SH 2-188, also known as Simeis 22, is a planetary nebula located in the constellation Cassiopeia, about 850 light-years from Earth. Unlike most planetary nebulae, which are typically spherical or elliptical, SH 2-188 has an unusual shape. It appears as a crescent or semi-circular shell of glowing gas, with a faint tail-like structure extending behind it.
The nebula’s unique form is due to its interaction with the interstellar medium, the thin gas and dust that fill space. As the star at the center of SH 2-188 neared the end of its life, it expelled its outer layers into space, creating a shell of ionized gas. This shell has been distorted over time by the movement of the star through the surrounding interstellar medium, leading to its asymmetrical shape. It’s similar to how a boat moving through water creates waves that curve behind it.
The central star, which is now a white dwarf, was once similar to our Sun. When stars like this exhaust their fuel, they shed their outer layers, forming nebulae like SH 2-188. The star’s strong winds push against the surrounding material, creating the glowing arcs that we see. The nebula’s bright side is where the material is compressed by the movement, while the fainter regions trail behind.
Studying SH 2-188 helps astronomers understand the final stages of stellar evolution for stars similar to the Sun. It provides a glimpse into what might happen to our own solar system billions of years from now when the Sun reaches a similar stage. Observations of this nebula also offer insights into how stars interact with their surroundings, shaping the structure of our galaxy.
Capture Details:
Telescope: Celestron Nexstar 8se
Reducer/Flattener: Celestron .63x Reducer/Flattener
Filter: Optolong L-Pro Optolong L-Extreme
Camera: ZWO ASI294 MC Pro
Mount: Skywatcher EQM-35 Pro
Total Time: 4 hours 38 minutes
Capture Software: N.I.N.A.
Guiding: PHD2, ZWO asi120mm mini, ZWO OAG-L
Processed in: PixInsight
Additional details on Astrobin.com.