Celestia Forums

HD 28185 b (gas giant planet), with earth-like moon?

This theory would be very nice, but, should to exist a moon with life around of a gas giant massive that it generates magnetic fields, producing enough radiation.

Can exist life in those conditions?

Yep, radiations are the main problem with earth-like moons orbiting around jupiter-like planets... However, the moon could have its own magnetic field who minimize the radiations from the giant. And a thick atmospher might help too...

But these conditions makes such a planet very doubtful, and if life appears in this system, it would be with high mutation rates...

Not entirely.
If the moon is massive enough, say the size of the Earth or just a tab bigger and with an Earth strength magnetic field and it was out far enough in orbit it could be very possible. I have been working on the HD 28185 system add-on on and off for over 2 years. When I started looking for a system with just the right specs to flip the bill this was the one. I even put a habitable moon orbiting it before Extrasolar Visions did there update on HD 28185 b a few months back. The other thing that makes larger more metallic cored moons possible in this system is that the star HD 28185 is more than 1.5 times as metallic as our own Sun. This means there was more in the way of raw metals during its creation to be incorporated into planetary cores. More metal means a better chance of having a nice strong magnetic field to protect the planet/moon from all kinds of radiation.
The key of course is how much radiation is B generating. Just because it is 5 times Jupiter?€™s mass doesn't mean it is putting out five times the radiation. Because of its make-up it may actually put out less radiation than Jupiter. Being that it is believed that B has a great deal more water in it than hydrogen. It is believed that Jupiter?€™s massive amount of radiation and its strong magnetic field comes from a deep well of liquid metallic hydrogen. If HD 28185 B has less liquid metallic hydrogen and allot more water at depth than the radiation levels may be lower. Water is a natural radiation blocker as well.
We just don't anything more about extra solar gas giants yet. Jupiter is our only measuring stick and who is to say Jupiter is the norm when it comes to these giant planets. There are just so many variables to work with. What would happen if Jupiter was moved closer to the sun? What would happen if it was moved father from the sun? How would this affect it and its make-up and its atmosphere? How would this affect its magnetic field? At this point we have nothing but conjecture. But we can hope that this is the best system for finding such a moon because of its placement from its sun is right in the middle of the habitable zone. The other thing is that this system is about 130 light years away. It?€™s not like it is right next door, maybe down the street a ways. So we are not going to be sending an envoy there anytime soon. But hopefully in the next 10 years or so we may know if there really is a possibility of a habitable moon being there.


Don. Edwards

Perhaps the moon is tidally locked to the planet. Half of the planet will be permanently shielded from the radiation, while the other half will permanently exposed. Two completely different hemispheres.

The key of course is how much radiation is B generating. Just because it is 5 times Jupiter?€™s mass doesn't mean it is putting out five times the radiation. Because of its make-up it may actually put out less radiation than Jupiter. Being that it is believed that B has a great deal more water in it than hydrogen. It is believed that Jupiter?€™s massive amount of radiation and its strong magnetic field comes from a deep well of liquid metallic hydrogen. If HD 28185 B has less liquid metallic hydrogen and allot more water at depth than the radiation levels may be lower. Water is a natural radiation blocker as well.

From what I gather of the subject, the radiation environment around gas giants is largely down to the strength of their magnetic fields and the strength of the solar wind. Namely, the magfield captures the atomic particles of the solar wind and accelerates them to high velocities, and these accelerated particles smack into the moons.

So if you put Jupiter in Earth's orbit, I'd suspect that the radiation environment on the galilean satellites would be a lot worse than it is now, because it's closer to the sun. If you moved it out to Neptune's orbit, it wouldn't be quite so bad because the wind is less powerful/dense there (assuming it goes by inverse square law)

i remember hearing that uranus is kaput or something like that, and thus probably emits no radiation. is that true? If so, would such a gas planet be a better parent planet for an earthlike moon than a jupiter-like planet?

Hmm, I think I'll have to search for something to read and point to about the radiation around gas giants. As far as I understand, this radiation is made of trapped, high speed electrons and protons (from captured solar wind) that bounce from pole to pole in the gas giant's magnetic field. I'm not sure what the level of X-rays or gamma rays is due to synchrotron radiation.

Assuming an Earth-like moon, with the same magnetic field and atmosphere, I can think of three things that can help protect the surface and thingies on it:
- Its own magnetic field deflects charged particle radiation (like our own van Allen belts). There are short times of pole flip though...
- Its own atmosphere would block charged particles (like for aurora and cosmic rays) and also X-rays and gamma rays. That's why Chandra, XMM and Integral are in orbit.
- Sufficient distance from the gas giant itself might help reduce the problem. You trade off a longer day for lower radiation.

The radiation count should only apply to unprotected astronauts, spacecraft and airless moons.

Spiff.

Spaceman Spiff wrote:Assuming an Earth-like moon, with the same magnetic field and atmosphere, I can think of three things that can help protect the surface and thingies on it:.......

But, potentially a close gas giant will bring:

Evil Dr Ganymede wrote:So if you put Jupiter in Earth's orbit (as HD 28185 case). I'd suspect that the radiation environment on the galilean satellites would be a lot worse than it is now, because it's closer to the sun.

yes!!, I agree, close orbits (gas giants) generates superflares and more radiation:

The magnetics fields around stars with giant planets in close orbit are likey to be even more complicated, with some lines connecting the two bodies.

a) At times motion of the planet or of the ionized gases in space (white arrows) can force two fields lines together, allowing them to break from one configuration and reconnect in another.

b) This process injects energy into the sorrounding plasma, accelerating charged particles and giving off a burst of high-frequency radiation.

The auroras on that moon would be amazing from two sources of radiation and charged particles, no? Maybe you can do something to the nightside graphic Don... I am certainly no expert on comparative planetology, but I would imagine a high spin (and constantly heated core due to tidal forces) iron core in the Earthlike moon could create a sufficient environment for some life to form, not to mention some cool vucanism...