M
ost deep-sky hunters
associate Leo with
galaxies … and so
they should. Although
the celestial Lion has
other wonders (espe-
cially Regulus and Gamma Leonis, two
regal double stars), we can enjoy them on
our way to more exotic galaxies.
Most of these galaxies can be seen read-
ily through modest-sized apertures, but
some will require much greater apertures.
Others still are best appreciated by involv-
ing the imagination to see the delicate dra-
mas unfolding in and around them in
wavelengths that extend beyond the eye’s
visual range. After all, astronomy is half
science, half imagination.
I hope the latter exotics will inspire
astroimagers to capture these objects and
their demanding details and bring them to
light so the rest of us can enjoy them as
they truly are.
Hidden dwarfs
Leo harbors a fine selection of dwarf galax-
ies, many of which can be enjoyed by
observers using telescopes both large and
small. But we’ll start with a visual chal-
lenge: the 10th-magnitude dwarf spheroidal
Leo I.
Astronomy Senior Editor Michael E.
Bakich succinctly summarizes the situa-
tion: “Easy to find, hard to see.” The galaxy
lies only 20' north of Regulus (Alpha [α]
Leonis), but its light spreads across 12' by 9'
of sky. (That’s comparable in size to NGC
205, but two magnitudes fainter and with
no core!) Add in glare from Regulus, and
you’ve got a wonderful visual challenge.
Hints: Use a wide-field eyepiece that
provides moderate magnification (70x),
push Regulus out of the field of view, and
gently tap the tube as you look for a dim
and uniform carpet of ethereal light against
a bleak background of stars. At a distance
of 800,000 light-years, Leo I may be the
farthest satellite system orbiting our galaxy.
Regulus itself is a multiple star system
that can be seen with binoculars and tele-
scopes, and offers a secret challenge. This
glistening 1st-magnitude jewel shines with
a dazzling light. An 8th-magnitude “violet”
(a color-contrast illusion at low power)
companion (B) lies 3' to the northwest; B is
actually an orange dwarf. If you are using a
large aperture (12 inches and greater), don’t
stop there. Use 300x or more on a night of
54
A ST R O N O M Y • MAY 2018
excellent seeing to look for that orange
dwarf’s 13th-magnitude red dwarf com-
panion (C) 2.5" to the east. The greater the
magnification, the greater the apparent
separation, and the greater your chances
are to see faint objects.
Yet there’s more! Even small-telescope
users can search for a 12th-magnitude line-
of-sight companion (D) 3' due west of
Regulus — a sneaky little star often missed
by the casual viewer. What you can’t see is
the spectroscopic object, speculated to have
once been a luminous giant greater than
Regulus but is now an Earth-sized high-
density white dwarf star of 0.3 solar mass.
Take a deep breath before you head to
our next challenge, Leo III (Leo A). This
enigmatic dwarf galaxy is one of the most
Below: Two odd galaxies, NGC 3226 and
NGC 3227, float in Leo as they gently lock
in a tidal embrace. NGC 3227 (right) is the
somewhat brighter barred spiral in this
interacting pair. Elliptical galaxy NGC 3226
lies to its left. ROBERT LOCKWOOD