the_fungible_man t1_irv8h4x wrote
The chances are 0.
The nearest star to the Sun, Proxima Centauri, is tiny, with about 12% of the mass of the Sun. The minimum mass for a star to sustain fusion in its core is ~8-9% of a solar mass, so this is a really small, cool, dim red star. And yet, from Earth, this star has a visual magnitude of 11, which is quite bright for a star less than 0.2% as luminous as the Sun.
Proxima Centauri could hardly be any smaller or dimmer and still be a star, and yet it can be easily observed with modest equipment. Any nearer star likewise would have already been detected.
FluffyTid t1_irve9ba wrote
I was going to say chances are 100 because Alpha Centauri is not the closest star. But your answer is a lot more on point
[deleted] OP t1_irvujwe wrote
[removed]
frenchtoaster t1_irvxkm0 wrote
The question said closest star to Sol, not to Earth. Unless you mean like the person nearest to you is you at distance zero.
greyl t1_irw30em wrote
No, he's saying the closest star to Sol isn't Alpha Centauri it's Proxima Centauri.
It's pretty confusing though because "Alpha Centauri" is a 3 star system and the individual stars within Alpha Centauri are named Alpha Centauri A, Alpha Centauri B, and Proxima Centauri.
Aenyn t1_irw4gti wrote
So in a few hundred thousand years it will be Alpha Centauri AB that will be the closest stars to our system?
skibble t1_irw6r18 wrote
I'm confused. AB are a binary, orbiting their center of mass. Proxima is closest to Sol. How is Proxima gravitationally related to AB? If she were orbiting them, wouldn't she sometimes be closest and sometimes be furthest?
hilburn t1_irw7atx wrote
Proxima orbits AB with a period of ~550,000 years.
So the "sometimes" is a while, and includes for as long as we've been measuring things
[deleted] OP t1_irw8s0w wrote
[removed]
Oknight t1_irw7odq wrote
The orbital period of Proxima makes it the closest star to Earth for a much longer period than human beings generally care about. Eventually even the Alpha Centauri system including Proxima won't be the closest stars to Earth and the time frame for that isn't all that much larger than a Proxima "year". In less than 3 Proxima years Gliese 710 will pass only 90 Light Days from Sol.
NavierIsStoked t1_irwg9b5 wrote
>90 light days from Sol
That seems to be well within the Oort Cloud. I would assume that could cause some objects to get directed into to the solar system. Hopefully we will still be around to care.
Reading the wiki about 710, it seems there is an 86% chance of going through the Oort Cloud. I noticed it didn’t say anything about what 710 would be dragging with it. I assume all stars have some kind of Oort Cloud.
[deleted] OP t1_irvzjnq wrote
[removed]
mfb- t1_irvnot8 wrote
Various surveys looked for all objects down to magnitude ~20, that's an equivalent of Proxima Centauri but ~4000 times dimmer, or 250 light years away. Vera Rubin will improve that by more than a factor 100 in brightness.
echoAwooo t1_irw3nad wrote
The Centauri Solar Cluster has a high visual magnitude because it's a triple system where Proxima is the smallest of the three suns orbiting the barycenter. Proxima contributes very little light to that high visual magnitude, it's all mostly αCenA and αCenB, the other two stars in the system. A and B both together make it the third brightest star in the sky.
TheOriginal_Dka13 t1_irw65mg wrote
Theoretically cohldnt there could be a dim star like proxima centauri, but covered by a cloud of dust so we cannot see it?
Krail t1_irw90m5 wrote
What are th odds that, say, a brown dwarf could be lurking close, undetected?
[deleted] OP t1_irvdb2n wrote
[deleted]
[deleted] OP t1_irwaz91 wrote
[removed]
[deleted] OP t1_irvokdr wrote
[removed]
qutronix t1_irvq9iu wrote
If there was something with a dyson spehere we would have seen it. They look pretty obvious, a body invisible in visible light, yet shining in infra red.
[deleted] OP t1_irvvudw wrote
[removed]
AndyTheSane t1_irvysht wrote
Where would they put the heat?
[deleted] OP t1_irw0vli wrote
[removed]
mfb- t1_irw4nbr wrote
Computation doesn't destroy the energy. If your system is fed by a Sun-like star you still get a Sun-like excess in radiation. At 6 K or 1/1000 of the Sun's surface temperature you need 1000^4 times the surface area, or a radius of 0.07 light years. The system would show up as an absurdly bright (~20 times the background where we look for 0.001% deviations) and relatively big spot in CMB surveys. You can change the temperature but the result won't change, you can't hide a radiation excess that large close to us. Probably not even 0.001% of it.
throwaway1point1 t1_irw3jl0 wrote
I've always wondered about this tho... I have enough knowledge of physics to get really confused, but not enough to understand how exactly it gets there.
There's still always heat, right? Using the energy for computation doesn't mean you're not still retaining the entire energy output of the sun inside a shell. You use the heat... But at the end you still have the heat.
Is it just that theoretically the outer shells are so big that it is simply diffusing the heat of the star across a vastly (vastly) larger area?
abbersz t1_irw6ljs wrote
>The outermost layers should be at the background temperature and effectively invisible via infrared, unless they occlude something behind them.
This outermost shell would be the least powerful but also the most materially expensive to construct, due to size.
It is incredibly unlikely that a culture would want to absorb 100% of a suns energy using this method, rather than losing a few shells and not having to spend the exponentially increasing cost of new shells. Only way this works is if a species has figured out how to not have to worry about the laws of physics, in which case, why are they bothering with locating it around a specific star in the first place?
[deleted] OP t1_irvywsl wrote
[removed]
[deleted] OP t1_irwjbpd wrote
[removed]
Viewing a single comment thread. View all comments