Sky & Telescope - January 2019 - 66

Observing in the Park

t COMPLEX NEBULA Situated in Camelopardalis, the Giraffe, the planetary nebula
NGC 1501 lies around 4,000 light-years
away. The bright central star that can be
seen in this image earned this object its
nickname, the Oyster Nebula. Remember,
you will not see this intricate nebula in all its
finest detail (and the colors here are arbitrary), but as you peek through your scope
on a cold winter's night, bear this image in
mind as you remind yourself that you are in
fact seeing the last gasps of a star across
the vast distances of space.

Pleaides (M45) or 600 million for the
late-middle-aged Beehive (M44).

A Dip into Perseus
If you proceed from Delta Cas to
Epsilon and then double back to
form an imaginary ﬁfth leg to Cassiopeia's W, you land atop the huge,
loose open cluster Stock 2, which
straddles the Cassiopeia-Perseus
border. Measuring roughly 1° across
and dominated by two dozen 8thand 9th-magnitude stars, it's best
observed at the lowest magniﬁcation
that your telescope can achieve. The
cluster's apparent size indicates that
it must be nearby, and indeed it lies just 1,000 light-years away.
At an estimated age of 170 million years, Stock 2 is also by
far the oldest cluster in our tour. You might guess that by the
fact that so many of its stars are almost identical in brightness. In older clusters, all the brightest, most massive stars
have already burned out.
Many people see Stock 2's stars as the ﬁgure of a giant.
One hand grasps a chain of 6th- and 7th-magnitude stars
that stretches 2° south to the peerless Double Cluster.
The apparent proximity of Stock 2 to the Double Cluster
is an illusion. Stock 2 lies in our galaxy's Orion-Cygnus Arm
(also called the Local Arm and many other names), the same

arm that hosts our own solar system.
All the other clusters we've discussed
so far are much farther away, in
a particularly active star-forming
region of the neighboring Perseus Arm. The superposition of
nearby Orion-Arm clusters with luminous young Perseus-Arm
clusters is what makes this region so rewarding to explore.
I never tire of viewing the Double Cluster through any
instrument at any magniﬁcation under any conditions. Its
components are among the most luminous open clusters
known; each appears as bright as the Beehive Cluster despite
being 14 times more distant. If the Double Cluster were at
the same distance as the Beehive, it would appear as bright
as Jupiter and bigger than Cassiopeia's W. For more information on this amazing cluster pair, see Sue French's discussion on page 54.

Jewels of the Wintry North
WZ Cassiopeiae
Eta Cassiopeiae

Type
Carbon star
Double star

Mag(v)
6.9-8.5
3.4, 7.5

Size/Sep

Dec.

01.3 m

+60° 21′

13″

49.1m

+57° 49′

19.5 m

+58° 17′

NGC 457

Open cluster

6.4

13′

M103

Open cluster

7.4

6′

1h 33.4m

+60° 39′

NGC 663

Open cluster

7.1

15′

1h 46.3m

+61° 13′

6′

44.4m

+60° 40′

44.0 m

+61° 53′

NGC 659

Open cluster

7.9

NGC 654

Open cluster

6.5

6′

Stock 2

Open cluster

4.4

60′

2h 15.6 m

+59° 32′

Double Cluster

Cluster pair

2.9

45′ × 30′

2h 20.7m

+57° 08′

14′

16.3m

+60° 02′

41.8 m

+62° 39′

3h 57.4m

+63° 04′

7′

07.8m

+62° 20′

05.9 m

+61° 48′

52″

07.0 m

+60° 55′

Stock 23

Open cluster

5.6

U Camelopardalis

Carbon star

7.0-8.0

Kemble's Cascade

Asterism

150′

NGC 1502
UV Camelopardalis
NGC 1501

Open cluster
Carbon star
Planetary nebula

5.7
7.5-8.5
11.5

Angular sizes and separations are from recent catalogs. Visually, an object's size is often smaller than the cataloged value and varies according to the aperture
and magnification of the viewing instrument. Right ascension and declination are for equinox 2000.0.

JA N UA RY 2 019 * SK Y & TELESCOPE

ESA / HUBBLE / N ASA / M A RC CA N A LE

Object

Sky & Telescope - January 2019

Table of Contents for the Digital Edition of Sky & Telescope - January 2019