Arp 154 (NGC 1316)
Arp 154 is in the class Disturbed with Interior Absorption. The
Atlas note is "For[nax] A radio source. Short exposure to show
absorption in center." My image is not short, and does not show the
absorption well but the detail image of the core region has been processed to
show it better. It's on the north and NW sides. In general, my
images don't show absorption nearly as vividly as the Atlas images do.
Part of that, of course, is the difference in resolution of the telescopes.
What is likely more important, however, is the high blue sensitivity of Dr.
Arp's plates versus the high red and IR sensitivity of my CCD chip.
Absorption is almost always caused by dust and dust absorbs short wavelength
emission, reemitting it as red or IR light. It won't be as dark and stand
out as much on a CCD image. I plan to
try reimaging some of these galaxies with a blue filter and IR blocker. If
my theory is correct, that should show the absorption much better.
Arp 154 (NGC 1316) is the large galaxy to the south. The smaller galaxy to the north is NGC 1317, and is not part of the Arp field.
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