by Ann » Wed Oct 17, 2012 11:58 pm
dougettinger wrote:I see no evidence of a binary companion. And I see no reason how such an object can cause a spiral of such dimensions.
The outer ring is actually a dis-connected circle; the inner regions show more spiral characteristics. The configuration of the nebula is indicative of how the star is ejecting material from its surface. The first ejection was very fast, much faster than the rotational speed of the star. Hence, a very distinct equatorial circular outer ring of material was formed. Later ejections became less powerful, but still created less distinct circular rings of material. The earliest ejections are much less powerful and the ejecta velocities are much closer to the rotational speed of the star thereby creating the very distinct inner spiral that is being discussed.
That is my "take" on this very interesting red giant nebula,
Doug
The reason why you don't see the companion is likely because the companion is so very much fainter than R Sculptoris itself. Remember that R Sculptoris is likely at a late evolutionary phase where it is extremely bright for its mass. The companion, which is likely less massive than R Sculptoris, is probably unevolved and very much less bright. I have read somewhere that when the Sun becomes a red giant, it will undergo phases where it is briefly at least a thousand times brighter than it is now.
Also note that this picture was taken by a telescope which detects wavelengths that are much longer than visible light. A cool star like R Sculptoris will show up well here, but an unevolved companion whose temperature is comparable to that of, say, the present-day Sun, will likely be undetectable in an image like this unless special processing is made to bring it out.
But even if the companion is certainly very much less bright than R Sculptoris, it doesn't have to be much less massive. It could very well strongly affect and shape the outflows from R Sculptoris.
Ann
[quote="dougettinger"]I see no evidence of a binary companion. And I see no reason how such an object can cause a spiral of such dimensions.
The outer ring is actually a dis-connected circle; the inner regions show more spiral characteristics. The configuration of the nebula is indicative of how the star is ejecting material from its surface. The first ejection was very fast, much faster than the rotational speed of the star. Hence, a very distinct equatorial circular outer ring of material was formed. Later ejections became less powerful, but still created less distinct circular rings of material. The earliest ejections are much less powerful and the ejecta velocities are much closer to the rotational speed of the star thereby creating the very distinct inner spiral that is being discussed.
That is my "take" on this very interesting red giant nebula,
Doug[/quote]
The reason why you don't see the companion is likely because the companion is so very much fainter than R Sculptoris itself. Remember that R Sculptoris is likely at a late evolutionary phase where it is extremely bright for its mass. The companion, which is likely less massive than R Sculptoris, is probably unevolved and very much less bright. I have read somewhere that when the Sun becomes a red giant, it will undergo phases where it is briefly at least a thousand times brighter than it is now.
Also note that this picture was taken by a telescope which detects wavelengths that are much longer than visible light. A cool star like R Sculptoris will show up well here, but an unevolved companion whose temperature is comparable to that of, say, the present-day Sun, will likely be undetectable in an image like this unless special processing is made to bring it out.
But even if the companion is certainly very much less bright than R Sculptoris, it doesn't have to be much less massive. It could very well strongly affect and shape the outflows from R Sculptoris.
Ann