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originally posted by: alpha015
So.. the other day I read that Proxima Centauri released a huge flare last year, decreasing the chances of existing life in Proxima b
What do you think about it? I also read that the flare lasted 2 minutes.. what if the flare happened in the part of the star that was not facing Proxima b? Proxima Centauri rotates every 82 days.. I think that maybe the flare might have been released on the oposite side towards empty space (or other exoplanets)
originally posted by: ziplock9000
a reply to: alpha015
I think when the educated experts tell you that it "decreased the chances of existing life in Proxima b" and you're just a random person on the internet, you have to go with the experts.
The flare in question, like solar flares, was a burst of broadband electromagnetic radiation. The magentosphere (no matter how strong) has no effect on electromagnetic radiation.
You'd need a hell of a magnetosphere, much much more stronger than the Earth ever had.
originally posted by: carewemust
a reply to: stormcell
Can the space station stop circling the Earth and "hide" on the side that will not be affected by a massive incoming solar flare...until the danger has passed?
originally posted by: Ross 54
The flare of Proxima Centauri would reportedly have been about ten times as strong as those that reach Earth from the Sun. Adequate protection by an atmosphere and magnetic field at Proxima b would seem unlikely. Finding one flare of this size from Proxima Centauri strongly indicates that a great many others would have happened, too. Their cumulative effect would probably be to erode any atmosphere from the planet, causing it to leak away into space.
It's been calculated that there is roughly an 85 percent chance of finding Earth-like planets in the Alpha Centauri system, around either of the larger, Sun-like stars, rather than the red dwarf, Proxima. These would be far enough from Proxima to avoid the harmful effects of its flares. They would, in the scale of interstellar distances, though, be nearly as reachable by fast space probes, as Proxima, and nearly as favorably placed for SETI monitoring.
There could be exceptions, but as more flare observations are noted with red dwarf stars like Proxima b, it is increasingly apparent that the planets close enough to the red dwarfs to be in what we would call the "habitable zone" where liquid water can exist would get blasted by flares to the extent that as Ross 54 said, the atmosphere could be completely stripped away, and I would add possibly any oceans also. Therefore without water, it's hard to see how life as we know it could exist.
originally posted by: Soylent Green Is People
Life finds a way, and I would not be shocked to find out that life could exist on planets regularly flooded by solar flares.
I apparently haven't softened my prejudice as much as some people, because there are several problems with this magnetic field idea.
Roughly three quarters of the stars in the galaxy are red dwarfs, but planet searches have typically passed over these tiny faint stars because they were thought to be unfriendly to potential life forms.
But this prejudice has softened lately. Preliminary results from a dedicated research program have shown that planets around red dwarfs could be habitable if they can maintain a magnetic field for a few billion years.
So Mars is an example of what happens without a protective magnetic shield, and mars is much further from our sun than planets in the habitable zone are from their red dwarfs.
The fact that potentially habitable planets around a red dwarf are tidally locked implies they are rotating slowly around their axis. By the same physics that applies to stars, slow rotation will mean a weak magnetic field that could shut down completely.
This is what happened to Mars. It had a magnetic field 3.5 billion years ago, but when its liquid iron core solidified, the field turned off. Without this protective shield, the solar wind stripped away most of the planet's atmosphere and liquid water.
Possibly, but would such a magnetic shield be enough to protect against powerful flares as seen with proxima b? Proxima b may have no atmosphere and no ocean:
To avoid this fate around a red dwarf, Guinan speculates that a planet might need to be more massive than Earth. The large liquid iron core inside a super Earth (with a mass between 2 and 10 times Earth's) could perhaps maintain a magnetic field in spite of the slower rotation rate.
"Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water," [Meredith MacGregor, of the Carnegie Institution for Science] added.
For years, scientists thought that slowly rotating planets such as Proxima b could not support a strong magnetic field.
"However, more recent research has shown that planetary magnetic fields are actually supported by convection, a process by which hot material at the center of the core rises, cools and then returns," Barnes wrote. "Rotation helps, but Dr. Peter Driscoll and I recently calculated that convection is more than sufficient to maintain a strong magnetic field for billions of years on a tidally locked and tidally heated planet. Thus, it is entirely possible that Proxima b has a strong magnetic field and can deflect flares."
Planets that are close in tend to become tidally locked, always keeping the same face toward their star. Barnes noted that scientists once thought tidal locking didn't bode well for habitability; the star-facing side would be too hot for life, while the dark side would be too cold. But newer modeling work suggests that heat could be distributed more evenly via winds, making tidally locked worlds potentially habitable (if they have an atmosphere), he added.
Proxima b orbits very close to its star, which means that one side of it may permanently face the light source while the other remains dark and cold. Even in this scenario, the "hot" side maxed out at a comfortable 62 degrees Fahrenheit. (The cold side was about -190 degrees, so maybe that's not a great place to build our future colonies…)
originally posted by: Zelun
Great topic. Okay, I think that no, I don't think we should switch targets because even if all life had been extinguished there would still be traces of it to detect. Plus, the Earth has gotten baked(maybe, I'm making the assumption that CMEs are what causes magnetic field reversals) many MANY times and yet life persists. And it's the closest shot. I say we keep shooting for Proxima Centauri.