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This region is interesting because it is an active stellar nursery. In a paper published in 2009, Keely Snider et al., analyzing data from the Spitzer Space Telescope, identified 45 candidate YSOs (Young Stellar Objects). The interesting fact is that these YSOs were not randomly distributed, but rather concentrated (75% of them) at the edge of the HII region, along the ionization fronts, that are driven by the radiation emitted by the nearby massive stars. Five of the YSOs have been labelled in the annotated copy below. According to Snider, #5 is the youngest one, a mere 2,000 years old and #16 is the oldest one, about 1,200,000 years old.
The bright star at the center of the “bowl” is HD 64315, an O6 star (mag 9.5) belonging to the NGC 2467 open cluster, that is responsible for the ionization of this region. The open clusters Haffner 18 and 19 are gravitationally linked as a double cluster and Wray 15-101 is a B-type star ionizing its immediate region.
This image has been taken with narrowband filters (Halpha and OIII). Halpha images were taken through a 3nm bandpass filter that left “untouched” the Easternmost (left) of the nebula, allowing the faint but remarkably clear greenish-blue OIII emission to pop up. This fact allows for the beautiful loops, only visible with this filter, to show off. In LRGB images, the broadband red dominates and wipes out most of this faint color. The nebulosities surrounding Haffner 19 as well as Wray 15-101 are really pure Hydrogen-red, as they go undetected in the OIII images.
Name(s): NGC 2467. The Skull and Bones Nebula
Type: Emission Nebula
RA: 07h 52m 33s
Dec: -26º 26’ 48”
Size (arcmin): 14×14
Distance: 13,200 ly
Date: 2018-01-28 thru 2018-03-10
Location: iTelescope.net, SSO near Coonabarabran, NSW Australia
Size (arcmin): 37×37
Telescope: Planewave CDK 20” f/6.8
Camera: SBIG STX16803 (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 11.5 hours (Ha: 7.5h; OIII: 2.5h; RGB 1.5h)
Processing: CCDStack, Photoshop CC 2018