SUNSET: 
0
Photographer:
Hal Heaton
Location of Photo:
Chilescope, Telescope 4
Date/Time of photo:
April 25, 28, May 25, 26, 2021; Full Moon
Equipment:
Camera: Unguided FLI Microline 16200 fitted with a Nikkor 200:2 lens (100 mm aperture, f/2); Filters: Astrodon H-alpha and OIII; Exposures: 180-sec, stacked for 2-hrs in each band; Plate Scale: Unbinned, 6.3 arcsec/px.
Description:
The Vela-Puppis region of the southern sky features the largest ionized hydrogen nebula in the Galaxy (Gum 12). Centered on the massive spectroscopic-binary star Gamma2 Velorum, comprising an O7.5 giant and a Wolf-Rayet companion, and the surrounding Vela OB2 stellar Association, it is thought to be the remnant of an old supernova explosion that occurred roughly a million years ago. The smaller and much younger Vela Supernova Remnant featured in this image is immersed in this region at a distance of about 900 light years away. Laced with intertwining filaments and loops of excited oxygen (blue) and both filamentary and more diffuse hydrogen (red), the Vela SNR originated with the explosion of another massive star sometime between 11,000 and 12,300 years ago. The eventual recognition of the affiliation of this smaller remnant and the Vela Pulsar (PSR J0835-4510), located just below the closed blue ring at the upper center of the image, provided direct observational evidence that supernova explosions produce rapidly-rotating neutron stars. The continued ionization of these filaments so long after that explosion probably results from prodigious ultraviolet radiation emitted by Gamma2 Vel and perhaps other OB stars in its proximity, which lie just beyond the upper left corner of the frame. The remotely-acquired data for this 7.7 x 6.0 deg image, which is centered on the more distant Pismis 4 star cluster, were processed into an initial HOO color image in CCDStack, from which grayscale superluminance and mean red, green and blue frames were derived. After blending these with the original narrowband means in Photoshop CC 2019 to emphasize detail, they were high-pass filtered, noise-reduced and reoriented to place north down and east to the right.
