Alpha Centauri / Proxima Centauri

[anemazoso]

Proxima orbits Alpha Centari AB. It is one part in a larger triple star system, which may explain why it hasn't been found to have a wobble.

http://en.wikipedia.org/wiki/Alpha_centauri :tiphat:

O-F Staff Note:
Posts moved to new thread here from Proxima Centauri add-on thread.

 

[JamesG]

Proxima isn't diffinitively part of Centauri AB. Its orbital period is so long that we haven't tracked its orbit or velocity enough to know if its truly captive, passing by, or just hanging out in the neihborhood. Either way, its far enough away to have its own system of planets.

Ought to model the whole Centauri cluster as a single addon. Between the plausable systems around each primary star, trips out to Proxima should be interesting as well.

 

[T.Neo]

There is probably plenty of "stuff" around Proxima Centauri. It is just low mass.

Asteroids, planetoids... perhaps even higher mass objects like terrestrial planets.

Our detection methods of extrasolar planets are rather crude at the moment. They tend to pick up massive objects close to their parent stars- like "hot jupiter" planets.

 

[JamesG]

There is probably plenty of "stuff" around Proxima Centauri. It is just low mass.

Asteroids, planetoids... perhaps even higher mass objects like terrestrial planets.

Yeah. But unfortunately as a variable "flare" star, its probably burned off most of the volitiles in its habitable zone, and any of its planets are pretty crispy.

 

[T.Neo]

Yeah. But unfortunately as a variable "flare" star, its probably burned off most of the volitiles in its habitable zone, and any of its planets are pretty crispy.

Plenty of the objects in our habitable zone are "crispy".

From what I can read, flares would not pose a problem to a habitable world if it had a magnetic field (possible even with the relatively slow tidelocked rotation). But such flares would probably be very dangerous to any organisms on the surface of such a planet.

 

[JamesG]

From what I can read, flares would not pose a problem to a habitable world if it had a magnetic field (possible even with the relatively slow tidelocked rotation). But such flares would probably be very dangerous to any organisms on the surface of such a planet.

No problem at all except for getting randomly fried by hard radiation and stellar plasma whenever your star has a spasm. :lol:

 

[RisingFury]

If the system had a lot of stuff in it, we would have either seen it, or seen its wobble.

I wouldn't make that assumption...

 

[JamesG]

If a red dwarf had a Jovian companion it would have oscillation and at our range we would be able to see it. That means little stuff, either not much, or lots of small bodies (< Earth) evenly spaced around it.

It would make a great refueling stop for the Sol to Alpha Centauri run (assuming you'd want to slow down for it), or as the hideout for space pirates/ evil bad guy, but the prospect of life or of even a habitable planet are unlikely.

 

[T.Neo]

If a red dwarf had a Jovian companion it would have oscillation and at our range we would be able to see it. That means little stuff, either not much, or lots of small bodies (< Earth) evenly spaced around it.

AFAIK, the radial velocity method doesn't work too well when the plane of the orbit is highly inclined to the observer.

The gas giant could also be orbiting far out. I think it would be detectable even then, unless it was seriously far out from the star. And I doubt planets that far from their stars would form easily.

I think asteroidal material at least is certain for Proxima as it is for most stars. There could still be an earthlike planet around Proxima (crude detection methods still have trouble detecting smaller mass planets), and a habitable planet might be even smaller then Earth- as long as it had a magnetic field and an atmosphere thick enough to circulate around the planet it could be habitable.

Proxima is also a variable star, which makes detection more difficult. Although I don't know how much attention it has been given, but it's also entirely possible that we simply haven't looked hard enough.

It would make a great refueling stop for the Sol to Alpha Centauri run (assuming you'd want to slow down for it), or as the hideout for space pirates/ evil bad guy, but the prospect of life or of even a habitable planet are unlikely.

I think that (at least at Sol-ACA distances) speed is more important then fuel mass. And adding a another deceleration and acceleration to the journey will increase risk.

