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M23

Messier 23 (M23) is an open star cluster in the southern constellation Sagittarius. It is designated as the 23rd object in the Messier catalog, which groups diffuse star clusters and other fuzzy patches that were identified in the 18th century by Charles Messier. M23 is observable with small telescopes or good binoculars and appears as a loose, hazy concentration of stars rather than a tight, spherical cluster.

Location and characteristics are best described in the context of the Milky Way. The cluster lies near

Age and significance vary in studies of M23. Estimates place the cluster in the range of hundreds

the
plane
of
the
Galaxy,
in
a
rich
star
field
toward
Sagittarius,
and
is
part
of
the
Milky
Way’s
disk
population.
It
is
situated
at
a
distance
of
several
thousand
light-years
from
the
Sun
and
spans
a
few
tens
of
light-years
across.
Its
stellar
content
includes
dozens
to
hundreds
of
member
stars,
with
a
mix
of
brighter,
visible
stars
and
many
fainter
companions.
The
overall
appearance
is
that
of
a
moderately
rich,
loosely
bound
cluster
with
a
relatively
low
central
density
compared
with
some
younger
clusters.
of
millions
of
years
old,
making
it
older
than
the
most
recently
formed
open
clusters
but
still
relatively
young
on
a
galactic
scale.
M23
is
used
in
discussions
of
stellar
evolution
and
cluster
dynamics,
including
analyses
of
stellar
populations,
mass
segregation,
and
the
interaction
between
clusters
and
the
Galactic
background.
Its
visibility
and
accessibility
continue
to
make
it
a
common
target
for
amateur
observers
and
a
reference
point
in
discussions
of
open
clusters.