Holiday
32. cheer
of galaxy M74
In this Hubble image of the galaxy M74 we can also see a smattering of
bright pink regions decorating the spiral arms. These are huge, relatively
short-lived, clouds of hydrogen gas which glow due to the strong radiation
from hot, young stars embedded within them; glowing pink regions of
ionized hydrogen (hydrogen that has lost its electrons). These regions
of star formation show an excess of light at ultraviolet wavelengths and
astronomers call them HII regions.
Credit: NASA, ESA, and The Hubble Heritage (STScI/AURA)-ESA/Hubble
Collaboration
“By far my favorite image (and I know I’m
biased here) is the Bullet Cluster image*.
I was directly involved with the research,
and with a powerful combination of Hubble
and Chandra we have shown that dark
matter exist, and have directly measured
its properties for the first time. Dark matter,
mysterious stuff that makes up 25% of the
universe turned out to be very anti social.
Or in the words of Sean Caroll, ‘Most of the
Universe can’t even be bothered to interact
with you.’ And that just means that it is
absolutely fascinating.”
— Marusa Bradac
Associate Professor
University of California Davis
* http://hubblesite.org/newscenter/archive/releases/2008/32/