ASTRO: The surprising M 40 field

M40 is simply the double star Winnecke 4. The separation has been
steadily increasing since Winnecke first measured it at 49.2" in 1863 at
a position angle of 88 degrees. Hipparcos in 1991 said 52.8" at 77
degrees. Intermediate measurements show the pair to be separating on a
straight line so they are a line of sight pair. There seems to be some
discrepancy about their spectral color. Lick Observatory's catalog
shows them as G0 and F8 while Brian Skiff says K0III and G0V.
Unfortunately my color data is severely distorted by clouds, especially
during the red frames. I tried on a second night for new red data only
to have clouds again create a problem. Thus I'm not sure about my
colors. I did push them too but I seem to see a late G and early F.
Looking at other photos on line I see the few color ones showing white
and slightly blue though the Sloan Survey image would appear to agree to
Brian Skiff's K and G classification. I'm likely too blue with the
hotter star.

The main reason for imaging it was I'm trying to get color digital
images of all M objects north of 15S. So was going to make a quicky of
it but when I saw the two nice galaxies appear in the framing shot I
decided to move to a mid point between them and use my normal exposure
time. As mentioned, clouds hurt the color data. Another I should revisit.

The barred spiral, NGC 4290 reminds me of "The Eye" galaxy I posted in
early May, NGC 3646 in that it has a large ring surrounding a rather
normal galaxy, a barred spiral in this case. The inner ring is somewhat
distorted with the western side nearly linear rather than circular in
shape as the eastern half is.

Assuming a distance of 140 million light-years and a diameter of 2.02
minutes it is only 80,000 light years across, much smaller than NGC
3646. NED and the NGC Project class it as SB(rs)ab: with HII.

The spiral to the west is NGC 4284. It is somewhat further away; 200
million light-years by redshift and a bit further, 225,000 by the
average of Tully-Fisher measurements though a measurement by IRAS agrees
to the redshift value. At first glance it appears smaller in angular
size than NGC 4290 but when the drawn out faint arm pointing toward NGC
4290 is considered it is actually larger at nearly 2.8 minutes. That,
using the 200 million light-year distance gives a size of 160,000
light-years or twice that of NGC 4290. It is classed as Sbc by both NED
and the NGC project. Except for the faint drawn out arm it is a pretty
normal looking, if very large spiral galaxy.

There's a really flat galaxy just under a bright star toward the bottom
of the image below NGC 4290. I was hoping to find something on it but
NED fails to pick it up and also fails to pick up a much fainter smudge
beside it. These are marked by a question mark. Also, a very blue
smudge of a galaxy just above a very blue star-like galaxy is also
missing from the catalog though the blue star-like one is listed.

The image has several very blue quasars as well.

14" LX200R @ f/10, L=4x10' RGB=2x10' STL-11000XM, Paramount ME

Rick
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