Friday, November 25, 2005

iPod iChing - universal birth functions

It is friday, it is time for lazy lite late night blogging...

Oh, mighty iPod. Is the Initial Mass Function of main sequence stars really well approximated by a universal power law (with a break at the low mass end)? Or, excluding of course the metal free first stars, are there significant differences in the IMF depending on environment of composition?

Woosh goes the randomizer. Woosh.

  • The Covering: Unhappy Birthday - Smiths

  • The Crossing: The Crawdad Song - Twin Sisters

  • The Crown: Science Fiction/Double Feature - Rocky Horror Picture Show

  • The Root: For You - Tracy Chapman

  • The Past: Moon Hop - Derrick Morgan

  • The Future: Can't Stand Losing You - Police

  • The Questioner: Torture - Cure

  • The House: Cuna - Julian Bream

  • The Inside: The Wheels on the Bus - Twin Sisters

  • The Outcome: Sulk - Billy Bragg

For completists: #11 is The Lemon Song - Spilverk Þjóðanna and #12 Yankee Doodle - Twin Sisters.

Hm, so my take is that the question, despite my care is slightly ill posed, and the IMF concepts is an artificial projection seeking to simplify a more complex reality.
But, for those who care, there are two modes of star formation, excepting "first stars", and I am in trouble for raising the question.
We'll keep going, and stars will keep forming without regard for oversimplifications of theorists.

As always, the Key as explained by Sean


Blogger Adam Solomon said...

Yeah, it seems (from the POV of someone not-very-well-read on the subject) that a power law to accurately describe the IMF is at least imperfect. But hey, the universe can surprise ya ;) I know some people working on luminosity functions (not mass functions, since these are for L and T dwarfs), but I don't think they're trying to describe it using any kind of strict mathematical function, just a simple histogram (I think?). I wonder if that might just be the way to go about describing the IMF, way in the future.

Hmm, I wonder, if we could get a mass function for a sample of x parsecs around us, just a histogram counting how many objects we find of each mass, assume it to be applicable to the rest of the universe (actually, that's a pretty crappy assumption, isn't it?) and then derive the IMF backwards. Although I guess that would require an idea much better than the one we have today of how many stars a supernova will form, at what mass distribution, etc., given the mass of the progenitor star...or maybe I'm just crazy and have way too much time on my hands when walking through the streets of NYC...hmmm...

11:26 AM  

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