| Emission nebula | |
|---|---|
| Planetary nebula | |
 1996Hubble Space Telescope image of the Hourglass Nebula | |
| Observation data:J2000epoch | |
| Right ascension | 13h 39m 35.116s[1] |
| Declination | −67° 22′ 51.45″[1] |
| Distance | 8,000 ly |
| Apparent magnitude (V) | 13.0[1] |
| Constellation | Musca |
| Physical characteristics | |
| Radius | 0.29 ly |
| Absolute magnitude (V) | - |
| Notable features | It looks like an eye |
| Designations | ESO 97-1,[1] Engraved Hourglass Nebula,[1] |
| See also:Lists of nebulae | |
TheEngraved Hourglass Nebula (also known asMyCn 18[2]) is a youngplanetary nebula in the southern constellationMusca. It was discovered byAnnie Jump Cannon andMargaret W. Mayall during their work on an extendedHenry Draper Catalogue (the catalogue was built between 1918 and 1924). At the time, it was designated simply as a small faint planetary nebula. Much improved telescopes and imaging techniques allowed the hourglass shape of the nebula to be discovered by Romano Coradi and Hugo Schwarz in images taken during 1991–1992 at theEuropean Southern Observatory.[3] It is conjectured that MyCn 18'shourglass shape is produced by the expansion of a faststellar wind within a slowly expandingcloud which is denser near its equator than its poles. The vivid colours given off by the nebula are the result of different 'shells' of elements being expelled from the dying star, in this casehelium,nitrogen,oxygen andcarbon. The central star of the nebula is unknown.
The Hourglass Nebula was photographed by theWide Field and Planetary Camera 2 of theHubble Space Telescope.
A less-famous "Hourglass Nebula" is located inside theLagoon Nebula.
