Right Ascension	18 : 36.3 (h:m)
Declination	-23 : 55.5 (deg:m)
Distance	10.1 (kly)
Visual Brightness	15. (mag)
Apparent Dimension	3 (arc seconds)

Planetary nebula IRAS 18333-2357 or GJJC1 in M22 was discovered by the infrared satellite IRAS (F.C. Gillett, 1989). This faint object is of about 15th visual magnitude and only 3 arc seconds diameter. Lying 1' south of the center of M22, the nebula is an extreme observer's challenge: It is Rich Jakiel's Ultimate Challenge No. 7. Doug Snyder has an excellent IRAS 18333-2357 information page and a detailed IRAS 18333-2357 observer's page with locating info and images; we adopted the image on the right from there.

Below we present images of the faint planetary nebula IRAS 18333-2357:

This is a small region in the globular cluster M22, a dense star cluster about 3 kpc away. Near the center is a very unusual planetary nebula discovered by its distinctive infra-red emission with the IRAS satellite. The nebula is almost undetectable in this image.

This is the exact same picture as the M22 picture above, but a continuum image was subtracted from the {OIII} image above to enhance the visibility of the emission-line nebula. The "dual headlight" white spots just above the center of the picture show the brightest parts of the nebula, but there are also faint wisps tailing away and downward. This nebula is extremely bizarre in that (1) it is only 1 of 2 known in globular clusters, (2) it is only 1 of 4 known to be completely devoid of hydrogen, and (3) it is only 1 of about 3 known to be sweeping through the interstellar medium. The central star is the bright star in the middle of the picture.

Credit: George Jacoby, KPNO

References:

• Gillett, F.C., 1989. Astrophys. J. 338, 862

Planetary Nebulae in Globular Clusters

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Hartmut Frommert (spider@seds.org)
Christine Kronberg (smil@lrz.uni-muenchen.de)

Last Modification: 12 May 1999, 11:00 MET