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Fast Facts about M104's globular star clusters
Here are some "Fast Facts" about the globulars of M104, taken from this preprint of a paper:
arxiv: 0909.4805 (which was published in the MNRAS around about year 2009).
(the authors are: Harris, Spitler, Forbes, and Bailin)
(Lee Spitler and Duncan Forbes are at Swinburne University)
(Australia's Duncan Forbes is one of the world authorities on Globular clusters. William Harris is virtually "Mr Globular"; he has worked on them all his long life.)
Q. How many globular clusters in total?
A. One estimate is 1,900
(As of 2009, M104 was the spiral galaxy with the largest known population of globular clusters.)
Q. How far away is M104?
A. A modern "compromise" distance is 9.0 megaparsecs (= 29.3 million light years).
Q. Do the globulars of M104 resemble the standard "old"(>= 8 billion years old) globular clusters of the Milky Way, M31, and other nearby galaxies?
A. Yes! Colours, sizes, & luminosities, are all very similar.
(I am not aware of any spectroscopy of the globulars of M104, so we could still get some surprises when it comes to age estimates, but then I am 3 years behind with my reading!)
Q. Are M104 and its globulars significantly affected by the dimming and reddening of its light by the dust within our own Galaxy?
A. No. The foreground Visual extinction is probably only about 0.15 magnitudes.
Q. How big are the globulars of M104, in angular terms, and in real physical dimensions?
A. The radius enclosing half of the total light is in the range 1-5 parsecs, for these clusters, which means that they are essentially stellar sources when seen with ground-based telescopes. But.....Hubble Space Telescope can partly resolve the globulars of M104. The absolute maximum angular dimension of one of these globulars is 0.1 arcsec for the faintest ones and about 0.5 arcsec for the very brightest ones.
Q. Can you see any of these clusters visually in a 20 inch telescope?
A. I believe that the answer to this question is a decisive "no!!"; in fact, I have already addressed this question in another forum, but I need to look it up.
Best regards,
from mad galaxy man
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