NGC 6357 (RCW 131, Gum 66, Sh 2-11, War and Peace Nebula, Lobster Nebula) Diffuse Nebula and Open

Cluster Pismis 24 in Scorpius

(move the mouse over thumbnails - please be patient until image downloads)

 
16" DCA: LRGB 16" DCA: L-HaRGB 16" DCA: Ha 12" ASA: LRGB 12" ASA: HaLRGB  
Size: 2000 px Size: 2000 px Size: 2000 px Size: 2000 px Size: 2000 px  
 
Downloading, please wait ...
© Velimir Popov & Emil Ivanov 2013
 

John Herschel discovered this nebula on June 8, 1837 from the Cape of Good Hope, and cataloged it as h3682 in his 1847 catalog. It became GC 4297 in his General Catalogue of 1864, and NGC 6357 in J.L.E. Dreyer's NGC.

NGC 6357, is a diffuse nebula in the constellation Scorpius. The nebula is ionised by the star cluster Pismis 24 which includes the massive multiple O4 and O4-5 star system as well as the Wolf-Rayet star WR 93, which is also a multiple star system with a class O7-9 companion. The overall red glow near the inner star forming region results from the emission of ionized hydrogen gas. The intricate patterns are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity. NGC 6357 spans about 400 light years and lies about 8 000 light years away. The star-forming nebula NGC 6357 show no evidence of a blue component in its colour. The frame taken with blue filter had no nebulous image at all, only a few traces. Such an object is excellent example of the phenomenon known as 'interstellar reddening', the selective removal of blue light by trifling particles of dust. This accounts for both the ruddy hue and apparent absence of blue stars. The hot stars are present but only some of the red part of their light is seen so they are not conspicuous.

Pismis 24 - This nebula includes the open cluster Pismis 24, which is home to several massive stars. One of the brightest stars in the cluster, Pismis 24-1, was thought possibly to be the most massive on record, approaching 300 solar masses, until it was discovered to be at least the triple system with each star exceeding 70 solar masses.

Object details

Right Ascension 17:24:43.5 (h:m:s)
Declination -34:12:05 (deg:m:s)
Distance ~ 8 000 (ly)
Apparent Dimension 50 (arc min)

Image details

Annotation

ASA 12"

Center of field RA 17:24:28 (h:m:s)
Center of field DE -34:14:08 (deg:m:s)
Size 57.4 x 43.2 (arcmin)
Pixel scale: 1.03 (arcsec/pixel)
Orientation: Up is -2.04 degrees E of N

DCA 16"

Center of field RA 17:25:00 (h:m:s)
Center of field DE -34:18:37 (deg:m:s)
Size 1.37 x 1.37 (deg)
Pixel scale: 1.23 (arcsec/pixel)
Orientation: Up is -178 degrees E of N
Charts and image details obtained from Astrometry.net
ASA 12"
Optic(s): ASA 12" f 3,6 Astrograph (ASA)
Mount: ASA DDM85
Camera: FLI MicroLine 8300 CCD camera
Filters: Lum, Red, Green, Blue, Ha, OIII and SII Astrodon
Dates/Times: From 3 to17 of May 2013
Location: Namibia-TIVOLI ASTROFARM, S 23° 27' 40,9" / E 18° 01' 02,2"
Exp. Details: Ha: 8x15min, L: 3x10min, R: 4x10min, G: 3x10min, B: 3x10min, Bin 1
  Total Exposure Time - 250 min (4:10 hours)
More details: Dark and flat frames reduction
Processing: PixInsight / PS
DCA 16"
Optic(s): 16" f3,75 Dream Corrected Astrograph (DCA)
Mount: Astelco NTM-500 direct drive mount
Camera: Apogee Alta U-16M CCD camera
Filters: Lum, Red, Green, Blue, Ha, OIII and SII Astrodon
Dates/Times: From 3 to17 of May 2013
Location: Namibia-TIVOLI ASTROFARM, S 23° 27' 40,9" / E 18° 01' 02,2"
Exp. Details: Ha: 7x15min, L: 6x10min, R: 6x10min, G: 6x10min, B: 4x10min, Bin 1
  Total Exposure Time - 325 min (5:25 hours)
More details: Dark and flat frames reduction
Processing: PixInsight / PS
 
Copyright: Velimir Popov and Emil Ivanov 2013. All Rights Reserved
 
e-mail: info@irida-observatory.org
click tracking