NGC1399 - Globular Clusters "swarm" image

[madbadgalaxyman (Robert)]

Here is a good image of the Globular Star Cluster "swarm" that belongs to NGC 1399, the giant elliptical galaxy that is near the centre of the Fornax Cluster of Galaxies, which is probably the most prominent aggregation of densely-arrayed Bright Galaxies in the Southern Sky.

The Fornax Cluster of Galaxies, at a well constrained distance of 20 Megaparsecs (= 65 million light years), is the second nearest cluster of galaxies after the Virgo Cluster of Galaxies, though it is totally different in appearance from Virgo, as it is much more symmetrical and it is nearly 100 percent dominated by S0 and Elliptical galaxies which have very little or no residual star formation.

The system of globular clusters is:
- Extremely Rich - some estimates say a total of about 6000 globulars
- Very Extended. For instance Kim et al (in 2013, ApJ, 763, 40) find that the swarm of globular clusters extends to at least 16 arcminutes from NGC 1399.

[it should be mentioned here that the falloff in density of the globular clusters (e.g. number per square arcminute) with increasing distance from the centre of N1399 is very rapid, following an r-to-the-1/4 "de Vaucouleurs" law)
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This image was taken with the CTIO 4m telescope and the MOSAIC camera. It is associated with a paper by Boris Dirsch and colleagues.

Incidentally, for those of you interested in observing or photographing this swarm of globular star clusters, the brightest clusters belonging to NGC 1399 (but only a handful of clusters can be seen at this magnitude) are apparent visual magnitude 20, and the population of globulars only starts to look rich if you can image down to at least V magnitude 23 .
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The system of globular clusters belonging to the nearby Fornax Cluster galaxy NGC 1404 is much poorer and much less extended;
this is, in fact, a normal situation in clusters of galaxies, and the dominant elliptical galaxy always has by far the largest number of globulars.
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Cheers,
Bad Galaxy Man

[madbadgalaxyman (Robert)]

For those of you who want a quick overview and super-summary of ongoing work regarding nearby galaxy clusters like Fornax and Virgo and Coma, here is the 2011 conference on this issue, with downloadable pdf files of the presentations made:

http://www.eso.org/sci/meetings/2011...ram_final.html

Incidentally, the Fornax Cluster of Galaxies remains the poor cousin of the Virgo Cluster, in terms of the number of papers written about it, and this is as true in 2014 as it was in 2004!

To give just one random example, there has been very little published about NGC 1316 in the last 3 years, despite the fact that it is the 'rosetta stone' which can enable us to decipher the history of a galaxy which has undergone multiple mergers with other galaxies;
for instance, Paul Goudfrooij and colleagues, in the 2001 MNRAS, announced the discovery that NGC 1316 contains a large population of globular clusters that are only 3 billion years old, in comparison to the standard 'old' (9-13 billion years old) globular clusters of familiar galaxies like the Milky Way and M31 and M104 and M87.
While there is a fair degree of data that continues to accumulate about this galaxy, this major evolutionary event is still poorly studied and understood.

There is even an unresolved distance controversy about this important galaxy
(17.8 Megaparsecs vs. 20.8 Megaparsecs; the first of these distances puts it somewhat in the foreground of the Fornax Cluster, while the second of these distances puts it in the Fornax Cluster proper)

The Virgo-Fornax comparison is an important one, as Fornax Cluster is in a much more advanced state of evolution, with its smooth structure, and with its galaxies nearly universally being poor in gas and star formation.