ASTRO: Sh2-115

Sharpless 115 is a very large emission nebula in the constellation of
Cygnus the Swan, about as far west of Deneb as the North American Nebula
is east of it. It is thought to be about 7,500 light years distant and
contain enough gas to make 4400 stars the size of our sun. It covers
several times the area of sky that I can fit into my field of view. The
nebula likely formed the star cluster Berkeley 90 toward the upper left
of center in my image. The illuminating star, the one whose ultraviolet
light causes the hydrogen gas to glow, is a member of the cluster and
one of the brightest and most massive stars known. It is classed as 06.
Find the cluster and note there are two brighter stars diagonally
across opposite sides of the cluster from 7 O'clock to 1 O'clock. The
one at 7 O'clock is the illuminating star. It is known as LS III +46
12. It appears dim compared to other stars in my image because most of
its light is emitted as ultra violet light. That is mostly blocked by
our atmosphere and what little does get through is blocked by my filters
since it is outside the visual range of our eyes. The nebula itself is
about 100 light years across. For a star to light up gas 50 light years
from it is quite a feat and shows how bright it really is! But for that
it will pay dearly. It will live only a couple million years before
going supernova while our sun with less than 1/10th the mass will live
over 10 billion years.

I've processed this for high contrast. Doing so caused much of the fain
nebulosity to be lost. The entire field shows nebulosity in the raw
data but if I processed it for that then most of the detail would be
lost. Computer monitors can reproduce only 255 brightness levels plus
black while the original data has about 4000 different levels. This
means I have to pick and choose what to show you and what to leave out
or allow to get lost due to low contrast. Just one of many decisions I
have to make when processing these images. This is why you will rarely
see two images of the same object that look the same. Each imager has
to decide what compromises best show the object the way the imager
want's it shown.

14" LX200R @ f/10, L=3x10+HA3x30', R=2x10'x3+HA3x30'*80%, G=2x10'x3,
B=2x10'x3+HA3x30'*20%, HA blended using lighten mode in all cases,
STL-11000XM, Paramount ME

Processing was made even more difficult because the color data was taken
on a much colder night than the L and Ha data. That meant it was taken
at a different image scale. Then the Blue was taken several hours after
Red and Green during which time the temperature fell even further again
changing the image scale. Thank goodness for Registar. It corrected
for all this and more.

Some have asked for a smaller image. I don't see why they can't shrink
it themselves but I've attached a half size version as well that is also
at higher compression.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".