3 ms·
Perhaps a dumb question, but if it’s focused, why is the star not a point, or small blob, but rather an enormous six-armed... star shape?
by rich_sasha 5y ago
Perhaps a dumb question, but if it’s focused, why is the star not a point, or small blob, but rather an enormous six-armed... star shape?
- theideaofcoffee 5y agoThese are diffraction spikes [0], caused by the support structures that carry the secondary mirror. The shape of the spikes are influenced by the arrangement of the struts. Here's a better researched answer of the same: [1] 0: https://en.wikipedia.org/wiki/Diffraction_spike https://en.wikipedia.org/wiki/Diffraction_spike 1: https://www.quora.com/What-will-the-diffraction-spikes-on-stars-imaged-by-the-James-Webb-Space-Telescope-look-like https://www.quora.com/What-will-the-diffraction-spikes-on-st...
- ianai 5y agoI wonder if this is an artifact we’ll only see for a few specific situations or something more overall.
- rich_sasha 5y agoRight - but these are enormous. This doesn't look anything like a clean image of a star. Is it just that it's so close / bright that the refraction spikes get so much in the way?
- ljp_206 5y agoI am seeing multiple stackexchange answers that suggest this is due to an intentional over exposure: https://space.stackexchange.com/questions/58624/jwst-aligned-test-image-march-16-2022-artifact-removal https://space.stackexchange.com/questions/58624/jwst-aligned...