NGC 2392


In Gemini

From Jim Kaler's STARS; Return to Planetary Nebulae

NGC 2392 NGC 2392
Among the most wonderfully intricate of planetary nebulae, NGC 2392 in Gemini, famously nicknamed "the Eskimo" because of the outer "parka" that seems to surround a face, is also among the brightest. The obvious, near-tenth magnitude (10.5) central star quite stands out about 2.5 degrees to the east- southeast of Delta Geminorum, and is visible in even a small telescope. Curtis's drawing on the left, a composite of several photos, bears a remarkable visual resemblance to the spectacular Hubble view on the right (the latter slightly tilted to the right from north). NGC 2392 is also the champion of the double-shell nebulae (another fine example of which is NGC 7662), wherein the inner shell seems to have been compressed from the surrounding matter by a hot wind, and the outer shell shows the "comet-like" structures so easily seen in the Helix (NGC 7293). With a little imagination, the inner ring rather jumps out as a three-dimensional sphere.

The distance, not really known, seems to fall between 2000 and 4000 light years. The inner shell is about 16 seconds of arc across, the outer about double that. If at 3000 light years distance, the inner regions is then about a quarter of a light year wide. The inner portion has an unusually high expansion velocity of 53 kilometers per second, more than double the usual value.

At 65,000 Kelvin, the central star is only (for planetary nebulae) modestly hot, while the luminosity is in the thousands of Suns.

Left: Image by H. D. Curtis from Publications of the Lick Observatory, Volume 13, Part III, 1918. Right: NASA, Andrew Fruchter and the ERO Team [Sylvia Baggett (STScI, Richard Hook (ST- ECF), Zoltan Levay (STScI)].