Beyond wrote:I like M66. It's more colorful, and the red part resembles a horizontal -5-, or a sloppy -S-. Could you really call an object that's so full of dust, unsloppy??
Beyond, you're right! The red part in M66 really does look like one large big red "S" or a number "5", possibly somewhat sloppy!
The reason why the central dust lane in M66 looks so red is because the photographer, Bill Snyder, has taken care to extract as much Hydrogen Alpha (Ha) information as he possibly can from M65 and M66. The red color mostly traces hydrogen that has been ionized and made to glow red. Hydrogen can be ionized by different processes, but in the case of M66 (as well as in the Milky Way) it mostly happens when newborn hot stars ionize the dust clouds from which they were born. Therefore Ha emission is an excellent tracer of recent star formation.
And as Bill Snyder so eloquently demonstrates, the major dust lane of M66 is really full of Ha light and star formation! We may also note the distorted shape of M66, which may have helped "slosh the gas together" and precipitate star formation.
By contrast, look at M65! There are no signs of any obviously red patches anywhere in that galaxy, although there may be, possibly, some marginally pink regions. Nevertheless, it is clear that there is extremely little star formation in M65. Note that there appears to be a large ring of dust surrounding the inner bulge of M65, and note, too, that there might possibly be a dusty bar crossing the inner bulge and bridging the large ring. Note that there are some bright and marginally blue patches in the ring at 2 o'clock, which are probably some relatively young clusters. But they are not young enough to produce emission nebulae.
This is an excellent picture with brilliant color information!
Ann
M65 and M66
