OK glen, I'll play this game!
Here are ten favourites of the v. mad galaxy man.
Actually, I will do five galaxies today and five galaxies tomorrow.
NGC 5266
Elliptical/S0 galaxy with a dust lane along the minor axis. Central portions are like an elliptical, but outer portions are disky like an S0.
One of the best examples of a nearby galaxy that is probably the product of a merger between two large galaxies, perhaps the merger of two large spirals. Odd that so many of these "merger products" are not quite any particular Hubble type.....
The inner part that is seen in this image could be taken for an elliptical, but there is also a very unusual low-surface-brightness very-very extended envelope which has characteristics of a disk.
An alternative to the "merger" hypothesis for the origin of the giant LSB outer disk (which is not shown in this image) is that intergalactic gas has gradually fallen into the potential well of this galaxy and thereby Very Slowly formed the faint very-large-scale disk.
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NGC 3256
This small, but high surface brightness, system is a galaxy merger which shows evidence for multiple nuclei. Not sure of the latest science on this one, but the two galaxies have just merged, and the whole system looks very messy as a result.
(prominent tidal tails are not shown in this short exposure)
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NGC 6771
This galaxy illustrates a morphology which is rare amongst the nearby field and Galaxy Group galaxies and which is also rare in the (relatively low galaxy density
) Virgo Cluster. For this reason, it is
not familiar to us, because it is not in the canonical galaxy atlases such as the Carnegie Atlas of Galaxies.
The bulge is what is commonly known as a "giant boxy/X/peanut shaped bulge".
But There are plenty of these galaxies in dense clusters of galaxies!
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NGC 4424
This galaxy is probably the product of a galaxy merger, and it is in the Virgo Cluster. This galaxy cannot be classified by placing it in a single position on the orthodox Hubble Sequence of Hubble types (E - S0- S0/a - Sa - Sb - Sc - Scd -Sd - Sdm - Sm - Irr. )
It illustrates a
novel morphological type or class.
The inner part could be taken for an irregular galaxy or a magellanic spiral, but the outer envelope is smooth, almost like the disk of an S0 galaxy.
Hmmmm......food for thought here!!
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NGC 4435
This one illustrates a lot of important themes in the study of galaxy morphology, for instance:
- There is a bright disk, and there is no evident recent star formation, so this makes the nominal Hubble class to be S0
- However, there is a reasonably bright spheroidal bulge/halo component which is actually
bigger than the disk
- bulges are not supposed to be bigger than disks, but here it is!
- there is also a very small dusty disk (or annulus) hiding in the very centre, which may perhaps show evidence of some residual recent star formation.
(isophotes of NGC 4435)
(is this an elliptical galaxy or an S0 galaxy???......it is hard to say, really. Conceptually, it could be thought of as an elliptical galaxy which contains a disk of modest size, or it could be thought of as an S0 galaxy with an extraordinarily extended bulge)
[ An interesting comparison with NGC 4435 is NGC 3115. In longer exposures, its bulge component looks to extend out from the centre about as far as the planar disk component. ]
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