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Astrophysics/How close to confirmed it is that our galaxy is 50% larger?



On this year there where news about our galaxy being fifty percent larger than we had previously estimated it to be. This would put our galaxy at a hundred and fifty thousand to a hundred and eighty light years across.

So my questions are as follows:

1) How close to confirmed is this new find?

2) And if this indeed is confirmed, will it also lead to an increase in the estimate of how many stars our galaxy has?

Have a nice day. :)

I'm going to preface this by saying that this is not in my direct research area of expertise.  You're asking about observational astronomy (telescopes observing stuff) and not astrophysics (processes one may study in the laboratory).  You're also asking a question about something like "is Pluto a planet?" which involves human opinion on where the density of stars drops off enough to say that the Milky Way "ends."  Some person has to determine that boundary based on the available data, which is not something I study nor do I have an opinion on what that number should be.

That said, it may seem surprising that we don't just look around at the closest stars in the universe and come up with a solid number...but we're seeing out galaxy from the inside.  The research suggesting that the disk of the Milky Way has ripples and therefore we should define stars that are "within" the Milky Way to be inside a much larger disk does appear to be solid work.  I don't doubt it.  Stellar distances are very difficult to compute, we learn more about that process all the time.  How do you tell the distance to a point of light that has no apparent size?  It took a very long time for humans to determine the distance to the Sun itself.  That's why such an important number to know accurately created such a massive race to measure the transit time of Venus across the Sun, a rare astronomical event that we will not see again soon since the last one was only a few years ago.  

The extension of the human-defined "boundaries" of our galaxy does change our picture of the outer part of the galaxy itself, but does surprisingly little to alter our understanding of things like our own orbit within it or the mass of the central bulge.  I'm sure it will impact some dark matter research, as we observe the motions of stars we wouldn't have previously considered to be "within" our galactic plane (since the plane has ripples, according to the new work).  These impacts will not be life-altering or paradigm-shifting.  It will, to answer your second question, increase (not dramatically) the estimate of the number of stars "in" the Milky Way.


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Dr. Stephen O. Nelson


Fusion, solar flares, cosmic rays, radiation in space, and stellar physics questions. Generally, nuclear-related astrophysics, but I can usually point you in the right direction if it's not nuclear-related or if it's nuclear but not astrophysics.


Just moved from being a physics professor at the University of Texas of the Permian Basin into government work. Doctoral dissertation was on a reaction in CNO-cycle fusion, worked in gamma-ray astronomy in the space science division of the naval research laboratory in the high-energy space environment branch.

Government work as a physical scientist with a nuclear focus.

Ph.D. in physics, research was on nuclear fusion reactions important in stellar fusion, further work on space telescope technology.

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