[PNe in GCs Home]
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GOOD HUNTING & DARK SKIES!
I have created this page to serve as a jumping on point to four current observation challenges for amateurs with the desire, patience (and equipment) to attempt to log these four planetaries which are located within the gravitational boundaries of Globular Clusters. It is estimated that globular clusters may contain from 10,000 to over 1,000,000 stars concentrated within a volume of from several 10's of light years to over 200 light years in diameter. All the stars that make up a GC are gravitationally bound with each other and it has been found that a large number of GC's are concentrated around the Galactic Center of our galaxy, the Milky Way. Of the 130+ GC's known and the tens of millions of stars which are contained in them, only four GC's have been found to harbor single planetary nebulae (PNe). For much more information on GC's, the SEDS web site is a great resource for all astronomical objects. Be assured that none of these four objects are easy catches, and the latest two are definitely in the 'possibly impossible' category. But give them a try and prove me wrong!
The second PNe discovered was found to be near the 'core' of GC M22 (NGC 6656) in Sagittarius. This PNe was first noticed in the IRAS mission catalog as an infrared point source and its original designation was IRAS 18333-2357 (1985). Further study of this point source by a group of astronomers in 1988 which included F.C. Gillett, G.H. Jacoby, R.R. Joyce, and J.G. Cohen led to the determination that this was a newly discovered PNe within a GC. The additional designation attached to this PNe was GJJC1. Their paper on this discovery is Astrophys. J. 338, 862, 1989. This is an extremely difficult object to locate and observe, but as of June, 2001, I have received six positive reports, with telescopes ranging in size from 10" to 36" (in between: 20", 20", 22", 25")
The third & fourth PNe's to be found within GC's came about through a survey of 133 galactic globular clusters conducted exclusively to find PNe's within galactic GC's. This survey, led by astronomers George H. Jacoby and L. Kellar Fulton (among others), led to the announcement of these two discoveries in 1997 (1997AJ....114.2611J). The objects discovered were found to be within the gravitational boundaries of the GC's Palomar 6 in Ophiuchus and NGC 6441 in Scorpius. The newly found PNe's have the designations of JaFu1 (GC Pal6) and JaFu2 (GC NGC6441). Note that both ground based and HST instruments were used to obtain images and data for these objects. There has been no positive observation reports received by me on these two objects (As of June, 2001).
Author: Doug Snyder