44 M37
While Charles Messier found M37 (along
with M36) on Sept. 2, 1764, he wasn’t the
first to discover this cluster. Giovanni Battista
Hodierna (sometimes spelled Odierna)
had noted it — along with M36 and M38 —
110 years earlier in a book on cometary and
non-cometary celestial objects.
The premier open cluster in Auriga,
M37 is the richest of the Charioteer’s three
Messier clusters, with about 150 stars
brighter than magnitude 12.5 packed in a
region 24' across. Its integrated magnitude
is listed between 5.6 and 6.2 — bright
enough to see with the naked eye. Look for
it outside of the pentagonal outline of the
constellation. If you draw a line between
Theta (θ) Aurigae and Beta (β) Tauri, M37
lies slightly northeast of its midpoint.
Auriga lies on the galactic plane in the
opposite, or antipodal, direction of our
galaxy’s nucleus, located in Sagittarius.
Sitting at the inner edge of the Milky Way’s
Perseus Arm, M37 is 4,500 light-years
away. By comparison, the intrinsically more
luminous Owl Cluster (NGC 457; see #55) is
only slightly fainter in apparent brightness,
but some 3,400 light-years more distant, in
the outer Perseus Arm.
M37 is visible as a nebulous patch in
binoculars and small scopes. In a 3-inch
scope, the brightest stars are apparent;
with increasing aperture, more stars
become visible. In a 6-inch telescope at low
power, you may see some 25 stars. With
higher magnification in the same scope,
the number increases to more than 40. The
fainter members crowd the field of view in
large instruments, adding to the already
rich foreground stars.
At an estimated 300 million to 500 million
years old, one might consider this cluster on
the older side of middle age. Compare that to
its less mature neighbors: M38 is 220 million
years old, while M36 is an even younger 25
million years old. M37 has orbited the Milky
Way twice in its lifetime, yet it still maintains
a dense pack of members. About a dozen of
its stars have evolved into red giants, so look
for some color sprinkled in the mix. — A.G.
45 NGC 1365
Most observers would admit that, out of all
galaxies, barred spirals make the best targets
for amateur telescopes. That said, it’s a pity the
best example of a barred spiral — NGC 1365 —
languishes in the nearly invisible constellation
Fornax the Furnace.
As galaxies go, NGC 1365 is bright: magni-
tude 9.4. It’s also not tiny, measuring 8.9' by 6.5'.
It lies some 60 million light-years away and
is part of the Fornax Cluster of galaxies, the
second-richest nearby grouping of such objects
(topped by only the Virgo Cluster). The Fornax
Cluster boasts more than 2,600 members.
Astronomers using the Hubble Space
Telescope revealed that NGC 1365 feeds material
into its central region, igniting massive bursts
of star formation and growing its central bulge.
The material also feeds a 2-million-solar-mass
supermassive black hole in the galaxy’s core.
Although it’s bright, NGC 1365 isn’t that easy
to find if your telescope doesn’t have a go-to
drive. To locate it, first find a triangle of three
faint stars that lie 7½° south-southeast of mag-
nitude 3.9 Alpha (α) Fornacis: magnitude 6.4
Chi^1 (χ^1 ), magnitude 5.7 Chi^2 (χ^2 ), and magnitude
6.5 Chi^3 (χ^3 ) Fornacis. From Chi^2 , which is the
brightest, move 1.3° east-southeast.
A 4-inch scope at a dark location will reveal
NGC 1365’s bar and brighter central region. With
an 8-inch or larger instrument, you can crank
up the power to also see the arms. The northern
one, which starts at the west end of the bar, is
brighter. The other is a bit blotchy because it
contains huge star-forming regions. — M.B.DAN CROWSON