Do You Think There Are Planets Around Alpha Centauri?

[caballerodiez]

So far, we have only discovered one exoplanet in the triple star system of Alpha Centauri: Proxima b.

I think it is highly likely that there are more exoplanets in that system.

What are your thoughts?

I think this live streaming of Alpha Centauri might motivate you: http://www.youtube.com/watch?v=PCllBPRrHUE

[HebaruSan]

Considering the sheer number of chunks of rock floating around our sun, I have trouble imagining a star whose formation is so "clean" that all of that stuff somehow makes its way to the central body.

... I guess maybe if the source matter had exactly zero angular momentum?

Edited April 9, 2020 by HebaruSan

[Spacescifi]

2 hours ago, caballerodiez said:

So far, we have only discovered one exoplanet in the triple star system of Alpha Centauri: Proxima b.

I think it is highly likely that there are more exoplanets in that system.

What are your thoughts?

I think this live streaming of Alpha Centauri might motivate you: http://www.youtube.com/watch?v=PCllBPRrHUE

 

Yes. Planets are fairly common... barren, lifeless rocky planets and planets full of gas.

Earth? She's one of a kind.

Are we the only intelligent life in the universe?

No. But it won't be what popular science expects it to be.

 

Edited April 10, 2020 by Spacescifi

[Nuke]

habitable is not so much a black and white thing as a shade of grey, with very few planets completely in the black and even earth itself not being completely white. right kind of power supplies and you can make any of them useful to a spacefaring civilization.

[Geonovast]

Moved to Science & Spaceflight

[Spaceception]

Well, we did find at least one candidate a while back around Alpha Centauri B, so I think there must be something there. Though how many, or how far out they could orbit, I don't know. We really should get more exoplanet telescopes up to look.

[wafflemoder]

It is quite probable that there are additional planets in the system. Here's my somewhat lengthy, but hopefully comprehensive summary on what types of worlds could be where in the system based on our current understanding of planetary science. For reference, these are the two types of planetary orbits in multiplanetary systems. S-type orbits go around a singular star, and P-type orbits go around multiple stars.

There are four main regions where planets could reside in the Alpha Cen. + Proxima Cen. ternary system: S-type orbits around Proxima (C), S-type orbits around A, S-type orbits around B, and P-type orbits around both A and B, but not Proxima.

Planets around Proxima (Alpha Cen C): There are currently two planets known to orbit Proxima: proxima b, and proxima c. Based on recent measurements of the inclination of c, the two planets likely mass 2.1 and 12 Earth masses respectively. As current detection limits are fairly low, and planets have already been found here, it is quite probable that there are additional bodies in the system.

Planets around Alpha Cen A: It's certainly possible for there to be planets around A, but there are some complications. Alpha Cen A and B are separated by 17.6 AU on average (varying between 11.2 and 35.6 AU). While planets orbiting up to 2.8 AU away would be stable, it is unclear if planets could have formed in this region. Several planets have been found around single stars in multistar systems, but few as close together as Alpha Cen A and B. OGLE-2013-BLG-0341L B is currently the record holder for tightest binary with an S-type planet, and is separated from its companion by somewhere between 11 and 17 AU. This is very similar to Alpha Cen, but the stars in the OGLE-2013-BLG-0341L system are both red dwarfs, where planets would form much closer in, so its still unclear if planets could have formed around Alpha Cen A. There is some evidence for dust around A and/or B, so its certainly possible that planets could exist there.

Planets around Alpha Cen B: A very similar case to A, certainly possible, but the situation is made complicated by the AB binary pair. Unlike A, there is an unconfirmed exoplanet around Alpha Cen B. Bc, if confirmed, would be a lava world about the same size as Earth. Alpha Cen Bb was found to be cause by data artefacts in 2015, and so is extremely unlikely to be present. With unconfirmed planets and possible dust, it is possible that one or more planets could be present.

Planets in P-type orbits around both Alpha Cen A and B: This is possible, but less likely than planets around either A or B. There are numerous binary systems with planets in P-type orbits, but none have been found in systems with stars as far apart as Alpha Cen A and B. The current record holder is FW Tauri AB b, orbiting stars separated by 11 AU, which is only two-thirds the average separation in Alpha Cen. It is also unclear if FW Tauri AB b is a high mass planet, brown dwarf, or low mass star. Even if no planets were able to form in P-type orbits around A and B, it is possible that some worlds were flung out from A or B into orbit around the pair.

Cool Info, but what do I actually think? I'd guess there are few more planets orbiting proxima. I'd also guess that there are a several planets in S-type orbits around A and B, but wouldn't be too surprised if this wasn't the case. I'd guess there aren't any planets larger than Earth orbiting A and B in a P-type orbit, but wouldn't be shocked if one was found eventually. I would however guess that there are several circumbinary dwarf planets around the pair. 

Hope this helps give ideas and clears up more confusion than it causes.