2015년 2월 8일 일요일

[New post] Astronomy Photo of the Day: 2/8/15 — NGC 7673

New post on From Quarks to Quasars

Astronomy Photo of the Day: 2/8/15 — NGC 7673

by Jaime Trosper
NGC 7673
Image Credit: European Space Agency, Nicole Homeier (European Southern Observatory and University of Wisconsin-Madison)
Meet NGC 7673: a discombobulated galaxy that shows chaos can be rather beautiful when the right circumstances present themselves; This particular example can be found approximately 150 million light-years from Earth in the Pegasus constellation.
The image you see above is a composite, put together using 3 images taken by the Hubble Space Telescope's Wide Field Planetary Camera 2 all the way back in 1996 and 1997. According to NASA, the exposure time for a red filter was 800 seconds, 1,200 seconds for the green filter, and 2,300 seconds for the blue filter.
Each filter allows astronomers to see a distinct part of the galaxy. For instance, the blue light signifies the presence of star formation activity; in NGC 7673's case, each patchy region contains a collection of young, hot stars — numbering in the hundreds, maybe thousands. Believe it or not, these stars have accumulated into spiral arms — albeit nontraditional ones — that weave a tangled web, indeed.
That's not the only fascinating tidbit of information. Astonishingly, the youngest among them are so energetic, they individually radiate 100 times more ultraviolet radiation than the Tarantula Nebula: an H II region in one of our galaxy's companions, the Large Magellanic Cloud (LMC).
NGC 7673 isn't the only galaxy Hubble captured in this field of view either; in fact, two other galaxies can also be seen — one on the left and one on the right (the bright pinpoint of light in the upper-right comes from a star in the Milky Way). Both are much more distant than NGC 7673, hence their reddish coloring.
See a larger image here.


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