The Caldwell Objects

egion's size and mass extreme when compared
with those of other Η II regions. HD 199579 is
still a contender for an energy source — but it's
not the only one. In a 1980 Astronomy and
Astrophysics report Thorsten Neckel (Max Planck
Institute for Astronomy, Germany) and his
colleagues announced their discovery, at nearinfrared
wavelengths, of an extremely reddened
star at the center of the dust lane that divides the
North America — Pelican Nebula complex. The
scientists con-
The Caldwell Objects
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cluded that this star is a
major source of illumination
for both nebulae.
Other ionizing
sources have been
found since; they appear
to be pre-mainsequence
stars with a
wide range of masses.
To the naked eye the
North America and
Pelican complex stands
out as an enhanced
region in the Cygnus
Milky Way. The North
America Nebula itself
spans more than 1½°. If
we accept a distance of
1,800 light-years, the
nebula spans nearly 50
light-years of space. Its
glow is not powerful
enough for us to see the
entire continental outline
without optical aid;
the gaseous regions representing
Mexico and
Florida are the nebula's
weakest parts by far. As
I see it, the naked-eye
view is more like that of
a box that has been kicked by a mischievous
child. But any pair of small binoculars will bring
out the missing features. At 23x the 4-inch
Genesis is the perfect instrument to show the
North America Nebula's full grandeur, as its
nearly 3° field of view fully encompasses the
object with room to spare. And at 23x the nebula
is a most rewarding sight. Countless suns are
scattered across a pale green glow, looking like
scintillating gems emerging from a sheet of
melting ice.
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