[QUOTE=Weltevreden SA;969896]
The Harris catalog provides much data, but no images or CMDs. I fill in that info using
Marco Castellani's website. He really keeps it up to date: little-visited GCs like te Djorgovskis and Haute Province 1 are there. I'm impressed by how many 'amateurs' and semi-pros go to such enormous effort to collect and update info that very few will use on serious projects. Unsung heros, the whole lot.
Re Dr. Freeman and his plans to do astroseismology on Galactic bulge stars,
this paper just showed up on arXiv to demonstrate where Dr. Freeman's info might shed light (literally) on some problem areas. The 'boxy bulge' has had astronomers devising explanations for quite awhile now. [QUOTE]
You obviously know and understand globular clusters much better than the typical advanced amateur astronomer. Keep on looking at this data, as I am sure you will find something interesting, anomalous, or unusual! A lot of things are discovered simply by prolonged brooding about data.
(e.g. I have had some definite success finding some unusual galaxy morphology, to the degree that it has been thought worthy of further investigation by professional astronomers. Obviously, galaxy morphology and classification is the area where I have detailed knowledge)
Apparent Bulges, as observed in two-dimensional images of disk galaxies, are
not necessarily spheroidal in shape, and even where they
are spheroidal, they can be either oblate spheroids or they can be prolate spheroids (or even triaxial spheroids!).
Some so-called 'bulges', for instance, while
looking like strong central brightenings that are observed in a face-on galaxy, actually turn out to be
planar structures that are essentially a phenomenon of the central part of the planar disk of a galaxy;
this sort of inner structure is called a pseudo-bulge. (e.g. NGC 6946 and M101 do not have real bulges, as the central bright part of the galaxy is simply an extension of the disk, inwards). (It looks to me like the recent image of NGC 2997 in our imaging forum shows a pseudo-bulge or spiralling inner-disk, which is perhaps(?) superposed on a small 'classical' spheroidal bulge)
(as we know from the stellar population concept, several different kinematic, structural, and age, components can be superposed in a single part of a galaxy, so things can get very complex)
Three-dimensional Bulge Shape and the actual bulge size
cannot be determined using old-fashioned qualitative methods such as Hubble classification, but instead require detailed modelling of isophotes, mass distribution, stellar orbits, etc. (many of the bulge prominence estimates made using visual galaxy classification turn out to be entirely wrong, for technical reasons which I won't go into!)
Ken Freeman, Francois Combes, Martin Bureau, and other workers such as Ron Buta and David Block, have found, on kinematic grounds, that a
bar structure, when seen in an
edge-on galaxy, looks like a Boxy or Boxy/X-shaped bulge. When they say there is a 'boxy/X-shaped, or peanut shaped' bulge, there exists a co-existence of an X-shape and a box (or peanut) shape in the observed two-dimensional bulge morphology that is seen in an image of a galaxy.
On the other hand, very large examples of boxy/x-shaped bulges have been explained as resulting from merger or cannibalization of galaxies.
Small boxy bulge examples:
The Milky Way, and also here is a photo of NGC 5746....
Boxy/X-shaped bulge example:
NGC 3628 (optical image, and an NIR image)
Note that the extreme extensions of the arms of the 'X' make the overall structure to seem very extended indeed; a challenge for theorists to understand. Is the 'X' actually a bulge at all?
Large Boxy/X-shaped bulge example :
NGC 6771
This is a common S0 galaxy morphology in some galaxy cluster environments, though it is not very familiar in the local population of bright galaxies. Some people would call this bulge peanut-shaped.
