Milky Way's Mass

[LeaderOne]

Hi:
I hope some of the astronomers over here can help me find this: I remember reading a paper last year on the internet that discuss the currently estimated mass of the milky way galaxy extrapolated from several methods (at least more than the rotational curve only). In the paper it was concluded that the results were roughly in agreement to consider the mass of our galaxy around 1.5 billion (10^12 kind of billion, not the american one) solar masses, and thus being more massive than M31, contrary to what it was believed. (Andromeda is still larger in diameter because it seems that due to a recent collision-assimilation of a satellite, it was "puffed up" -and it was believed this could account for almost a 50% increase in size). I've been searching for that paper, or for that matter, updates in astronomy websites that recognized that fact, but everywhere it seems that M31 is still considered the more massive. If somebody remember reading something like this and help me find that paper to confirm it's proposition or not, I will appreciate it greatly!
thanks!

[guest]

I never knew that we Americans thought of a billion differently than the rest of the world. What does the rest of the world call 1,000,000,000 (american for billion) and what do americans call 10^12 (1,000,000,000,000)? This is a trillion, right? Does the rest of the world have a trillion too?

[granthutchison]

What does the rest of the world call 1,000,000,000 (american for billion)

A thousand million.

Does the rest of the world have a trillion too?

Yes, 10^18.
But I'm not sure to what extent it's "the rest of the world" - it might just be a waning British tradition (which is, of course, the older and therefore more correct version ... )

The original meanings of "billion", "trillion", "quadrillion" etc , dating back to the sixteenth century, were successive powers of one million - a million squared, a million cubed, a million to the power four, and so on. For some reason in the middle of the seventeenth century there was a switch to the system that's now current in the US, where each successive power of a thousand gets its own name. I don't know what system the rest of Europe are currently using .

Grant

Edit: Originally I wrote that the French had led the switch to the system now used in the US (see the quoted text in Jamarsa's post below), but I'd misread my reference - French authors described the change, but I've no evidence it was ever used in France ...

[granthutchison]

LeaderOne:
Is this the paper you're looking for?

Grant

[jamarsa]

The original meanings of "billion", "trillion", "quadrillion" etc , dating back to the sixteenth century, were successive powers of one million - a million squared, a million cubed, a million to the power four, and so on. For some reason in the middle of the seventeenth century the French switched to the system that's current in the US, where each successive power of a thousand gets its own name. I don't know which system the French, or indeed the rest of Europe, are currently using .

As far as I know, the original one (powers of a million), and they use the word 'milliard' instead of the english 'billion'. At least it is here in Spain. I'm always amused when a spanish reporter incorrectly translates an american quote, making the quantities much bigger than they really are... Things like the age of the Earth, for example. If you believe some TV news reporter, it's older than the age of the universe.

Look at the Wikipedia for more info.

[LeaderOne]

Thanks Grant! I knew you guys are always good sources!
I still wonder, even with the large error margin, why this study haven't reach the mainstream astronomy reference sources. And considering that this study considers all available methodology and data with our current knowledge, compared with the traditional asumption based on more limited data and extrapolations, I really wonder...

Not totally out of silly pride, but I would like to hear more often that we live in the largest home of the neighborhood...

About the billion, well, the only country of the many I visited that use the form 1,000,000,000 = 1 billion is the United States. The other form appears to me more logical. Well, then we have football, not soccer, and feet, not meters

[granthutchison]

Look at the Wikipedia for more info.

Thanks for the link jamarsa. I confess I wondered if the old usage was now just a British hold-out - nice to know it's standard in the rest of Europe. The word milliard for a thousand million has been used in Britain (I remember first encountering it in a novel by HG Wells), but it doesn't seem to have caught on here.

Grant

[Guest]

In fact, I've just remembered the poem by Piet Hein:

Life, it would seem, is simply our name
For milliards and milliards and milliards
Of particles, playing their infinite game
Of billiards, and billiards, and billiards.

Sorry, I've drifted completely off-topic. I'll shut up now.

Grant

[Guest]

In fact, I've just remembered the poem by Piet Hein:

Nature, it seems, is the popular name
For milliards and milliards and milliards
Of particles playing their infinite game
Of billiards, and billiards, and billiards.

Sorry, I've drifted completely off-topic. I'll shut up now.

Grant