Sky and Telescope - January 2016 - 65

A MIGHTY JET
A jet of gas and
dust, visible here
to the northwest
(right) of M87,
blasts from the
black hole at the
center of the galaxy at nearly the
speed of light; it
extends at least
5,000 light-years
from its source.

M87

NGC 4783

RICHARD JAKIEL (2)

NGC 4782

NEAR
COLLISION
Ellipticals NGC
4782 and NGC
4783 started
life as separate
objects, but a
high-speed near
collision left
behind a loosely
bound interacting
system resembling a dumbbell
in the eyepiece.

NGC 4874
NGC 4889

BOB FRANKE

the massive elliptical. To ﬁnd NGC 1275, start at Beta
(β) Perseus (Algol), and star-hop 2°° to the east-northeast
through the Perseus Cluster. Measuring 2′ × 1.5′, it takes
a fairly large scope to detect some of the irregularities in
its structure and appearance.
As we move toward springtime in the Northern
Hemisphere, make plans to expand your observations
to include the Coma and Virgo galaxy clusters. The core
of the Coma Cluster (Abell 1656) harbors two massive
ellipticals - NGC 4874 and NGC 4889 - supergiant
galaxies that have long dominated the cluster's evolution.
The view here is particularly striking in a large scope,
showing dozens of smaller systems surrounding these
central giants. To star-hop to the core region, locate 4thmagnitude Beta Coma Berenici then sweep 2° due west.
Perhaps the most famous supergiant elliptical galaxy
of all is M87, lying near the center of the Virgo Cluster.
One of the largest galaxies in the universe, it dwarfs
our Milky Way in every aspect. By the numbers, it's a
huge spheroid approximately 130,000 light-years across,
tipping the scales at 2.7 trillion Suns by some estimates,
with over 12,000 globular clusters in orbit. But its most
amazing feature is the relativistic jet of gas and dust
being ejected from the (at least) 3 billion-solar-mass
black hole at its core. First detected by Heber Curtis
of Lick Observatory in 1918, the ray was reportedly
observed visually by Otto Struve using the 100-inch at
Mount Wilson. A practiced observer - under excellent
conditions - can detect the jet with a 15-inch or larger
scope at high magniﬁcation. In a 24-inch scope at 457×,
it looks like a low contrast "spike" less than 20″ long
trending slightly north of west.
Interacting galaxies NGC 4782 and NGC 4783
comprise a very unusual giant elliptical system located
about 6° west of Spica, near the Corvus-Virgo border.
Together, they're the brightest member(s) of the very
rare class of co-rotating giant elliptical galaxies (similar
systems include NGC 545 and NGC 547, and NGC 750
and NGC 751). In the eyepiece of my 17-inch scope at
150×, the duo presents as a distinctly dumbbell-shaped
object, the galaxies' outer halos partially merged.
Much farther to the south is the closest and brightest
giant radio galaxy, NGC 5128, also called Centaurus A.
Discovered in 1826 by James Dunlop, it's the 5th-brightest galaxy in the sky. Just like M87, it harbors a gigantic
black hole at its core from which vast relativistic jets of
dust and gas are ejected. A trillion-solar-mass monster,
it's been devouring a smaller spiral galaxy over the past
several hundred million years. This is a tough target for
northern observers, but I've picked it up - just above
the horizon - with an 8-inch reﬂector from upstate New
York. Its unusual appearance is evident even in small
telescopes. In large instruments from low latitudes, the
view is stunning, showing a huge, intricate dust band
cutting diagonally across the bright oval disk.

GALACTIC OVERLORDS Though massive - the black hole at the
center of NGC 4889 is estimated to equal 21 billion solar masses, and
NGC 4874 holds more than 30,000 globular clusters in orbit - this pair
requires 10 inches of aperture or more in good seeing under dark skies.

Sk yandTelescope.com Januar y 2016

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Sky and Telescope - January 2016

Table of Contents for the Digital Edition of Sky and Telescope - January 2016