Bug Nebula (NGC 6302)

NGC 6302
NGC 6302: Image taken with Hubble Space Telescope. © ESA/Hubble & NASA [521]

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]

While searching the photo plates of the «Palomar Observatory Sky Survey» for H-II regions, the American astronomer Stewart Sharpless came across the this nebula and listed it as Sh 1-3 and Sh 2-6 in his catalogues published in 1953 and 1959. [309, 310] Colin S. Gum listed the nebula in 1955 as Gum 60 and noted that it is «a doubtful planetary» by Vorontsov-Velyaminov in 1934 «but the form of the objects suggests a diffuse nebula.» [555]

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.

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]

«Strasbourg-ESO Catalogue of Galactic Planetary Nebulae» Acker et al., 1992 [141]
DesignationsPN G349.5+01.0: NGC 6302, PK 349+01.1, ARO 502, ESO 392-05, Gum 60, He 2- 204, RCW 124, Sa 2- 180, Sh 1- 3, Sh 2- 6, VV 94, VV' 168, Wray 16- 259
Right Ascension (J2000.0)17h 13m 44s
Declination (J2000.0)-37° 06' 06"
Dimensions 44.5" (optical), 10." (radio)
Radial Velocity-39.0 km/s ± 2.1 km/s
Expansion Velocity 8.0 km/s (O-III)
C-Star DesignationsAG82 233, CD -36 11341, CPC 18 8579, GCRV 9926, HD 155520
C-Star Magnitude>21.1 mag (B filter)
DiscovererFLEMING 1896

Finder Chart

The planetary nebula NGC 6302 is located near scorpio's sting in the constellation Scorpius. The best time to observe it is in the short summer nights 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 Bug Nebula (NGC 6302)
Bug Nebula (NGC 6302) in constellation Scorpius. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±15°)

References

141Strasbourg-ESO Catalogue of Galactic Planetary Nebulae; A. Acker, F. Ochsenbein, B. Stenholm, R. Tylenda, J. Marcout, C. Schohn; European Southern Observatory; ISBN 3-923524-41-2 (1992); cdsarc.unistra.fr/viz-bin/cat/V/84 (2021-02-18)
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)
309«A Catalogue of Emission Nebulae Near the Galactic Plane» Sharpless, Stewart; Astrophysical Journal, vol. 118, p.362, November 1953; DOI:10.1086/145765; Bibcode:1953ApJ...118..362S
310«A Catalogue of H II Regions» Stewart Sharpless, US Naval Observatory, 1959; DOI:10.1086/190049; Bibcode:1959ApJS....4..257S
521NGC 6302; esahubble.org/images/heic2011b (2022-06-09)
522NGC 6302; nasa.gov/mission_pages/hubble/multimedia/ero/ero_ngc6302.html (2022-06-09)
555«A Survey of Southern HII Regions» Gum, Colin S.; Memoirs of the Royal Astronomical Society, Vol. 67, p.155, 1955; Bibcode:1955MmRAS..67..155G