Sky & Telescope - November 2019 - 55

visible through the 130-mm scope.
It did make an appearance with my
10-inch reﬂector at 299×, and it showed
better at 374× even though atmospheric
turbulence made the stars look furry at
that power.
Let's return to the star 18′ south of
Lassell 1 and look for a slightly dimmer,
orange star 16′ to its southeast. The
planetary nebula Abell 78 sits midway
between these stars. While I was starhopping my way to Abell 78 with my
130-mm scope at 102×, it conveniently
popped into view by a fortunate chance
of averted vision. Only the central star
was evident when looking straight at
the nebula. With a slightly higher magniﬁcation, I detected a fairly large but
vague presence, like a ﬂeeting memory
of moonlight. This fragile apparition is
attended by a faint star off its eastnortheastern edge and a little bunch
of stars near its northwestern edge. A
narrowband nebula ﬁlter makes the
planetary a bit clearer, but an O III ﬁlter
gives a displeasingly dim view in a scope
this small. The 10-inch scope at 166×
reveals a slightly darker area around the
central star.
Images of Abell 78 show a knotty,
east-west ring approximately 1.5′ × 0.9′
within a 2′ faint and slightly oval glow
tilted northwest. The planetary's outer
shell is composed mostly of hydrogen
that once made up the outer layers of

its progenitor star. The knotty ring is
hydrogen-deﬁcient and shines largely
by the light of doubly ionized oxygen
(O III). It contains large amounts of
helium forged in the ﬁres of its parent
star and dredged up to the surface along
with heavier elements by a late ﬂash of
energy from fusion in the star's helium
shell. The star, formerly on its way to
white dwarfhood, was temporarily
reborn as a red giant that entered a second planetary nebula phase and ejected
its hydrogen-depleted envelope into the
previous nebular shroud.
Cygnus seldom comes to mind
when we think of galaxies, but let's
take a peek at NGC 7013, located 2.1°
west-southwest of Zeta Cygni. It's the
second-brightest galaxy in Cygnus,
topped only by NGC 6946, which
straddles the Cygnus-Cepheus border
far to the north.
NGC 7013 is merely a faint, elongated glow through my 105-mm refrac-

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76

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21h 20m

tor at 47×, but the view is much nicer at
87×. The galaxy appears about 2½′ long,
tipped north-northwest, and grows
considerably brighter toward the center.
A 10th-magnitude star dances on its
northern tip, while a faint star guards
its western ﬂank.
Through my 10-inch reﬂector at
213×, NGC 7013 covers 3¾′ × 1¼′ with
a 1½′-long core and a bright nucleus.
The core runs nearly north-south and
shows subtle structure. I think it looks
like a fat, squashed, indistinct Z, but
images indicate that my eye is blending
parts of the galaxy's interior ring and its
nucleus. Can anyone with a large telescope discern this circumnuclear ring?
Now sweep 3.0° east from Lambda
(λ) Cygni to the protoplanetary Egg
Nebula (PK 80-6 1). Such nebulae are
rare because they live for an astronomically brief time. When an aging star
a little more massive than our Sun
exhausts its hydrogen fuel, it sheds its

21h 10m

21h 00m

20h 50m

20h 40m

i
74

+40°

m

Baby Dumbbell

61
72

+38°

o
70

q The components of Lassell 1 are labeled

Egg Nebula

here by their Washington Double Star Catalog
designations. The field is 15′ wide, and the
"false double" described by the author is in the
upper-left corner.

+36°

7063

p
+34°

POSS-II / STSCI / CA LTECH / PA LO M A R OBSERVATORY

CYGNUS

B

E

F

A
D

C

h

¡
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Lassell 1

+32°

Abell 78

G

Veil Nebula

c

7013

52

+30°

sk yandtele scope.com * N OV E M B E R 2 019

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Sky & Telescope - November 2019

Table of Contents for the Digital Edition of Sky & Telescope - November 2019
