4 ms·
I'd like to see this plotted on two dimensions, where the horizontal axis is the year, starting when radio emissions began, and the vertical axis is the number
by pohl 16y ago
I'd like to see this plotted on two dimensions, where the horizontal axis is the year, starting when radio emissions began, and the vertical axis is the number of non-sol star systems that are within the bubble at that time. Binary or trinary systems would count as 1 system, not 2 or 3. This function would obviously be monotonically nondereasing.
I wonder if wolfram alpha could rise to the challenge.
- spullara 16y agoUsing the NStED database of stars I find that there are 11,384 cataloged stars within a 200 light year bubble. I thought that it would probably follow an r^3 function but it appears that it follows something closer to an r^2 function - perhaps that is explained by the flatness of the galaxy or just noise? For example, within 20 light years there are only 77. Stars by Distance: http://dl.dropbox.com/u/3924269/plot_10956.jpg http://dl.dropbox.com/u/3924269/plot_10956.jpg NStED: http://nsted.ipac.caltech.edu/ http://nsted.ipac.caltech.edu/
- pohl 16y agoThank you. 11k is higher than I would have guessed. I don't understand your graph. What is the RA axis?
- gjm11 16y agohttp://en.wikipedia.org/wiki/Right_ascension http://en.wikipedia.org/wiki/Right_ascension
- ars 16y agoYah, the galaxy is very flat. Depending on how you define the thickness (do you go by majority of stars, or include all outliers) proportionally the galaxy is flatter than a sheet of paper.
- AngryParsley 16y agoI don't think that's true. Other galaxies don't appear as thin or as flat as paper. (Examples: http://apod.nasa.gov/apod/ap031008.html http://apod.nasa.gov/apod/ap031008.html http://apod.nasa.gov/apod/ap020703.html http://apod.nasa.gov/apod/ap020703.html http://apod.nasa.gov/apod/ap060612.html http://apod.nasa.gov/apod/ap060612.html) Typically they're about 100x wider than they are thick.
- ars 16y agohttp://www.astronomycafe.net/qadir/q546.html http://www.astronomycafe.net/qadir/q546.html "....the thickness of the Milky Way is 50/100000 or 5/10000 of its maximum size making it flatter than a sheet of writing paper." You can not calculate how flat something is by estimating from such a photo!
- AngryParsley 16y agoWikipedia says the stellar disc of the Milky Way is 1,000 light-years thick and cites http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980317b.html http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980317b.... . The core is thicker. Even the image on the page you linked to shows an object that is much thicker than a piece of paper.
- ars 16y agoDid you miss the part where I said: "Depending on how you define the thickness" ? The milky way does not have a clear cut end, so you need some kind of definition on where to stop, and there are many ways to do so. And you should stop estimating thickness by looking at photos. Brightness often masquerades as thickness in photos.
- gjm11 16y agoYes, there are many definitions. None of them, however, gives the result that the Milky Way is flatter than a piece of paper. Not even the (rather silly) one used by the author of the web page you quoted; his numbers are wrong.