66 ASTRONOMY • APRIL 2020BINOCULAR UNIVERSE
The area south of
the Big Dipper’s
handle is occu-
pied by the constellation
Canes Venatici, supposedly
a pair of hunting dogs. Last
month, I likened the form of
Canis Minor the Little Dog
to a hot dog, since it is cus-
tomarily drawn from just
two stars. Unfortunately, we
can’t do much better here.
As you can see from this
issue’s Star Dome map
(pages 38-39), the figure of
Canes Venatici is also cre-
ated from just two stars.
The brighter of the pair,
Alpha (α) Canum Venaticorum, is known by the
proper name Cor Caroli. Cor Caroli translates as
“Charles’ Heart.” Most authorities agree that the name
was coined in 1660 by Sir Charles Scarborough, physi-
cian to King Charles II of England. But exactly which
Charles’ heart was being memorialized is not well
established. Some say the intended honoree was King
Charles I of England, who was beheaded in 1649 during
the English Civil War. Others say it refers to
his son, Charles II, who restored the English
monarchy in 1660.
Because Cor Caroli shines at only 3rd
magnitude, it does not stand out well to the
e ye a lone. Hu nt it dow n w it h bi noc u la rs a nd
you’ll be looking at the prototype of a special
c ategor y of spec t r a l t y pe A su ns cla s si f ied a s
“magnetic stars.” Studies show that it is abun-
dant in mercury and silicon, as well as some
rare elements, like europium.
A 6th-magnitude, type F yellow-white
companion orbits Cor Caroli, separated by 19". That’s
likely too close to resolve through most handheld
binoculars, but I can just detect both through my
tripod-mounted 16x70s. Give it a try and let me know
how you make out.
Due east of Cor Caroli are 15 and 17 Canum
Ve n at i c o r u m. Toget her, t he y ma ke a n e a s y double st a r
to admire through low-power binoculars. Both appear
almost identical, with the eastern star (15 Canum
Venaticorum) shining at magnitude 6.3, while
17 Canum Venaticorum glows at magnitude 6. Both
g low pu re wh ite. I n re a l it y, howe ver, t hei r a l l ia nc e i s ju stcircumstantial. Estimates place 17 Canum Venaticorum
at 202 light-years from us, while 15 Canum Venaticorum
is at 1,144 light-years.
Turning our attention to the constellation’s Beta (β)
star, we come to Chara, the Greek word for “joy.”
Shining only at magnitude 4.3, Chara is spectral type
G0, a yellow dwarf main sequence star that is often
referred to as a solar analogue. It’s only 100 kelvins
hotter, 18 percent more luminous, and 4 percent larger
than our Sun. It’s also believed to be about 2.5 billion
yea rs older. In ot her words, when we look at Cha ra, we
are essentially looking at our future Sun from a distance
of just over 27 light-years.
Cor Caroli and Chara are separated in our sky by 5°,
close enough to squeeze into the same 10x binocular
field. Place them both in view on either side of the field.
Just south of an imaginary line connecting them, you’ll
see 6th-magnitude 10 Canum Venaticorum, another
type G0 star. But to the line’s north, about 3° due east
of Chara, you might also spot a small, faint blur of gray-
ish light. That’s the 8th-magnitude spiral galaxy M 94.
Nicknamed the Cat’s Eye Galaxy or Croc’s Eye Galaxy
for its appearance in photographs, M94 is seen nearly
face-on from our perspective. As spirals go, it is small,
a bit more than half our Milky Way in diameter. Despite
its modest size, M94 packs a punch. It is also classified
as a starburst galaxy, where internal density waves are
compressing interstellar matter into protostars more
vigorously than in t y pica l spira ls.
Although it strikes me as a little fainter than M94, M63
(the Sunf lower Galaxy) is also within reach of 35mm to
50mm binoculars. To find it, place Cor Caroli
in the southwestern edge of your binocular
field and then glance to the opposite side. You
should see four stars set in a distinctive right
triangle. M63 is just 1° north of
19 Canum Venaticorum, the star at the trian-
gle’s right angle. Look for a thin sliver of light
tilted east-west. Like M94, M63 is classified as
an Sb spiral galaxy. The marked difference in
appearance is owing to its angle of presenta-
tion. While M94 is seen virtually face-on, M63
is tilted at a much narrower angle. Although
they are no more than a binocular field apart in our sky,
M63 is substantially farther away, some 26.7 million light-
years to M94’s 17.3 million light-years. Under a dark sky,
you might notice a faint star at the western tip of M63.
Although it’s often mistaken for a supernova within M63,
that star is just a photobomber from the Milky Way.
Thoughts? Comments? Contact me through my
website, philharrington.net. Until next time, remember
that two eyes are better than one.Canes Venatici the Hunting Dogs offers rare binocular treats.
Going to the dogs
The bright galaxy
M63 in Canes
Venatici appears in
binoculars as an oval
smudge with a
slightly brighter
center. R. JAY GABANYThe figure
of Canes
Venatici is
created
from just
two stars.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