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rfmcdonaldCentauri Dreams takes a look at the gas giant planet HIP 57050 b, located some 40 light years from Earth in the constellation Ursa Major, that orbits its dim star squarely in the middle of its habitable zone. Could b host a living Earth-like world? It's possible.
Commenters note that such a world would likely be volcanically very active, between its tight orbit around b and tides from its star. This would be quite unlike our Mars, which is much more queiscent. Like Mars, this world would lose its dense atmosphere fairly quickly thanks to its low mass, and so wouldn't be very Earth-like for long. Still, there would be a time, perhaps as long as a couple of a billion years, where the world would be fertile.
Recent work from the Lick-Carnegie team has found that the M-dwarf HIP 57050 is orbited by a Saturn-mass world with an orbital period of 41.4 days. What catches the eye about this exoplanet is its temperature, some 230 kelvin or -43 degrees Celsius, warm enough to place it in the habitable zone of the star. Based on our knowledge of the gas giants in our own Solar System, it’s a natural supposition that this is a world with moons, and if so, their location in the habitable zone draws inevitable comparisons with fictional worlds like Pandora.
[. . .]
Could a habitable moon exist here? Theoretically so, but the paper goes on to note that in our Solar System, on the order of 0.02% of the mass of the gas giants is found in their moons. Run the numbers and you wind up with a moon that is about 2 percent of Earth’s mass, or 1/5th the mass of Mars. That doesn’t sound particularly promising, but in an article in Scientific American, Darren Williams (Penn State) points out that larger moons could form on their own and be captured by a massive planet’s gravity.
We may be looking at that situation in our own system in Neptune’s moon Triton, which possibly arrived where it is today by being captured by Neptune, with a binary object pairing with Triton being ejected in the process. Williams, who has simulated the situation on objects as massive as the Earth, says that an Earth-size moon could form around a gas giant this way, with a secondary object the size of Mars being lost along the way. So while we’re a long way from discovering a moon around HIP 57050 b, we do at least have a world in the habitable zone of its star and the possibility of objects around it that are astrobiologically interesting.
Commenters note that such a world would likely be volcanically very active, between its tight orbit around b and tides from its star. This would be quite unlike our Mars, which is much more queiscent. Like Mars, this world would lose its dense atmosphere fairly quickly thanks to its low mass, and so wouldn't be very Earth-like for long. Still, there would be a time, perhaps as long as a couple of a billion years, where the world would be fertile.
