Chris Peterson wrote: ↑
Mon Oct 26, 2020 4:55 am
Ann wrote: ↑
Mon Oct 26, 2020 4:46 am
I've recently talked about yellow reflection nebulas. Well, the Ghost Nebula is obviously another jaundiced cloud complex in the cosmos.
I'll leave the discussion of ghosts to other members of Starship Asterisk*.
Just brown dust reflecting white light. What we generally see with dusty molecular clouds.
Brown dust reflecting white light usually creates a blue reflection nebula. Our Sun, which is white, can have its colors separated into blue and yellow hues by gas, dust and droplets of water in the Earth's atmosphere.
IC 4592: The Blue Horsehead Reflection Nebula.
Image Credit & Copyright: Mario Cogo
A very interesting patch of nebulas in the sky can be seen in and around blur reflection IC 4592. The blue color of this nebula is due to dust particles scattering light from the intrinsically very blue star Nu Scorpii, spectral type B2IV. I have marked this nebula with the number 1 in the image at left.
Yes, but there is also another, much smaller blue reflection nebula near the large reflection nebula surrounding Nu Scorpii. I have marked this other blue nebula with the number 3. It surrounds a small group of stars, of which two are visible. These stars are not at all as hot as Nu Scorpii, as they belong to spectral classes B9V and A0V. Therefore they don't produce nearly as much blue light as Nu Scorpii, but still enough for dust particles in the vicinity to scatter some of their light into a blue reflection nebula, called IC 4601.
Yes, but there is a third reflection nebula in this picture, a mildly yellow one. I have marked it with the number 2. This patch of light has a proper nebula designation, van den Bergh 101, so it is a reflection nebula all right. It surrounds a K-type star, which is yellower than the Sun, so the nebula is non-blue and in fact mildly yellow. It is the light from this K-type star that has been scattered by dust particles in the vicinity and produced the nebula.
The Blue Horsehead (top right), Rho Ophiuchi and Antares (center right)
and the yellowish plane of the Milky Way (left). Photo: Mohammad Rahimi.
We may also note that some of the dust forming the shape of the Blue Horsehead nebula is indeed just brown, yet it appears to be slightly lit up. What is the light source for this faintly illuminated brown dust? Perhaps scattered light from the mostly yellowish disk of the Milky Way itself?
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