Espectro das cores - Filtros H-alfa, O III e S II

[jsmoraes]

Em Astrofotos se fala muito em filtros H alfa, O 3 e S 2, linhas de emissão de hydrogen (H-alfa, 656 nm), oxygen (OIII, 501 nm), sulfur (SII, 672nm)

Cor - Comprimento de onda (nm)

Violeta - 390 – 450

Anil - 450 – 455

Azul - 455 – 492

Verde - 492 – 577

Amarelo - 577 – 597

Alaranjado - 597 – 522

Vermelho - 622 – 780

Ou seja:

H alfa, vermelho-rosa

Enxofre 2, vermelho

Oxigenio 3, verde

E uma explicação dos motivos da paleta de Hubble (de uma foto do Pilar da Criação):

The final image depicts red light from hydrogen atoms as green, red light from sulfur ions (sulfur atoms with one electron removed) as red, and green light from doubly-ionized oxygen (oxygen atoms with two electrons missing) as blue.
These color reassignments enhance the level of detail visible in the image, because otherwise the red light from hydrogen and that from sulfur would be hard to tell apart.
In the final image, the blue-green haze indicates light from hydrogen and oxygen surrounding the dark columns. The columns display reddish highlights identifying light from sulfur.