NGC 6302. The Bug Nebula


Click on the image for a larger version

NGC 6302 is known as the Bug Nebula or the Butterfly Nebula. Both names show, that we usually choose names based on our familiar images. NGC 6302 is a planetary nebula located in the constellation Scorpius. Its central star is one of the hottest white dwarfs ever identified in the center of a planetary nebula: over 250,000 ºC. This hints to a very massive parent star (probably above 3 solar masses and as high as 5-6 solar masses), before shedding a significant part of its mass as a planetary. Currently, it is believed to have a remaining mass of about 0.64 solar masses and a luminosity of 4,000 times brighter than our Sun. As a normal white dwarf, it is not anymore producing its own energy and is cooling down, fading about 1% per year.


A cropped version, 6.7×4.9 arcmin, of the above image

The nebula’s catalogued size is 1.4×0.4 arcmin, but this only refers to its brighter parts. The current images (and this one is no exception) show fainter regions of the nebula up to 4.8×1.4 arcmin. This nebula has a central disk (torus, not apparent at visible wavelengths) of dust that obscures the central star from sight. This star has only recently (2009) been captured photographically with the Hubble Telescope at a wavelength of 673 nm. The central torus is located nearly edge-on related to our line of sight and its composition is quite complex, with crystalline silicates, carbonates, water ice and quartz.

This image has been taken in narrowband (Ha and OIII) and has been mapped to natural color.


Additional Information


Name(s): NGC 6302. Bug Nebula. Butterfly Nebula

Type: Planetary Nebula

RA:  17h 13m 43s

Dec: -37º 05’ 59”

Constellation: Scorpius

Size (arcmin): 4.8×1.4

Magnitude: +9.8

Distance: 3,500 ly


Date: 2018-04-23 to 27

Location:, SSO near Coonabarabran, NSW Australia

Size (arcmin): 28×19

Telescope: Planewave CDK 20” f/6.8

Camera: SBIG STX16803 (4096x4096pix)

Guiding: Astrodon MonsterMOAG off-axis guider

Total exposure: 4h 40m (Ha: 131 min; OIII: 136 min; RGB: 13.5 min)

Processing: CCDStack, Photoshop CC 2018

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