NGC 6302, Bug Nebula

History

The nebula was discovered in 1880 by Edward Barnard with his private 5 inch refractor at Nashville. He suggested the name «Bug Nebula». [196] Modern high-resolution images show that the nebula more looks like a butterfly why it is also sometimes called «Butterfly Nebula», a name that also used for the planetary nebulae NGC 2346 or Minkowski 2-9.

NGC 6302
NGC 6302: Image taken with Hubble Space Telescope [521]

Physical Properties

The planetary nebula NGC 6302 lies roughly 3800 light-years away. The age of the nebula is estimated over about 2200 years. It stretches for more than 2 light-years.

The central star is hidden within a doughnut-shaped ring of dust, which appears as a dark band pinching the nebula in the center. The thick dust belt constricts the star’s outflow, creating the classic bipolar or hourglass shape displayed by some planetary nebulae.

The star’s surface temperature is estimated to be about 222'000 Kelvin. Spectroscopic observations showed that the gas is roughly 20'000 Kelvin, which is unusually hot compared to a typical planetary nebulae.

The nebula's outer edges are largely due to light emitted by nitrogen. The inner regions are areas where light is emitted by sulfur. These are regions where fast-moving gas overtakes and collides with slow-moving gas that left the star at an earlier time, producing shock waves in the gas. [522]

«Revised New General Catalogue and Index Catalogue» Dr. Wolfgang Steinicke, 2021 [277]
DesignationNGC 6302
TypePN
Right Ascension17h 13m 44.1s
Declination-37° 06' 12"
Diameter1.48 arcmin
Photographic (blue) magnitude12.8 mag
Visual magnitude9.6 mag
Dreyer DescriptionpB, E pf (Swift: triple)
IdentificationPK 349+1.1, ESO 392-PN5, Sh2-6, Bug nebula

Finder Chart

The planetary nebula NGC 6302 is located near scorpio's sting in the constellation Scorpius. The best time to observe it is from May to July, when the part of the constellation is highest above the southern horizon at night. An observation site with a clear view to the south is required here, because the nebula, with a declination of -37° in Switzerland, comes barely 10° above the horizon when it is in the meridian.

Chart NGC 6302
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
521NGC 6302; esahubble.org/images/heic2011b (2022-06-09)
522NGC 6302; nasa.gov/mission_pages/hubble/multimedia/ero/ero_ngc6302.html (2022-06-09)