Fornax Dwarf Spheroidal Galaxy (Gary Imm)

Fornax Dwarf Spheroidal Galaxy

At first glance, this image appears to be a noisy star field. But upon closer inspection, you can see that the "noise" is actually a dwarf galaxy. And upon even closer inspection using the full resolution view, you can clearly see 6 globular star clusters within this galaxy.

The galaxy is the Fornax Dwarf Spheroidal Galaxy, an elliptical dwarf spheroidal galaxy located almost half a million light years away in the southern constellation of Fornax. In absolute magnitude, it is the brightest dwarf galaxy orbiting the Milky Way. This galaxy was discovered in 1938 by Harlow Shapley. Because of its southern declination (-35 deg) and the need for clear, sharp stars, I had to wait for a night of excellent seeing.

The annotated image above identifies the 6 globular clusters - Fornax 1 through 6. Each of these clusters is less than 30 seconds in apparent diameter. Fornax 3, the brightest extra-galactic cluster in our sky at mag. 12.6, has been given a designation - NGC 1049. This globular cluster was discovered by John Herschel in 1835, long before the galaxy itself was discovered.

Scientists have not yet explained how a single globular cluster (much less 6) could form in an old, relatively gas-poor galaxy. One possibility is that this galaxy captured an even smaller dwarf galaxy sometime in the past.

Fornax 6 is an interesting object, appearing distinctly different from the other Fornax globular clusters. As recently as 25 years ago, this object was still believed to be a cluster. Recent work has shown that a number of the "stars" within this object are non-stellar. Fornax 6 is likely a compact group of very distant galaxies, likely at least 2 billion light years in the background.

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Status	Advanced success
Started	...
Astrometry.net job	8937489
PixInsight job	3VI9Q03VYF854DJSTBTOE30YKAR2YIFT
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	02h39m35s.96
RA (top/left)	02h45m31s.50
RA (top/right)	02h33m49s.96
RA (bottom/right)	02h33m33s.10
RA (bottom/left)	02h45m28s.70

Dec (center)	-34°30′49″.9
Dec (top/left)	-33°42′54″.7
Dec (top/right)	-33°39′58″.6
Dec (bottom/right)	-35°17′37″.3
Dec (bottom/left)	-35°20′41″.5

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