Milky Way Mass: 60,000 Ly from Galactic Center

[ViperSRT3g]

I just read this article on phys.org, and am now looking for any further insight into this. The article claims that the milky way may have approximately 210 billion solar masses of matter within 60,000 ly of the galactic center. If this is true, wouldn't that make the milky way nearly twice the size of Andromeda?

 

[ArmanCham]

"According to a study published in 2014, the mass of the entire Milky Way is estimated to be 8.5×1011M☉,which is about half the mass of the Andromeda Galaxy." Quote from Wikipedia we know that Milk way mass is half of Andromeda that's sure.
Here what I found about size of andromeda http://space-facts.com/andromeda/ its 250.000 ly but milk way 100.000

 

[ViperSRT3g]

Yes, I Googled the mass of the Andromeda galaxy and found the wikipedia page on andromeda with the stated mass which is how I based the approximate twice the size statement. I'm looking for further insight into other studies that focus on the mass of our own galaxy as it is the one that is under scrutiny here.

 

[Shobah]

The paper you're referencing (which the article was based on) actually contains a great summary of the methods that people have used in the past to weight the Milky Way, which references to relevant sources. You can find the full paper (Kupper+ 15) here:

http://arxiv.org/abs/1502.02658

The entire Section 4 of the paper is devoted to comparing the values they got for the Milky Way mass and other Milky Way parameters with values that other studies have obtained and explaining the different approaches. I recommend you go read it, it's quite clear. It starts like this:

Weighing the Milky Way and its components has been one of the major goals in Galactic dynamics within the last few decades. Since the total mass of the Galaxy is vastly dominated by the extended dark halo, weighing the entire Galaxy basically boils down to determining the mass profile or gravitational potential of this halo. Various attempts have been made at constraining its virial mass, or the halo mass enclosed within a certain limiting radius, using all kinds of available tracers of the Galactic matter distribution. Some approaches also attempted to constrain the shape of the dark matter distribution, i.e. its flattening or triaxiality. Here we list a few of the more recent measurements, first for the enclosed mass and then for the shape of the dark halo.

My impression from skimming through Section 4 it is the mass is only known within a factor of 2-4, due to the variety of proxies that can be used. It wouldn't surprise me if the mass of Andromeda was known better, since we see the effect of mass on satellite galaxies more easily.

Hope this helps!