Sky and Telescope - April 2016 - 56

OBSERVING

Deep-Sky Wonders
Hickson 44

BOB FRANKE

The peculiar and distorted
structure of NGC 3239,
also cataloged as Arp 263,
can make for a challenging observation - you'll
ﬁnd neither the regular
glow ball of an elliptical
nor the swirling arms of
a spiral. Look instead for
a wedge-shaped glow to
locate this oddity; studying a deep-sky image
may help you ﬁnd the
disturbed arms reaching
southward.

April 2016 sky & telescope

NGC 3239

NGC 3193
NGC 3187

NGC 3190

NGC 3185
SIEGFRIED KOHLERT

My 10-inch reﬂector at 166× adds a stellar nucleus
to NGC 3193, while my 15-inch reﬂector at 216× greatly
prettiﬁes Hickson 44, making features much easier to
discern. The larger scope even teases out part of NGC
3190's dust lane, worn like a dusky ribbon upon the
galaxy's south-southwestern ﬂank.
Interacting galaxies NGC 3227 and NGC 3226 reside
50′ east of Algieba, where my 130-mm refractor at 23×
merely shows a moderately faint glow. At 63× it's evident
that two galaxies exist here. Although the halos blend
together, each harbors a small, distinct, brighter center.
NGC 3227 is oval and tipped south-southeast. NGC 3226
balances atop (north of) its partner, with a halo canted
northeast. Upping the magniﬁcation to 117×, the pair
traverses about 4½′. NGC 3227 sports an oval core with
a prominent, starlike nucleus, and NGC 3226 intensiﬁes
toward its center. NGC 3222 now joins the scene, 13′
west of the duo. This little galaxy appears very dim and
embraces a tiny, feeble nucleus. A faint star ﬂ ickers in
and out of view at NGC 3222's south-southwestern edge.
The remarkably strange galaxy NGC 3239 perches
2.9°° south-southeast of Algieba. My 130-mm refractor
displays a 1¼′ wedge-shaped glow with a distracting
10th-magnitude star on its southwestern edge. The star
makes an isosceles triangle with 12th-magnitude stars
2.4′ west and northwest. The galaxy extends farther
westward when seen through my 10-inch scope at 166×,
with a gauzy, tapering arm reaching out toward the western star. There's a brighter spot on the galaxy's edge,
east of the 10th-magnitude star. My 15-inch reﬂector at
192× brings out a more subtle spot in the galaxy, north
of the star, and a stubby barb of ﬁ lmy light juts southsouthwest from the brighter spot. A ghostly glow dwells
beyond the galaxy about two-thirds of the way from the
10th-magnitude star to a faint star 5.6′ east-southeast. At
216× it becomes a petite north-south oval, the 15th-magnitude galaxy CGCG 94-42 (PGC 30585).

The four gravitationally bound galaxies that comprise compact
group Hickson 44 oﬀer a grand study for visual observers. NGC
3185 presents as an almost face-on spiral, while NGC 3190 is
all but edge-on. NGC 3193 is a classic elliptical galaxy. The dimmest of the group, NGC 3187, is detectable in moderate scopes
only because of its bright bar; you'll need aperture or images to
see the glorious tails of its spiral arms.

Bizarre as my descriptions are, NGC 3239 appears
even more peculiar in deep images, looking something
like a lumpy, mirror-reversed π symbol. The most likely
cause of its tortured appearance is thought to be a galaxy
merger. NGC 3239's weird form has lent it the nickname
the Loony Galaxy.
While galaxies are the main fare when it comes to
deep-sky wonders in Leo, let's ﬁnish with a small dessert - the Frosty Leo nebula, 2.1° north of Omicron
(ο) Leonis. Pointing my 10-inch scope at 166× toward the
correct location, I see a slightly crooked, 15′ line of three
bright stars very unevenly spaced and dressed in shades
of yellow. The nebula sits 12′ south-southeast of the
brightest star and just outside the southern corner of a
3′ isosceles triangle of faint stars. It's very small, bluish,
and roundish with a nearly starlike center. My 14.5-inch
reﬂector at 245× shows that Frosty Leo has a bright oval
core and a relatively thin, fainter halo elongated roughly
southeast-northwest. I estimate a length of 1/3′.
Frosty Leo is a protoplanetary nebula. When an aging
star roughly the mass of our Sun exhausts its hydrogen
fuel, it sheds its outer layers while its core contracts.
The cocoon of cast-oﬀ material reﬂects light from the
star, and we see a protoplanetary nebula. As the collapsing core grows hotter, it eventually warms the nebula
enough to emit its own light, and a planetary nebula is
born. Frosty Leo's name springs from its abundance of
dust coated with crystals of water-ice. ✦

Sky and Telescope - April 2016

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