Strange alignment of orange galaxy on right edge
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by dtrucken
ok, i know it can't be.... upper right edge. orange galaxy, then two dots on left at 9 oclock, two at 5 oclock. (don't count the blue one)
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by Tom_Collett scientist
Everything there is the same color, which tends to imply a group of galaxies all at the same redshift. I don't think the postioin of the small guys is plausible for a lensed high redshift quasar either.
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by AlexandredOr
Facetious hazard... 😉
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by dtrucken
thanks Tom for the explanation. So the idea here is that the center object should be a slightly different color, because the ones that "get lensed" are further away, and thus color-shifted even more? Would that imply that they would be slightly more red, or more blue? (My little mind is still trying to grasp this whole "curved space-time" idea on a more than intellectual level.)
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by Tom_Collett scientist
So it turns out that redshifting doesn't actually make things look redder - the whole spectrum shifts red-ward , but that brings UV light in to replace the blue light that's become red. The color (difference in observed red light and observed blue light) needn't change with redshift, and can even get bluer in some cases!
Color is more a measure of temperature and age. (Hot young stars are blue (and UV), cool old stars are red), so if you have similar color objects, there is a suspicion that they are similar ages, and so probably associated with each other. The association isn't a certainty, but it's more likely than lensing in this case.
The best thing to do in a situation like this is raise a discussion in talk 😃
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by dtrucken
thanks for the explanation! so, in general, the red stars will be older, and by implication, (because the universe is expanding) further away. not always the case, but a generalization?
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