IC 4603: Reflection
Nebula in Ophiuchius
From NASA’s Astronomy Picture of the
Day
Why does this starfield
photograph resemble an impressionistic
painting? The effect is created not by digital trickery but by
large amounts of interstellar
dust.
Dust, minute globs rich
in carbon and
similar in size to cigarette smoke, frequently
starts in the outer atmospheres of large, cool, young stars.
The dust is
dispersed as the star dies and grows as things stick to it in the interstellar medium. Dense
dust clouds are opaque to visible
light and can completely hide background stars.
For less dense clouds,
the capacity of dust to preferentially
reflect blue starlight becomes important, effectively blooming the
stars blue light out and marking the surrounding dust.
Nebular gas emissions,
typically brightest in red light, can
combine to form areas seemingly created on an artist's canvas.
Photographed
below is the central part of the nebula IC 4603 surrounding the
bright star SAO
184376 (actually 8th magnitude) which
mostly illuminates the blue reflection nebula.
IC 4603 can be seen
near the very bright star Antares (1st
magnitude) toward the constellation of Ophiuchus.
Image Credit & Copyright: Rolf Olsen