The qualities and behavior of dark matter, the invisible "glue" of the universe, continue to be shrouded in mystery. Though galaxies are mostly made of dark matter, understanding how it is distributed within a galaxy offers clues to what this substance is, and how it's relevant to a galaxy's evolution. This is one of those "enlightening moment" cases, based on a deeper look at some rather old Hubble data -- from NASA's Hubble team -- do read it all:
. . .To learn about dark matter within a galaxy, scientists can look to its stars and their movements that are dominated by the pull of dark matter. A common approach to measure the speed of objects moving in space is by the Doppler Effect – an observed change of the wavelength of light if a star is approaching or receding from Earth. Although this line-of-sight velocity can provide valuable insight, only so much can be gleaned from this one-dimensional source of information.
Besides moving closer or further away from us, stars also move across the sky, measured as their proper motion. By combining line-of-sight velocity with proper motions, the team created an unprecedented analysis of the stars’ 3D movements.
"Improvements in data and improvements in modeling usually go hand in hand," explained Roeland van der Marel of STScI, a co-author of the paper who initiated the study more than 10 years ago. "If you don’t have very sophisticated data or only one-dimensional data, then relatively straightforward models can often fit. The more dimensions and complexity of data you gather, the more complex your models need to be to truly capture all the subtleties of the data. . . ."
This is excellent new work. And this entry puts us back on the footing of good, scientific space ju ju -- here in our little shop.
I will predict a very "locked down" Milwaukee -- and perhaps even a short form convention, this week, for the GOP. Onward.
नमस्ते
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