A Lion, an 'E' and some Dark Nebulae

The first eleven days of September offered me some excellent seeing conditions for a change and so I was very busy taking lots of subs for a number of new and interesting deep space objects. 

First up is Sh2-132 which is a relatively faint emission nebula about 10,000 lightyears distant in the constellation of Cepheus the King. Commonly known as the 'Lion Nebula' due to its shape (you can make out the head at the upper left, tail to the right, with four legs below). It features a conspicuous dark lane in the "head" section. 

This image was taken over five nights, with a total integration time of about 16 hours; 14 of those hours in narrowband and the remaining in RGB to capture the stars. 

Sh2-132 - Lion Nebula in SHORGB
William Optics GT102 (f/5.5) with ZWO ASI2600mm Camera
September 3, 6-9 2021

Next is LDN 688 & 694 (B142 & B143), collectively known as Barnard's 'E' nebula; gets it's name from the distinctive 'E' shape of the dark nebula that obscures the dense background of stars. The pair is also known as the Triple Cave Nebula. Although it appears that the two nebula are part of the same structure, they are, in fact, two distinct objects. It is our brain that wants to combine them into a familiar symbol, and so it appears as a single object.

LDN 688 & 694 in LRGB
William Optics GT102 (f/5.5) with ZWO ASI2600mm Camera
September 9 and 10, 2021

The bright star to the left is Gamma Aquilae (Tarazed). Gamma Aquilae is a relatively young star with an age of about 270 million years, estimated to be 3.5 times the mass of the Sun and about 92 times the Sun's radius. Shining at over 2100 times the luminosity of the Sun this K-type star glows with an orange hue. The image is a combination of twenty, 60sec exposures of RG and B with 40 x 60sec of luminance.

Finally, we have LDN 900 which is a Dark Nebula in the constellation of Cygnus.  It is approximately 8 arc-minutes (0.133 degrees) in size.  

LDN 900 in HaLRGB
William Optics GT102 (f/5.5) with ZWO ASI2600mm Camera
September 10 and 11, 2021

Dark nebulae are interstellar clouds that contain a very high concentration of dust. This allows them to scatter and absorb all incident optical light, making them completely opaque at visible wavelengths.  The nebula (centered in the image and running top to bottom) obscures the background of dust and ionized gas.

The blue regions are vdB 131 (upper) and vdB 132 (lower). These are both reflection nebulae, regions of what have been dark nebulae if not for the fact that the dust reflects the light from nearby bright stars that is not hot enough to ionize the cloud's hydrogen. This scattered light generally appears blue since the typical size of dust grains in the cloud are comparable to the wavelength of blue light.

This image is 5 hours of Hydrogen-alpha (Ha) and 4 hours of LRGB.