into the sun and adapting it's physiology as it went. It'd be extremely difficult for life to get started even, possibly not even getting a chance to get beyond microbial life, as stars like that only survive a few million years, 1 billion tops, before going supernova.

destroyer83 · « **Reply #6 on:** September 10, 2015, 08:32:20 PM »

Facinating! This is all very cool! Thanks for your help! I would say that if you wanted to show planets of your own which you wanted to debate the habitability of, by all means do so, but you already know so much (and taught me so much, these topics are so cool!) that you would probably be able to figure out at a glance if it was habitable for not. But still, go ahead, have fun, and thank you!

Physics_Hacker · « **Reply #7 on:** September 11, 2015, 03:02:56 PM »

Any time! Any more questions you might have on this or anything else, I can try to answer (because of course I don't know everything, no one does XD) And it is pretty cool, that's why I'm so into it :-)

destroyer83 · « **Reply #8 on:** September 11, 2015, 05:01:34 PM »

Ok, an interesting question, I tried again, trying to actually replicate the star that I actually stated it was in the story (it turns out I misremembered it as blue) Said star is HD 171238, so I placed it in that system, and I placed the planet HD 171238 actually has, then Drakya itself (same stats for the planet) and then the moons, (I re-generated them, hoping for some smaller moons) placed the moons, and the new second moon had a thinner atmosphere than Drakya itself, but it was FAR above 100 degrees C, while the moons without atmospheres were still below freezing, and Drakya itself was around 25 degrees C, how does that happen? (if that helps, it was only about half the size of our moon).

Physics_Hacker · « **Reply #9 on:** September 11, 2015, 07:41:38 PM »

Maybe tidal heating? I'm honestly not sure, as that sounds more like a bug than actual scientific data, as if it has a thinner atmosphere, even with a ton of tidal heating involved, it should still be colder than the planet itself...

destroyer83 · « **Reply #10 on:** September 11, 2015, 08:13:04 PM »

Another interesting point with the re-do, in this system, there is a planet that is 2.6 times the size of Jupiter with a rather eccentric orbit, (Apoapsis is 3.5 AU, Periapsis is 1.5 AU. (This is actually the real planet in the system, so I really can't do anything about that.)) Unfortunately, no matter what I do, it seems that the shape of Drakya's orbit gets more and more oblong. From a fairly round orbit around 1.2 AU all around, it turns into a rather oblong orbit with a periapsis of .195 AU, (so close that the sun robbed it's second moon from it) to an Apoapsis of 1.87 AU. Needless to say, it is no longer habitable. The star is also very similar to the sun. So, I don't think this will work either. I think the reason the orbit is going batty is because of the influence of the larger planet (HD 171238b) But it doesn't change orbit very quickly, it only became uninhabitable over a couple of hundred years. The Semi-major axis, though fluctuating, also remained stable, though. So, is it the influence of this "Mega-jupiter"? Note, to try and mitigate the influence of "Mega-jupiter" I also inclined the orbit almost 90 degrees, so it's Apoapsis would be as far as possible from "Mega-Jupiter"'s Periapsis, when those aligned in any sort of way.

Physics_Hacker · « **Reply #11 on:** September 11, 2015, 08:36:35 PM »

Indeed it is the influence of the much larger planet that is making it get an eccentric orbit, I had a similar effect in a trinary system where I had a gas giant that started out too far from it's star and was pulled on until it had a very elliptic orbit, and eventually threw one of my outer terrestrial planets into a comet-like orbit XD (gladly, it wasn't the habitable one in that system)

Also, take into consideration that a couple hundred years isn't very long at all in astronomical terms, as Neptune and Uranus took millions of years to switch places into their current positions. (In case you didn't know, Uranus and Neptune once were opposite in order from semi-major axis than they are now when they first formed, changing places during around the same time Jupiter and Saturn got into a 1:2 resonance, all of this sending asteroids and comets flying everywhere, some to slam into Earth and our relatively newborn moon, causing both to suffer many many impacts, some quite major)

destroyer83 · « **Reply #12 on:** September 11, 2015, 09:04:21 PM »

But yeah, unfortunately, it looks like that since "Mega-Jupiter"'s Periapsis is too close to the habitable zone, it looks like that this system is uninhabitable as well...shame.

destroyer83 · « **Reply #13 on:** September 12, 2015, 09:35:20 PM »

Interesting thing I found, I started fiddling around with the "Magnetosphere" and I realize now I completely forgot about that. However, that raises some interesting questions. First, how big should my magnetosphere be? how much help does it give when trying to block solar radiation? Second, How much Radiative power is acceptable for a habitable world? What options can I take to reduce it if necessary?

Physics_Hacker · « **Reply #14 on:** September 13, 2015, 01:05:37 PM »

Earth's magnetic field isn't all that strong in comparison to something that could shield a planet around an O-type star like yours' radiation, and so the magnetic field itself would be so strong it would harm human life. But life that started there and is adapted to it like we're adapted to our magnetic field is a different story...it could happen, especially because your planet is so much bigger than Earth, but getting the core of the planet to churn that violently would be difficult, considering the fact that your planet's rotation period is so similar to Earth's, but not much faster whatsoever, meaning it would be harder in general to have a stronger magnetic field than us.

destroyer83 · « **Reply #15 on:** September 13, 2015, 07:12:26 PM »

alright, and in a couple of do-overs, I did switch out the star to a G-type main sequence star.

Physics_Hacker · « **Reply #16 on:** September 13, 2015, 08:20:37 PM »

Much better for Earth-like life :-)

destroyer83 · « **Reply #17 on:** September 15, 2015, 08:48:00 PM »

As has been explained. Thank you. One more question, how much radiative power is acceptable for a life-giving planet?

Physics_Hacker · « **Reply #18 on:** September 15, 2015, 09:38:23 PM »

Actually, I'm not sure about that...I believe that has to do with albedo, in which case it doesn't matter as long as the albedo doesn't end up making the planet too cold or hot.

destroyer83 · « **Reply #19 on:** September 15, 2015, 10:21:26 PM »

Right, mine is at .23 right now. Also, I do believe that the Magnetosphere does play a role.

Physics_Hacker · « **Reply #20 on:** September 16, 2015, 01:27:25 PM »

Earths albedo is in the 30's. And yes, magnetosphere does play a role, since all stars give off that DNA-tearing radiation (even if it isn't much) like I told you about the blue star.

Darvince · « **Reply #21 on:** September 16, 2015, 07:46:34 PM »

Radiation should go down to acceptable levels to have a habitable planet around a low to mid A-type star, if you have a strong magnetosphere (which larger planets will tend to have much more often).

Also, planets can't even form around O or B stars because of even more reasons than stated here. The most important of which does tie in to the insane radiation levels, in that this also means the solar wind is very strong, so the protoplanetary disc will be blown away before it can even coalesce. Plus, according to current models of planetary formation, O stars don't live long enough for planets to form in the first place, as by the time it goes supernova they are still in the protoplanetary phase with lots of accretion and collisions.