by Ann » Wed Feb 14, 2018 5:36 am
Interesting picture, very suitable for Valentine's Day.
I like the picture, but I would like to know more about how it was made. A "pure" RGB portrait of the Heart Nebula would probably make it look very red, like
this picture. An HαOIIISII narrowband image would make the nebula look flamboyantly blue, green, yellow and orange-brown, like
this picture.
Well, perhaps today's APOD is a relatively normal RGB picture with a little extra blue for contrast.
APOD Robot wrote:
The red glow and the larger shape are all created by a small group of stars near the nebula's center.
Well, yes. But the wording makes it sound as if the hot stars emit copious amounts of red light themselves. Actually, they
do emit copious amounts of red light, but they emit a lot more blue light and
very much more ultraviolet light. It is all the ultraviolet light that ionizes nearby hydrogen atoms, knocking their one electron into a higher orbit, which then causes the electron to emit red light as it drops back into its normal orbit again.
Ann
Interesting picture, very suitable for Valentine's Day.
I like the picture, but I would like to know more about how it was made. A "pure" RGB portrait of the Heart Nebula would probably make it look very red, like [url=https://cdn.psychologytoday.com/sites/default/files/styles/image-article_inline_full/public/blogs/105364/2015/01/168736-174029_0.jpg?itok=rjAQL48a]this picture[/url]. An HαOIIISII narrowband image would make the nebula look flamboyantly blue, green, yellow and orange-brown, like [url=http://kreisler.zenfolio.com/img/s/v-3/p1259838890-3.jpg]this picture[/url].
Well, perhaps today's APOD is a relatively normal RGB picture with a little extra blue for contrast.
[quote]APOD Robot wrote:
The red glow and the larger shape are all created by a small group of stars near the nebula's center.[/quote]
Well, yes. But the wording makes it sound as if the hot stars emit copious amounts of red light themselves. Actually, they [b][i]do[/i][/b] emit copious amounts of red light, but they emit a lot more blue light and [b][i]very[/i][/b] much more ultraviolet light. It is all the ultraviolet light that ionizes nearby hydrogen atoms, knocking their one electron into a higher orbit, which then causes the electron to emit red light as it drops back into its normal orbit again.
Ann