by Ann » Wed Nov 09, 2016 6:09 am
Oldironsides wrote:Forgive me for the intrusion but I am more of a visitor than a commentor to APOD. I think I have raised the question once before but this image and the discussion about the diffraction spikes has refreshed my memory. The image explanation says it spans a distance of 17 light years but there seems to be an awful lot of stars in this cluster and while the diffraction spikes only add to the clutter I am wondering how far apart these stars are to one another? While the span, left to right may be only 17 light years, the photographic compression (foreground to background) could still be much more than that. But still these stars seem close enough to fit inside our Solar System. Any guess how far apart they are?
According to the caption, the entire image spans about 17 light-years, but the central concentration of stars is much smaller. Could the densest part of the central core be, perhaps, 3 light-years?
To estimate how close the stars are to one another, we need to know how many stars reside in a given volume. I have been unable to find an estimate of the number of stars in NGC 3603. If we include low-mass stars, however, I would think we must be talking about several thousand stars, quite possibly more than 10,000 stars for the entire cluster, and almost certainly no less than a thousand stars for the central compact core.
Would these stars fit inside our own solar system? Well, bearing in mind that the outer part of the solar system, the Oort Cloud, is supposed to extend a light-year or so from the Sun, then absolutely, there would have to be many stars in NGC 3603 within the volume of the Oort Cloud. How about the Kuiper Belt? Pluto is supposedly the largest of the Kuiper Belt objects, and its average distance to the Sun is 39.5 AU, or 39.5 times the distance from the Sun to the Earth. Yes, I think there might well be several stars within a radius of 39.5 AU in a cluster like NGC 3603, and that might include stars that are not binary or multiple stars
per se, but just stars that are zipping past one another at high speeds.
Ann
[quote="Oldironsides"]Forgive me for the intrusion but I am more of a visitor than a commentor to APOD. I think I have raised the question once before but this image and the discussion about the diffraction spikes has refreshed my memory. The image explanation says it spans a distance of 17 light years but there seems to be an awful lot of stars in this cluster and while the diffraction spikes only add to the clutter I am wondering how far apart these stars are to one another? While the span, left to right may be [u][i]only[/i][/u] 17 light years, the photographic compression (foreground to background) could still be much more than that. But still these stars seem close enough to fit inside our Solar System. Any guess how far apart they are?[/quote]
According to the caption, the entire image spans about 17 light-years, but the central concentration of stars is much smaller. Could the densest part of the central core be, perhaps, 3 light-years?
To estimate how close the stars are to one another, we need to know how many stars reside in a given volume. I have been unable to find an estimate of the number of stars in NGC 3603. If we include low-mass stars, however, I would think we must be talking about several thousand stars, quite possibly more than 10,000 stars for the entire cluster, and almost certainly no less than a thousand stars for the central compact core.
Would these stars fit inside our own solar system? Well, bearing in mind that the outer part of the solar system, the Oort Cloud, is supposed to extend a light-year or so from the Sun, then absolutely, there would have to be many stars in NGC 3603 within the volume of the Oort Cloud. How about the Kuiper Belt? Pluto is supposedly the largest of the Kuiper Belt objects, and its average distance to the Sun is 39.5 AU, or 39.5 times the distance from the Sun to the Earth. Yes, I think there might well be several stars within a radius of 39.5 AU in a cluster like NGC 3603, and that might include stars that are not binary or multiple stars [i]per se[/i], but just stars that are zipping past one another at high speeds.
Ann