Dark nebulae in zenith

09/2026
ASI2600MM Pro, 950mm, f/3.8,, 12.6h (R/G/B 3x2.0h, Lum: 6.5h)

Right next to the Iris Nebula we find a group of dark nebulae, like LDN1158. A dark nebula is a region of dense interstellar matter which obstructs stars in the background, appearing as a black spot.

Dark nebulae most commonly do not have clear borders but rather smooth edges, softly blending with the background stars. Of course there are exceptions like the horsehead nebula in constellation Orion.

On the left edge in this image you may spot a tiny curiosity:

This reflection nebula is named Gyulbudaghian's Nebel (GM 1-29) after the armenian astronomer Armen Gyul'budaghian who discovered it with Tigran Yu in 1977.

Observations show, that this nebula changes its appearance in rather short terms for astronomical objects, we are talking about years and even months.

These fast fluctuations in appearance are caused by the variable star PV Cephei inside the molecular cloud. Its intense radiation manages to poke a "hole" into the dense matter and so illuminates a small portion of the outer regions.

As the young star is most likely surrounded by a rotating aggregation disc, the emitted light is constantly changing and so is the appearance of the reflection nebula.