For over a week now, I’ve been teasing you with promises of a very pretty picture of a very pretty planet. Proxima Centauri is already known to have at least one planet, named Proxima b. Now a second planet, Proxima c, may have also been discovered.
So how do we know Proxima c is there? Well, we don’t. I would be an irresponsible science blogger if I didn’t make this 100% clear: astronomers do not know for certain if Proxima c exists. The evidence, as it currently stands, is highly circumstantial.
- First off, we have the possible detection of asteroid belts encircling Proxima Centauri. The presence of asteroid belts would imply the presence of planets, since it would take a planet’s gravity to keep the gaps between those asteroid belts clear.
- Second, as reported in this paper, we have the possible detection of a “compact source” of thermal emissions. There could be multiple explanations for this, but one possibility is a planet with a large, Saturn-like ring system.
- Lastly, according to this paper, Proxima Centauri is wobbling in place. That sort of wobbling in a star usually means a planet’s gravity is tugging on that star. Usually.
As I said, all this evidence is highly circumstantial. Proxima Centauri is known to have extremely violent solar flares, which may also explain why the star is so wobbly. And that compact source of thermal emissions could be lots of things other than a planetary ring system (it might even be an error in our data). And as for Proxima’s asteroid belts, we haven’t confirmed those exist yet. It would be premature to say anything about possible planets based on possible asteroids.
But as this article from Scientific American explains it, all this circumstantial evidence seems to be lining up in such a way that you have to go hmmm. If Proxima Centauri’s wobbles are caused by a planet, astronomers can make an educated guess about where that planet must be located. And that location lines up with that compact source of thermal emissions. And that compact source of thermal emissions is right where a planet would need to be to keep the gap between the asteroid belts clear. Coincidence? Well, maybe.
Again, this is highly circumstantial evidence. It will take a lot more observation and data analysis to determine whether or not Proxima c is really there.
But for a planet that may not exist, we know an awful lot about what Proxima c should be like. Based on Proxima Centauri’s wobbliness, we know Proxima c must be more massive than Earth, but less massive than Neptune. We also know it must be very cold. It’s a long way away from the habitable zone. Due to Proxima Centauri’s intense solar flare activity, we’d expect Proxima c to have some crazy bright aurorae. Oh, and as we already established, Proxima c would have a large, Saturn-like ring system.
In short, Proxima c sounds like it must be a very pretty planet.
If it exists. Which is still a pretty big if.
Quick programming note: I’m going to take a few days off from blogging. I’ll be away on a trip to visit family. My grandmother is turning 100 years old this weekend, so it’s going to be a party!
I’ll be back some time next week with updates about my book and an announcement about this year’s A to Z Challenge. See you soon!