99 Veil Nebula
When a massive star dies in a supernova explosion,
its gases are ejected in all directions into space.
Eventually, the gas may condense and combine with
interstellar hydrogen to create new stars. But long
before that happens, we can glimpse snapshots of
how such explosions change as they age by studying
objects at various phases of evolution.
Supernova 1987A in the Large Magellanic Cloud
is in the earliest years of such an explosion. In time,
a compact expanding region of stellar debris looks
something more like the Crab Nebula (M1; see #90).
And after a few thousand years of further expansion,
the gas becomes tenuous and you get a remnant
cloud like the Veil Nebula.
Between 1,410 and 2,100 light-years away (sources
disagree), the Veil Nebula and associated Cygnus
Loop form one of the closest supernova remnants to
the Sun. (Two in Vela and one in Orion are closer.) Its
gas has moved outward 65 light-years in every direc-
tion since its progenitor — a star about 20 times the
Sun’s mass — exploded about 10,000 years ago.
William Herschel, the father of deep-sky observ-
ing, discovered the Veil Nebula — or, at least, part
of it. He first noted NGC 6960, the segment behind
52 Cygni, now called the Western Veil. Since then,
astronomers have named and cataloged the other
scattered pieces that make up this single large rem-
nant. The Eastern Veil is NGC 6992 and NGC 6995,
with an extension designated IC 1340. In between the
main arcs in the nebula are three concentrations of
brightly glowing gas: Pickering’s Triangle (discovered
by astronomer Edward Charles Pickering’s assistant,
Williamina Fleming), NGC 6974, and NGC 6979.
Also called the Cirrus Nebula, the Veil is large
(about 3° wide) and bright enough to be seen with
binoculars under skies free from light pollution. It
looks wonderful in any optics, provided they have
either a field wide enough or an aperture large
enough to resolve the wispy filaments. An OIII filter
really brings out detail and is especially useful when
light pollution is an issue. — A.G.
64 ASTRONOMY • JANUARY 2022 ALISTAIR SYMON
98 M61
M61 was a problem for Charles Messier from the
start. He first encountered the spiral galaxy May 5,
1779, when he mistook it for a nearby comet whose
path he had been tracking. He repeated this error
the following night and then again on the 11th before
he finally noticed that the “comet” had not moved
against the stars.
Once Messier realized his mistake, he noted the
“nebula that happens to lie on [the comet’s] path
and at the same point in the sky,” probably confirm-
ing to him that these uncataloged objects were
but a nuisance to comet hunters. No matter; Italian
astronomer Barnabus Oriani had already discov-
ered M61 on the same night Messier first noticed it.
Oriani was also following the comet of 1779, but was
not fooled. Messier must have chuckled at Oriani’s
description of the object, as he called it “very pale,
looking exactly like the comet.”
Today we know M61 as a prominent member of
the Virgo Cluster of galaxies — despite its location
DAN CROWSONnearly 10° south of the cluster’s heart. We see thisnearly 100,000-light-year-long spiral wonder from
some 55 million light-years away, giving us a glimpse
of what our Milky Way would look like if seen face-on
at such a distance. Like the Milky Way, M61 sports a
small bar from which an intense inner spiral pseudo-
ring displays hefty bursts of star formation, hinting at
a lurking, central supermassive black hole.
M61 shines at a respectable magnitude 10 about
5° north and slightly east of Eta (η) Virginis. It lies
roughly halfway between the 6th-magnitude stars
16 and 17 Virginis. Be warned: About a dozen NGC
galaxies lie nearby, but M61 is the brightest. Its
intensely bright core is surrounded by a much fainter
disk that swells into view with 70–150x and averted
vision. Moderate-sized telescopes may trace out the
galaxy’s larger spiral structure. Images will reveal its
two main luminous arms — one of which bends into
two straight sections that meet at a sharp angle — as
well as a multitude of fainter arms branching off the
main arms. All these features are studded with star-
forming regions, several of which appear as mottled
patches. An especially large concentration appears
near the northern end of the bar. — S.J.O.