The Caldwell Objects

29
present in nearly half of all spiral galaxies.
Images of molecular gas in NGC 5005, made with
the Owens Valley Radio Observatory millimeterwave
array, show three components in the
galaxy's inner 20,000 light-years: a ring (or a pair
of tightly wound arms) with a radius of about
10,000 light-years, a strong central condensation,
and a bar that lies between the two to the
northwest of the nucleus. Gas in the bar
apparently is falling into the nucleus at a rate of
about 50 solar masses per year and will
eventually contribute 200 million solar masses to
a disk surrounding the nucleus. This inflow of
material may someday trigger starburst activity.
NGC 5005 is easy to locate, being only 3°
east-southeast of the fine double star Alpha 1,2
(α 1,2 ) Canum Venaticorum (Cor Caroli) and ½°
due south of a sharp triangle of 6th- and 7thmagnitude
stars (15, 16, and 17 Canum
Venaticorum). Cor Caroli, the triangle, and the
galaxy all fit in the same binocular field. The
galaxy is visible in 7x35 binoculars, though only
with averted vision. Take care when identifying
NGC 5005, because just ½° southeast of it is its
"twin," NGC 5033. NGC 5033 shines at roughly
the same magnitude and has nearly the same
116
dimensions as your Caldwell target; it, too, is
visible in binoculars with averted vision.
Through the 4-inch at 23x NGC 5005 is a nice,
slightly oval haze with a distinct brightening at
the center. At times some fleeting detail appears
in the galaxy's outer envelope. Medium power
brings into view some ill-defined arcs of light,
which, when drawn, should map out NGC 5005's
spiral structure. Higher powers do little to
enhance the view, and I find the galaxy looks best
at 72x. After a prolonged study of the oval haze
at 72x I was able to see an absence of light
running from the northeast to the southwest on
the northern side of the inner lens; it seems to
separate the lens from a hazy arc of light. A little
appendage or hook of light juts to the northeast
from the inner lens, and it is here that the dark
area mentioned above appears to emerge. The
galaxy's southern extremity has a small sharp
boundary, which could be a section of a spiral
arm, perhaps glowing with light from ΗII
regions. Interestingly, Texas amateur Barbara
Wilson — who calls the galaxy "spectacular"
though her 20-inch f/4 reflector at 288x — says
the galaxy's outer extensions are long and faint
and they fade into the background sky with no
Deep-Sky Companions: The Caldwell Objects