5 ms·
https://en.wikipedia.org/wiki/Limb_darkening https://en.wikipedia.org/wiki/Limb_darkening
by Kikawala 5y ago
https://en.wikipedia.org/wiki/Limb_darkening https://en.wikipedia.org/wiki/Limb_darkening
- ben_w 5y agoAnd the opposite effect, as shown in my first link?
- gattr 5y agoIn that link it is due to the wavelength used (extreme UV, which shows only active regions as bright, and the prominence layer surrounding the limb.) However, in many amateur pictures taken in the H-alpha wavelength (like in TFA), the artistic choices come into play, as you said. In the Simon's first image the prominence layer (just outside the limb) is shown as-is (positive), while the disc interior is shown inverted (a negative; note e.g. how the sunspots became white). This is done to get a somewhat more "3D look". In a normal, non-inverted image, the mottles and filaments show up as dark features on a bright background, while inverting may make them look more "natural" (to some) - sometimes downright "casting shadows" (a solar filament often has a brightening around its base - which becomes dark after inversion). Source: I'm the ImPPG's author (and enjoy solar astrophotography myself).
- ben_w 5y agoThanks! I love detailed answers like this :)
- Helmut10001 5y agoJust a side note, the opposide effect is can be achieved with a phenomenon called Subsurface Scattering (also used in 3d-cg). This has nothing to do with stars, though - unless a star exists that is translucent.
- robbedpeter 5y agoBoson stars! https://www.sciencealert.com/there-could-be-transparent-stars-made-of-bosons-masquerading-as-black-holes https://www.sciencealert.com/there-could-be-transparent-star... https://en.wikipedia.org/wiki/Exotic_star https://en.wikipedia.org/wiki/Exotic_star