The Lagoon Nebula in
H-Alpha + RGB
The Lagoon Nebula in Sagittarius
For comparison, click HERE to see
the pure RGB component. Click HERE to
see the pure H-Alpha component (no sharpening).
Discovered by Hodierna about 1654. The Lagoon Nebula Messier 8 (M8, NGC
6523) is one of the finest and brightest star-forming regions in the
sky. It is a giant cloud of interstellar matter which is currently
undergoing vivid star formation, and has already formed a considerable
cluster of young stars.
This object has been discovered by Giovanni Battista
Hodierna before 1654, and classified it as "nebulosa," i.e. of
intermediate brightness. It was independently noted as a "nebula"
by John Flamsteed about 1680.
According to Kenneth Glyn Jones, the Lagoon Nebula has an apparent
extension of 90x40 minutes of arc, which is 3 x 1 1/3 the apparent
diameter of the full moon, and corresponds to about 140x60 light years
if our distance of 5,200 light years should be correct, which is a bit
uncertain; newer sources have 4850 (Glyn Jones) to 6500, but David J.
Eichler gives the value of 5,200 light years (Eichler 1996).
One of the remarkable features of the Lagoon Nebula is the presence of
dark nebulae known as 'globules' which are collapsing protostellar
clouds with diameters of about 10,000 AU (Astronomical
Units). Some of the more conspicuous globules have been
cataloged in E.E. Barnard's catalog of dark nebulae.
Within the brightest part of the Lagoon Nebula, a remarkable feature
can be seen, which according to its shape is called the "Hourglass
Nebula" (see our detailed photos). This feature was discovered
by John Herschel and occurs in a region where a vivid star formation
process appears to take place currently; the bright emission is caused
by heavy excitation of very hot, young stars, the illuminator of the
hourglass is the hot star Herschel 36 (mag 9.5, spectral class O7).
Closely by this feature is the apparently brightest of the stars
associated with the Lagoon Nebula, 9 Sagittarii (mag 5.97, spectral
class O5), which surely contributes a lot of the high energy radiation
which excites the nebula to shine.
Scope: Planewave 12.5" CDK
Camera: Apogee U16M w Astrodon GenII H-Alpha filter
Mount: Paramount ME guided w Astrodon MMOAG and SBIG ST-402ME
6 x 15 min in H-Alpha
5 x 10 min in each of RGB
H-Alpha acquired with
CCDSoft5 and CCD-Commander
RGB acquired with TheSkyX and CCD-Commander
Reduction in Maxim
Alignment in RegiStar
Further processing in PS CC
Click on the image to see it 2x this resolution and to resize it in the
July 2014 (H-Alpha) and June 2015 (RGB)