As for piracy, I doubt it would be possible that way. If it could happen at all, it would probably happen in large systems with slower travelling traffic.

And life probably exists where there is abundant liquid water. Complex life is another matter, but I wouldn't be surprised if it developed some interesting traits to combat the flare problem.

 

[Izack]

And life probably exists where there is abundant liquid water. Complex life is another matter, but I wouldn't be surprised if it developed some interesting traits to combat the flare problem.

Yep. Domain Archaea could definitely do that. I wouldn't be surprised if it were possible to plant successful bacterial colonies on some other worlds, but that could be wishful thinking. At any rate, we shouldn't do that until we've invented monoliths, eh?

 

[T.Neo]

No no, I'm talking about complex life- stuff that could potentially resemble plants, animals, fungi etc.

Dealing with superflares would include taking shelter, closing up leaves and retracting limbs into resistant carapaces, and swimming to depths at which life would be safe from the radiation.

 

[JamesG]

I think you are underestimating how nasty a variable star is. A superflare (or even a regular flare) at Promima's habitable zone (less than half an AU) would ionize the atmosphere and boil off any free water present. Over time, they would leave any otherwise Earth-analog world barren and hard baked.

In such a case a Europa-analog might have more possibilities. Further away from the star, the surface would freeze, but assuming its large enough to have a long lasting molten core to heat the interior and enough water to form an ice shell over it. The flares might only temporarily melt some of the ice but still leave a protective coating. Life would develop on chemosynthesis alone.

Guess we won't know until we go there...

 

[T.Neo]

I think you are underestimating how nasty a variable star is. A superflare (or even a regular flare) at Promima's habitable zone (less than half an AU) would ionize the atmosphere and boil off any free water present. Over time, they would leave any otherwise Earth-analog world barren and hard baked.

Citation Needed.

In such a case a Europa-analog might have more possibilities. Further away from the star, the surface would freeze, but assuming its large enough to have a long lasting molten core to heat the interior and enough water to form an ice shell over it. The flares might only temporarily melt some of the ice but still leave a protective coating. Life would develop on chemosynthesis alone.

Perhaps, but that isn't "habitable" in the usual sense- life there could be solely cellular.

 

[JamesG]

Citation Needed.

You don't believe me? Or are you just to lazy to go look it up yourself?

Perhaps, but that isn't "habitable" in the usual sense- life there could be solely cellular.

Eh? Life is life. "habitable" is all in how you define it, and an aquatic environment is usually much more benign than space. For the majoirity of its existance on Earth, life here was nothing more than single celled organisms and algae slime.

 

[T.Neo]

You don't believe me? Or are you just to lazy to go look it up yourself?

No I do not, and yes I do know about flare stars, and I suspect you're just talking rubbish since from what I gather there are scientific arguments to counter your claims.

Eh? Life is life. "habitable" is all in how you define it, and an aquatic environment is usually much more benign than space. For the majoirity of its existance on Earth, life here was nothing more than single celled organisms and algae slime.

Habitable- pretty marbled terrestrial planet, with nice blue oceans and abundant life. At least a passing resemblance to Earth.

Europa and company belong in another catagory entirely. While they may contain habitable environments they have barren and lifeless surfaces.

Finding a Europa-like world is also nothing new, since we have several Europan bodies in our solar system. Ganymede, Callisto, Titan, Enceladus and Europa itself.

And while I see no reason as to why complex life should be limited to Earth, it would probably be at best less diverse in a Europan ocean.

EDIT:

And a lunar-sized body won't have enough internal heating to keep the subsurface ocean liquid without the tidal pull of a massive gas giant planet, that according to you cannot exist...

 

[JamesG]

I guess everyone is entitled to their own opinion.

 

[Urwumpe]

You don't believe me? Or are you just to lazy to go look it up yourself?

I think he is just having the same problem that I have: I can't find any source for your claims, you seem to just claim a lot of wild stuff.

---------- Post added at 10:33 AM ---------- Previous post was at 10:29 AM ----------

Yeah. But unfortunately as a variable "flare" star, its probably burned off most of the volitiles in its habitable zone, and any of its planets are pretty crispy.

