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Q: Number of Galaxies and Stars in Each ( No Answer,   2 Comments )
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 Subject: Number of Galaxies and Stars in Each Category: Science > Astronomy Asked by: geoffreysteven-ga List Price: \$20.00 Posted: 11 Nov 2005 09:18 PST Expires: 11 Dec 2005 09:18 PST Question ID: 591923
 ```How many stars are in our Galaxy and how many Galaxies are estimated to exist. For the former I have heard 200 Billion and the latter, 100 Billion. I am trying to figure out, roughly speaking, how many stars exist.``` Clarification of Question by geoffreysteven-ga on 11 Nov 2005 14:46 PST ```Specifically, what percentage of the total stars would be : brown dwarfs, neutron stars, stars like ours or large giants. And of those, what percentaage would like be binary or triple systems?```
 ```They don't provide a breakdown, but according to Monty Python: Our galaxy itself contains a hundred billion stars. It's a hundred thousand light years side to side. It bulges in the middle, sixteen thousand light years thick, But out by us, it's just three thousand light years wide. We're thirty thousand light years from galactic central point. We go 'round every two hundred million years, And our galaxy is only one of millions of billions In this amazing and expanding universe. http://arago4.tn.utwente.nl/stonedead/movies/meaning-of-life/ra/galaxy-song.ra```
 ```Best current estimate of stars in the Milky Way is 110 Billion with an error rate of +/- 20%. Most current published estimate of galaxies in the Universe is 125 Billion, as reported in 1999 by the Hubble program. This probably has a much larger probability of error, probably +/- 50% or more. As to your other question about types of stars, this is a little more dicey. The distribution of star types is constantly being skewed as some star types morph into others, and forther complicated by the fact that each star class has a different expected life span. The typical middle-of-the-road star, so to speak, would be about 2-4 time our sun's mass. Our sun, despite the mythology that it is an "average star", is actually a rater diminutive star. Eventually, all stars in our galaxy will become either a brown/black dwarf, a neutron star, or a black hole. Because all of these objects are very difficult to account for, especially at great distances, it is unknown how many of these objects already exist in our galaxy. I believe that visable stars fall into a bell-curve distribution, with the mean being about 3 solar masses and the standard deviation being (a wild-ass guess) about 1-1.5 solar masses, and heavily skewed towards the left, with a long flat tail extending to the right for more than 100 stdev's.. Red Giants are very short-lived stars in this form, as they are very geometricly large for their associated mass. Usually, thet are a smaller sun in the final throws of death and metamorphisis. This being the case, their life span is very short relative to other stars, which can further be argued that since they individually occupy a very thin slice of galactic time, then they are by definition very rare. White Super Giants, like Deneb, which are the big-dawgs of the galaxy, probaly number in the hundereds for the entire Milky Way, or roughly 1 in a billion, while 80%+ of visable stars will fall in the 1-5 solar mass range. Again, a wild-ass guess based on personal data collection and observations. Hope this helps..```