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[Mentor Note -- Discussion spun off from the main JWST thread]
Yes, the apparent hexagonal shape of that star is due to the diffraction within the telescope optics (optical filter characteristics may also have played a role).
For clarity, we're talking about this star:
They are (images from the same telescope optics, that is). You can even see it in the main subject star in the original image:
Ignore the dust rings for a moment, and concentrate on the central star. Its apparent shape is a hexagon, just like the other star (same size even). It's just that it's so much brighter that all the color detail is saturated (blown highlights), so it just looks like a white hexagon.
You might not see the hexagon shape in the other stars because they are relatively dimmer. With the dimmer stars, the outer 6 hexagonal components more easily blend into the background. But they're technically still there. You might be able to spot more if you look closely.
Much of what gets saturated and what doesn't, is not only dependent on the telescope's optics hardware (which may include the optical filters used) and exposure characteristics, but also on the image processing details, such as how the histogram was stretched before the final image shown.
pinball1970 said:What is this top right? It looks very symmetrical in shape and colour, just an optical effect from the telescope like diffraction spikes?
Yes, the apparent hexagonal shape of that star is due to the diffraction within the telescope optics (optical filter characteristics may also have played a role).
For clarity, we're talking about this star:
sophiecentaur said:But why aren’t all (bright) star images like it?
They are (images from the same telescope optics, that is). You can even see it in the main subject star in the original image:
Ignore the dust rings for a moment, and concentrate on the central star. Its apparent shape is a hexagon, just like the other star (same size even). It's just that it's so much brighter that all the color detail is saturated (blown highlights), so it just looks like a white hexagon.
You might not see the hexagon shape in the other stars because they are relatively dimmer. With the dimmer stars, the outer 6 hexagonal components more easily blend into the background. But they're technically still there. You might be able to spot more if you look closely.
Much of what gets saturated and what doesn't, is not only dependent on the telescope's optics hardware (which may include the optical filters used) and exposure characteristics, but also on the image processing details, such as how the histogram was stretched before the final image shown.
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