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Denebola1214
16171321COMA
BERENICESLEO
NW5°Melotte 111
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1617132158 ASTRONOMY • APRIL 2021
BINOCULAR UNIVERSE
I’ll admit it: I am an addict. I am hooked on
vintage astronomy books. One of my favor-
ites is Astronomy With an Opera-Glass by
Garrett P. Serviss, first published in 1888. Serviss, a
newspaper reporter by trade, was a prolific author of
the late 19th and early 20th century. He wrote nine
astronomy books for backyard stargazers, as
well as six lesser-known science-fiction
books. His words describing this month’s
target are a perfect way to introduce one of
my favorite springtime sights:
“The three [stars], Denebola, Spica, and
Arcturus, mark the corners of a great equilat-
eral triangle. Nearly on a line between
Denebola and Arcturus, and somewhat nearer
to the former, you will perceive a curious
twinkling, as if gossamers spangled with
dew-drops were entangled there. This is the
little constellation called Berenice’s Hair.”
Historically, Berenice II was queen of Egypt, mar-
ried to Ptolemy III Euergetes. Around 240 B.C., after
her husband left to fight a particularly dangerous battle
against the Seleucid Empire in western Asia, Berenice
vowed to the goddess Aphrodite that if Ptolemy
returned safely from battle, she would cut off her f low-
ing hair and place it in the goddess’ temple. He did, so
she did. But the hair mysteriously disappeared.
Thinking quickly on his feet, their court astronomer
Conon calmed the royal couple by pointing toward a
hazy glow in the sky between Denebola and Arcturus.He announced that the mist seen faintly by eye was
actually Berenice’s hair, transformed by Aphrodite and
placed among the stars.
Berenice’s Hair, more formally known as
Coma Berenices, is a faint constellation by eye, com-
posed of only three modest naked-eye stars set in a right
triangle. But what catches our eyes under darker skies
is also a faint glow west of those stars. No, that misty
glow is not the transfigured tresses of the ancient
queen’s hair. That glow is actually an open star cluster
lying 280 light-years from Earth.
The Coma Star Cluster, known more formally as
Melotte 111, often goes unnoticed through telescopes
but is perfect for binoculars. That’s because the cluster
spans 5° of sky, far more than a telescope can drink in
at once. Its stars are also quite scattered, making it dif-
ficult to appreciate the cluster even with a careful
telescopic scan.
According to Star Clusters by Brent Archinal and
Steven Hynes (Willmann-Bell, 2003), over 270 stars
populate the Coma Star Cluster. Of those, about 40
shine brighter than 10th magnitude. Many are easily
within range of pocket binoculars and a half-dozen
even break the naked-eye barrier under dark skies.
Although I can’t make out individual stars by eye
from my suburban backyard, I do get a “mystical” sense
to the east of Denebola (Beta [β] Leonis). When I raise
my old 7x50 wide-field binoculars its way, the
Coma Star Cluster immediately pops into view.
A lt hou g h it i s not a s ja m-packed w it h st a rs a s some open
clu sters i n t he su m mer or w i nter sk ie s , t h i s i s a lway s one
of my first stops when I head out this time of year.
The first thing that strikes me is the cluster’s distinc-
tive shape. Those five brightest stars are arranged in
a rc s a nd l i ne s t hat col lec t ively rem i nd me of a V-shaped
skein of northward-f lying geese. Others see a lower-
case Greek lambda (λ) or an inverted V.
The cluster’s brightest star is not
Gamma (γ) Comae Berenices, despite its
prominent position at the northern edge of
the cluster. Although it adds some color to
the scene, Gamma, an orange type K star, lies
in the foreground 170 light-years away. The
brightest true cluster stars include 12, 13, 14,
16, and 21 Comae Berenices.
Several stellar pairings highlight the
Coma Cluster. Of t hese, 17 Com, just east of
the cluster’s center, is the most striking. Even
the smallest opera glass will have no trouble
resolving 17’s 7th-magnitude companion, found 2.5' to
its west-southwest.
Do you have a favorite star cluster or some other
binocular target that you enjoy revisiting? Drop me a
line in care of my website, philharrington.net, and tell
me about it.
Until next month, remember that two eyes are better
than one.Binocular users can make the most of this cluster.
A hair-raising
cluster
The Coma Star
Cluster once
represented the tail of
Leo, before Ptolemy
III renamed it for
Queen Berenice II’s
sacrifice of hair.
ASTRONOMY: ROEN KELLYThis is
always one
of my first
stops when
I head out
this time of
year.
BY PHIL
HARRINGTON
Phil is a longtime
contributor to
Astronomy and the
author of many books.BROWSE THE “BINOCULAR UNIVERSE” ARCHIVE AT
http://www.Astronomy.com/Harrington