Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

February 9, 1996

The Eye of an Hourglass Nebula
Credit: R. Sahai and J. Trauger (JPL), WFPC2 Science Team, NASA

Explanation: What's happening in the eye-like centre of this planetary nebula? The geometry revealed in this Hubble Space Telescope view of the central part of an "etched hourglass nebula" known as MyCn 18 presents a puzzle. First, the axis of this central region does not line up well with the outer hourglass structure. Next, the hot star (the white spot to the left of centre) which ejected this gaseous nebula as it evolved towards its white dwarf phase, is not exactly at the centre of the "eye". These unexpected results leave astronomers looking for the missing pieces of the ejection process that created this unusual and beautiful structure.

Tomorrow's picture: The First Explorer

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
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&: Michigan Tech. U.