Does twinklingdepends on the star or the distance?

[Astro.padma]

I am here with another silly doubt...Is twinkling because of the star or the distance? What matters here?

For example...If the stars Sirius and Proxima Centauri were at the same distance from earth, which star would twinkle more?

As they are at the same distance, would they twinkle equally?


Um...am sorry if my questions are a bit silly but please try to answer them as I am really a beginner :)

 

[Subductionzon]

As far as your naked eye can determine all stars are point sources of light and twinkling is due to atmospheric disturbances of the light path. A brighter star would probably seem to twinkle more only because it stands out from the background better. And the brightness I am referring to is the brightness as perceived here, not the absolute brightness of a star. Planets don't twinkle because they subtend a very small, but noticeable arc. The atmospheric disturbances are not great enough to make a planet twinkle.

 

[Astro.padma]

A brighter star would probably seem to twinkle more only because it stands out from the background better. And the brightness I am referring to is the brightness as perceived here, not the absolute brightness of a star. .

Sir...then is it that both the Proxima and Sirius twinkle equally as they are assumed to be at same distance and thus having same background...am I right?

And what about the absolute brightness of a star? Wouldnt it contribute anything to our present context?

 

[cjl]

It has nothing to do with the distance, only the visible (apparent) brightness. All stars are far enough away that they effectively act as point sources, so the distance doesn't actually matter.

 

[Astro.padma]

then do they twinkle equally?

 

[Subductionzon]

If they are the same apparent brightness yes. And I am sure that an astronomer could come up with the correct term, but when I say apparent brightness I mean the brightness that your eye perceives, not the brightness at the star itself.

 

[Astro.padma]

Subductionzon... what do u mean by same apparent brightness, when it is the single person viewing both the Proxima and Sirius, at same time?

I mean...the eye would perceive, same brightness, right?

 

[Astro.padma]

umm :( aint understanding...which answer is right? Is it yes or no?

What I understand here is...One says that They don't twinkle equally because both of them are at almost large distances so only their individual brightness matters.

and the other says that Yes, they do twinkle equally because they would be of same background and there wouldn't be any atmospheric disturbances.


Am I right or gone wrong somewhere...Excuse me if it is but someone please get me some clarification:)

 

[Subductionzon]

There are two ways to talk about how bright a star is. The first is to talk of its "magnitude" that is how bright it appears here on Earth. The second would be to talk about how bright it is from some set distance from the star.

For twinkling we are using the first definition of how bright a star is. So yes if both stars are of the same magnitude, that is they appear to be the same brightness here on Earth, then they will twinkle the same amount. I hope that answers your question. We really don't car how bright they are at the source, only how bright they appear here on the Earth.

 

[Astro.padma]

For twinkling we are using the first definition of how bright a star is. So yes if both stars are of the same magnitude, that is they appear to be the same brightness here on Earth, then they will twinkle the same amount. I hope that answers your question. QUOTE]

No...I think I've confused you ... See, they are Proxima and Sirius of magnitudes 11.05 and (-1.46) , respectively.They are at different distances from the earth. My question is if they are at same distance, would they twinkle equally?

Here, in this case, both Proxima and Sirius are entirely different in their magnitudes...but they are at same distance...now would they twinkle equally?

 

[Subductionzon]

The distance to all stars is so huge that distance does not matter. All stars that you can see with your eye are effectively point sources. So they all twinkle. If they are of the same magnitude they will twinkle the same regardless of how far away the star is. Whether a brighter or dimmer star "twinkles" more would be a matter of opinion. But if you had two stars that were equally bright as seen from Earth but one was one thousand times bigger than the other and much further away so there magnitudes here were equal they would twinkle in the same fashion.

 

[snowmonkey12]

Twinkling is caused by the Earths atmosphere so the perceived twinklyness(?? :S) would probably depend on the apparent magnitude, as it would be easier to see the twinkling of a bright star, and which was seen through a more distorting atmosphere

 

[Astro.padma]

Sorry... :( any other?