Take for example this. You don't know what a flare star is, but you just claim about it:

http://en.wikipedia.org/wiki/Flare_star

http://arxiv.org/abs/astro-ph/0011153

 

[JamesG]

Are you looking for a formal thesis on it?

Ser'sly. Why should I spend my time educating you on such basic things when you can take a 20 second Google search and find the same information?

Do you argue that M class red dwarf stars are variable flare stars?
Do you argue that said stars would be highly gravitationally infuenced by gas-giant planets in their solar systems, making them readily detectable, especally at less than 5 ly?
Do you argue that the "habitable zone" (region where liquid water could exist on an Earth sized world) of a red dwarf is extremely close to the star's choronosphere?
Do you argue that those said conditions would make a "habitable planet" (as defined as an Earth-analog) highly unlikely in such a star sytem?
etc. etc. etc.

If no, then STFU because you are only making yourselves look like pedatic jerks.

 

[Urwumpe]

Are you looking for a formal thesis on it?

Would be great, if you have written one about your claims.

Ser'sly. Why should I spend my time educating you on such basic things when you can take a 20 second Google search and find the same information?

Because a 20 second search on Google Scholar does not support your claims at all.

Do you argue that M class red dwarf stars are variable flare stars?

Yes, because not all M class stars are flare stars. And not all flare stars are M class stars. And not a single flare star behaves like you claim.

Do you argue that said stars would be highly gravitationally infuenced by gas-giant planets in their solar systems, making them readily detectable, especally at less than 5 ly?

Sure, but it is also not me who claims that the star would have "burned all volatiles". And even a Earth sized planet would not cause any measurable wobble at such a short distance. Just calculate the orbit period of such a planet in the habitable zone and compare it to the detection limits for finding a "wobble".

Do you argue that the "habitable zone" (region where liquid water could exist on an Earth sized world) of a red dwarf is extremely close to the star's choronosphere?

It is Chromosphere. And it would be close, but the star is also much weaker in radiation. The habitable zone of a dwarf star is virtually not existent because of tidal locking, but the radiation is identical by the definition of habitable zone.

Do you argue that those said conditions would make a "habitable planet" (as defined as an Earth-analog) highly unlikely in such a star sytem?
etc. etc. etc.

Habitable is not Earth analog. That is the idiocy of using a sample size of one for drawing conclusions.

If no, then STFU because you are only making yourselves look like pedatic jerks.

That is written "pedantic"!

 

[JamesG]

I suspect you're just talking rubbish since from what I gather there are scientific arguments to counter your claims.

Eh? Actually I am purely speculating, since our factual knowledge of xenoplanetology literally fills a single page...

But YOU show me where I am wrong instead of simply arguing with me.

Habitable- pretty marbled terrestrial planet, with nice blue oceans and abundant life.

The fish people of some aquatic world in the universe would probably disagree with you.

Europa and company belong in another catagory entirely. While they may contain habitable environments they have barren and lifeless surfaces.

How is that at all relevant beyond the fact that you can't take a stroll in the sunshine?

Finding a Europa-like world is also nothing new, since we have several Europan bodies in our solar system. Ganymede, Callisto, Titan, Enceladus and Europa itself.

I was not arguing that a Europa like world was significant. I used the term "Europa-analog" hoping that it would give most readers a frame of reference for that type of environment without having to go into minusua.

And while I see no reason as to why complex life should be limited to Earth, it would probably be at best less diverse in a Europan ocean.

Which is completely unfounded speculation. Earth's aquatic life is as diverse as its dry land counterparts. There is no reason why it would not be quite diverse and sophisticated elsewhere.

And a lunar-sized body won't have enough internal heating to keep the subsurface ocean liquid without the tidal pull of a massive gas giant planet, that according to you cannot exist...

And who specified anything about a lunar-sized body? Oh you did, when you presumed I meant a literal "Europa" in a near orbit of Proxima Centauri...