Wow. Yeah, Wolf 359 is what I've been running with - it is small and dim, meaning its effect on everything else is fairly small, while still being there.Somes J wrote:The dwarf is supposed to be similar to Wolf 359, right? Looking at Solstation, Wolf 359's habitable zone is .005 AU, or only 750,000 km! A quick calculation tells me that if you were 50 million km (1/3 of an AU) from the red dwarf and 40 AU from the Amillian sun you'd be getting more heat from the Amillian sun!
But eeek, the radius of Saturn + radius of Wolf 359 ~= 200,000 km. So that's not very far out at all. I usually neglect the radius of the two bodies when talking about stars, since usually it is nowhere near, but man, not so here.
I want the combined radius to be much smaller than the distance. So if we peg the distance at radius * 100 = 20,000,000 km = ~0.14 AU.
The star is going to have to be a lot brighter it looks.
Let's just calculate a luminosity. Assume we want Earth like solar flux at that distance; 1.4 kW / m^2. The sphere at .14 AU has a surface area of... 4 pi r^2 = 5.5e21 m^2. Multiply that by our flux to get a total solar output of 7.7e24 watts.
Wolf 359's output is ~ 4e23 W. So to make this work, the star has to be about 20x brighter. (That makes it 2% that of our sun.) Know any real life candidate star with similar output that we can yank some numbers from?
Let's go back to how bright this would be in the amillian sky. We'll just use the power output divided by the surface area of a sphere with radius of 30 AU: 0.03 W / m^2. 1/47000th that of the sun. That works out to apparent magnitude of -15.04; over 6x brighter than the full moon. Wow.
What about at the far point of its orbit, at 60 AU? Inverse square means it will be 1/4 that, since distance doubled. Incredible, it is still brighter than the full moon! You'd only get truly dark nights during the times of the year when the suns are lined up (so the red star is only up during the day).
Maybe we should move it farther out. It'd make a mission there even longer, but at over 30 years one way (with Hohmann orbits), we're already looking at something much bigger than a 5 year mission, so it is all about the long haul as it is.
Since cranking up the brightness probably means cranking up the mass, moving it out helps stability of the inner system too, so probably a double good move.
I went looking for a binary star to look at distance, and came across Struve 2398 B on Wikipedia. It's luminosity is in the right ballpark. Its mass is .3 sol and its radius is .54 sol. Average distance of about 56 astronomical units,[citation needed] and the eccentricity of the orbit is 0.70. It says it gives out x-ray flares, mang (i guess wolf 359 does too). But at least here's some ballpark numbers to work with. It is also a red dwarf.
So 72 AU far out and 40 AU near. Magnitude varying from -14.4 to -13.1. So between about that of the full moon to almost 3x the full moon. Not too bad.
But yeah, this result gives some more interesting fun in that dwarf's orbit, so yay. I'll adjust my simulator for the new numbers and see what happens tomorrow.
Mine agrees, for what it's worth. The new numbers above should give more fun to play with; just hopefully, it won't throw Saturn out of the system too now!Could you even get a stable orbit that close? I tried running a 750,000 km orbit on a .1 Sol mass star on gravity simulator and it wasn't stable. Then again, I didn't adjust the sun's diameter.
Me like.Maybe a tide-locked Mercury-like world. The nightside might be a significant source of volatiles in the form of frozen volatiles left behind by impactors in craters - since it that side of the planet never faces the sun such ice could easily exist despite the close proximity to the sun.
Right - that's part of why it is there. The tides will be rather mean to it. I'll have to crunch some numbers and see how mean.Would imply higher tides, unless it was farther away from the planet. Just something to consider.
Could do it. I'm thinking about moving the asteroid belt inward too, but it could. See, if I can pull it off, I'd like to move the first jovian a bit in, and it can shove the asteroid belt inward with it. This makes them more easily accessible for manned missionsI'm thinking a Mars-like world.
Yes, certainly. Let's do the superearth out there.I'm thinking maybe a smaller world, more like Uranus/Neptune sized or somewhat bigger (30-40 Earth masses), or maybe even a large icy superterrestrial (< 8 Earth masses) instead of a gas giant. I'm thinking that the gravitational effects of the binary may have stunted the planet's growth somewhat, in the same way Jupiter might have done for Mars. Also it makes the system seem a bit less like a complete mirror image of ours, which I think makes it more interesting.
win. It can have a nice moon system too perhaps.I also think a nice idea would be to have an outer icy asteroid belt beyond the final gas giant, where the gravity of the companion star may have prevented a planet from conglomerating, again in something of a mirror of the effect the gas giant has on the inner system.
Suggestion: a hot tidelocked superterrestrial planet inside the orbit of the hot Jupiter. This fits with a theory that a hot Jupiter may push material in front of itself as it spirals in, leading to the formation of hot inner terrestrial planet from that material. And it's just an idea I find appealing. Especially since that close to the star the hot Jupiter may not be able to retain any moons, so it gives something interesting in the vicinity besides the gas giant itself.
Hell, I asked for a candidate star above, and you have one here that is decent. Mass and radius are both 0.46 sol, luminosity 0.025 sol, so a bit more than my one above, but not by much.I also think the hot Jupiter should be moved further in if we want it to actually be hot. .3 AU isn't going to be particularly hot even for a large red dwarf. The M2 (relatively big and bright) red dwarf Lalande 21185 has a habitable zone at .22 AU according to Solstation. I'd make its orbit < .1 AU.
With a brighter star, they'll be even more fun room. sqrt(20) = 4.4, so it could probably go out further. Maybe; depends on what the other sun does.As a hot Jupiter migrates inward it may drag in large quantities of volatile-rich material, leading to quite wet terrestrial planets. I imagine the red dwarf might have several icy terrestrial planets, and beyond that there might be a family of small gas giants (maybe Uranus/Neptune sized). With up to 3 AU to form in and such a dim star this might be quite an extensive family. If we go with the outer planet stunting model, there might also be an icy superterrestrial planet close to the edge of the system, inward of the outer asteroid belt. So perhaps:
[snip]
This all sounds really good though. a little more tweaking to the star and we'll have something out here.
I'm open to anything cool. I've been assuming Neptune in my calcs, but anything works.Also: clarification: do you want a true hot Jupiter or more of a hot Neptune or maybe a hot Saturn? Personally I lean toward the latter; they might be more common in the universe.
That sounds cool.If you want something a bit more interesting than a Mercury-like world, perhaps the innermost planet could be a tidelocked Venus-like world. Alternately we could have a terrestrial planet that had suffered a truly massive impact, knocking off its outer layers, so it could indeed be like Mercury but closer to the size of Mars or larger, perhaps large enough to retain some sort of atmosphere. A Mars-sized or larger metal-rich and dense tidelocked world with a thin atmosphere would be nicely unlike anything in our solar system.
Right; hell, Saturn is pretty close to Jupiter sized itself.I don't think swapping the planets should be necessary so you can have rings - I don't see why a Jupiter-sized planet couldn't have a Saturn-like ring system.
So in the morning, I'll see about updating my simulation and collecting it all again. This is so cool.