IC 4628, the Prawn in Scorpius



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IC 4628, also known as the Prawn Nebula or Gum 56, is an emission nebula located in the constellation Scorpius. It is a vast cloud of gas and dust, illuminated by the intense radiation emitted by the hot, young stars (spectral types O and B) within its vicinity. Spanning an impressive 250 light-years across, the Prawn Nebula captivates astronomers and stargazers alike with its intriguing characteristics.

Its intricate tendrils of gas and dust twist and coil, forming a visually striking display in this detailed image. Within this nebula lies a stellar nursery, where new stars are born from the collapse of massive molecular clouds. The stellar nurseries are crucial to keep up with the renewal of stars in every galaxy.

The Prawn Nebula is rich in ionized hydrogen, resulting in the characteristic reddish glow emitted by the region. This glow is caused by the interaction between the intense ultraviolet radiation from the massive stars and the surrounding gas, causing the hydrogen atoms to become ionized and emit light.

Observations of IC 4628 have provided valuable insights into the dynamics and lifecycle of massive stars. The nebula contains several young and massive stars, some of which have already exploded as supernovae. These stellar explosions have shaped the surrounding gas and dust, creating shockwaves that propagate through the nebula, sculpting its structure.

This image has been taken with narrowband filters (Ha, [OIII] and [SII]), as well as short RGB exposures to grab the stars in a more natural color. The filters have been mapped in such a way as to provide the nebula’s natural colors with Halpha mapped to Red and [OIII] to greenish-blue, but with a twist: [SII] has not been mapped to its correct red, but in order to better show the location of the different gases that compose the nebula, has been mapped to bluish-green. This way, all yellowish areas are rich in [SII], as well as the small greenish blue nebula on the upper left quarter. This is a second visit to this nebula and it is another result of the ongoing joint project with Christian Sasse. The first image, taken in 2018, can be found here.


Additional Information


Name(s): IC 4628. Prawn Nebula

Type: Emission Nebula

RA:  16h 56m 54s

Dec: -40º 30’ 53”

Constellation: Scorpius

Size (arcmin): 90×60 arc minutes

Magnitude: +11.0

Distance: 6,000 ly


Date: 2023-05-03 to 2023-05-25

Location: Obstech, Río Hurtado, Chile

Size (arcmin): 27×28 arcmin

Telescope: 24” f/6.5 Reflector

Camera: QHY 461 (11760x8896pix)

Guiding: off-axis guider

Total exposure: 39h 40m (Ha: 14h 40m; OIII: 12h; SII: 10h; RGB: 3h)

Processing: CCDStack, PixInsight (one process) and Photoshop CC 2023



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