The Caldwell Objects

RA: 03 h 19 m 48 s
Dec: +41° 30.7'
Mag: 11.9
Dim: 3.2' x 2.3' SB: 13.9
Dist: 230 million light-years
Disc: Heinrich Louis d'Arrest, mentioned in the 1867 Siderum
Nebulosorum Observationes Havnienses
H ERSCHEL: None.
GC: None.
NGC 1275 is THE BRIGHTEST AND MOST CEN-tral
member of the Perseus Cluster of galaxies, a
dense nest of some 12,000 systems roughly 230
million light-years distant — four times farther
from us than the far better known and easier-toobserve
Virgo Cluster. To see the Perseus
Cluster, which also is known as Abell 426, we
must peer through a thicket of stars and dust in
the Milky Way's outer reaches. By penetrating
this thicket with radio telescopes, astronomers
have discovered that NGC 1275 and its family are
cutting through a fog of intergalactic material;
this is evidenced by long "wakes" of plasma
trailing several of the cluster's galaxies. The
intergalactic fog was probably ejected over the
eons by the active nuclei in the cluster's feistier
systems, or torn free from spirals passing near
the cluster's dense core.
As with many spherical galaxy clusters rich
in energetic ellipticals, the Perseus Cluster is also
a strong emitter of X-rays. Four-fifths of the
cluster's X-ray energy emanates from gases
spread throughout the 3-million-light-year-wide
cluster; the remainder comes from NGC 1275
itself.
NGC 1275 long has been known as a strong
source of radio emission. It is listed in the Third
Cambridge Catalogue of radio sources as 3C 84;
early radio astronomers referred to it simply as
Perseus A. In addition, Carl K. Seyfert included
it in his 1943 list of galaxies that display exceptionally
bright or starlike nuclei. In photographs
taken with the powerful 200-inch
The Caldwell Objects
NGC: Faint, small in angular size.
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telescope on Palomar Mountain, NGC 1275's
nucleus appears very tight, almost stellar.
The galaxy's overall white-light appearance is
that of a lenticular or elliptical system. A black
"scratch" can be seen zigzagging across the
galaxy's northern halo, and deep red-light images
show a system of twisted filaments radiating in
all directions. In a humorous way, these filaments
suggest a child's drawing of an explosion in a
spaghetti factory. The galaxy's filamentary
"noodles" are fleeing into space with velocities on
the order of 2,400 km per second. The enigmatic
"scratch" has two parts: a bright streak that juts to
the northwest before cutting sharply to the north,
and a disjointed arc of matter that hugs the
galaxy to the north, spirals to the east, then
curves gently south. Bright ΗII regions and dark
dust patches line both features. If we can free our
imaginations and see this galaxy in three
dimensions, the "scratch" looks like the flailing
arms of an unseen spiral galaxy whose body has
sailed obliquely into NGC 1275's "mouth." That
scenario, in fact, is just what radio data suggest.
As early as 1957 Walter Baade and Rudolph L.
Minkowski proposed that NGC 1275 is an interacting
pair of galaxies. The bright compact body
appears to be that of an elliptical or lenticular
galaxy, while most of the dust patches seem to be
associated with the arms of a spiral system
moving through NGC 1275 at a speed of 3,000
km per second. Tidal interactions have distorted
the spiral's shape and may have ripped free the
curved "tail" of stars to the east.
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