Exploring the Lion Nebula: SH2-132
- Fabrice Lamidey
- Sep 15, 2024
- 3 min read
SH2-132, the Lion Nebula, is a fascinating object located in the constellation Cepheus. This emission nebula is a large HII region, composed of ionized hydrogen, and its brightness is the result of ionization by the surrounding massive stars. Although little known to the general public, SH2-132 offers a captivating opportunity for amateur and professional astrophotographers.

Location and main features
SH2-132 lies about 10,000 light-years from Earth in the outer region of our galaxy's Orion Arm. The nebula covers a relatively large region of the sky, marked by faint glows of ionized hydrogen and dark structures formed by clouds of interstellar dust.
Massive stars of spectral type O and B dominate this region. These stars emit a large amount of ultraviolet radiation that excites hydrogen atoms in the nebula, creating the characteristic reddish emission that can be observed in the H-alpha lines. These stars play a key role in the formation of new stars within the nebula.
Chemical composition and formation
Like many other HII nebulae, SH2-132 is composed mainly of hydrogen. However, the presence of other elements such as oxygen, sulfur and nitrogen is confirmed by spectroscopic analysis of the nebula's emissions. These elements are essential for understanding the processes of star formation and chemical evolution within these regions.
Observation and photography
This region is a relatively difficult target for amateur astronomers, due to the low brightness of its surface. Astrophotographers must use high-quality instruments and advanced techniques to obtain detailed images. Narrowband filters, such as those used to isolate H-alpha emission, are often employed to improve the visibility of the nebula.
Technical capture data
Equipment :
Imaging Telescope : Orion Newtonian 200/800mm 8" f/4 Astrograph
Imaging camera : QHYCCD QHY249M (CMOS)
Mount : Sky-Watcher EQ-6R Pro
Guide Telescope : Orion Newtonian 200/800mm 8" f/4 Astrograph
Guide camera : ZWO Optical ASI120 MM Mini (CMOS)
Filters :
Antlia H-alpha (4.5 nm)
Antlia OIII (4.5 nm)
Optolong SII (6.5 nm)
Accessories :
Automatic focuser: PrimaLuceLab Sesto Senso
Coma corrector: Baader Planetarium MPCC mkIII 2.00"
Filter wheel: QHYCCD CFW3 US
Off-axis corrector: ZWO Optical ZWO OAG
Processing software : PixInsight (Pleiades Astrophoto) 1.8
Capture conditions :
Seeing : 3 / 5
Transparency : 2 / 5
Sky darkness (Bortle scale) : 9
Ambient temperature : 25.0 ºC
Binning : 1x1
Gain : 1600
Average FWHM : 2.4 px
Images acquired :
Lights (H-alpha filter) : 133 x 180 sec
Lights (SII filter) : 133 x 180 sec
Lights (OIII filter) : 133 x 180 sec
Total integration time of lights : 19:57 hours
Image geometry :
Image size : 4,128 x 2,757 pixels
Image scale : 1.175 arcsec / pixel
Field of vision : 01º 20' 52"
RA Center : 22hr 16' 52"
DEC Center : 55º 54' 11"
Orientation : 310.1 degrees E of N
Image processing
Processing astronomical images requires powerful tools and technical expertise, especially when working with narrowband data. The SH2-132 image was processed using PixInsight , an image processing software known for its advanced image analysis and correction capabilities.
The approach taken for this image takes advantage of techniques taught by Adam Block , a pioneer in astrophotographic image processing. Adam Block is recognized for his innovative contributions to astrophotography, and his tutorials are followed by astrophotographers around the world. Block places particular emphasis on controlling noise and enhancing subtle details in deep-sky images.
One of Adam Block's new techniques used in the processing of this image is two-stage compositing, with separate colorization of the SII image and incorporation by addition (screening) into a HOO image. This technique allows the SII layer to be accentuated without polluting the darker parts.
The use of H-alpha, SII and OIII filters also helps to better isolate different areas of the nebula, giving a more contrasted and detailed image. Narrowband filtering helps to capture the specific emissions of the elements present in the nebula while minimizing the impact of light pollution, which is crucial in moderately dark sky conditions.
Conclusion
The SH2-132 nebula is a fascinating object for astronomers and astrophotographers. Its environment rich in massive stars, its complex gas and dust structures, and its emission regions make it a valuable target for deep-sky study and photography. With modern equipment and techniques, including advanced image processing tools such as those popularized by Adam Block, it is possible to capture the beauty and complexity of this nebula, contributing to a better understanding of stellar dynamics and star formation processes.
Sources
Block, Adam. Astrophotography Techniques . Adam Block Studios .
Pleiades Astrophoto, SL PixInsight Software .
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