 NGC
1893 is another overlooked open cluster in Auriga. The nebula
it is embedded in, IC 410, is often photographed but rarely observed
visually even though it is not that difficult. Walter Scott
Houston noted that NGC 1893 "contains a conspicuous Y pattern
formed by four 8th magnitude stars." He goes on to
note reports that the cluster appears embedded in a haze of
unresolved stars and suggests that the haze may actually be
attributable to the surrounding IC 410 nebula. In fact, IC 410
has been detected in telescopes as small as 12 inches without a
filter and I was easily able to discern a faint, broad haze in my
18-inch. But it is the availability of UHC and OIII filters in
recent years that has really unlocked this treasure.
 In
my 18-inch with OIII filter in place a large, diffuse haze became
quite readily apparent. The brightest region appears
surrounding the stars that form the northwest portion of Scotty's
"Y" (lower left in diagrams here). A broad swatch of
haze turns from here to roughly follow the pattern of stars
southward, only to turn once again, this time to the east. The
result is a large, broad, Z-shape. This shape can be seen
faintly in the image here if you follow the whiter portions of the
nebula, ignoring the deeper reds. The H-Beta filter also
brought out the nebula, but not as well as the OIII. Others
have reported easily seeing the nebula in a 10-inch scope with UHC
filter in place. I would not be surprised if the nebula could
be detected in instruments as small as 6-inches from a dark site
with a UHC filter.
The stars
of this cluster are all very young, having only been recently formed
from the cloud complex that we see as IC 410. In terms of the
lives of stars these are all newborns, only 3 weeks removed from the
womb. In high resolution images two sets of gas streams can be
seen in the northeast portion of the cluster. The massive,
hot, newborn stars of the cluster are literally blowing the gas and
dust away from the region. But the presence of a dense region
of gas can block the wind leaving a gas "shadow" behind
it. These two "shadows" can be seen in the lower
right of the image (enlarged in the image on the left). I have
not been able to find any observations of these streamers and was
not aware of them when I last observed this region. I wonder
if they might be visible under higher magnification, perhaps with an
H-Beta filter in place?
The field in an 6-inch f/8 at
50x. North is down and east is to the right. |
