The quadrilateral made up of ·, ‚, Èand ̇is not particular-
ly hard to identify.
The main interest in Cepheus is centred upon three
variables stars: ‰, Ìand VV. ‰is the prototype Cepheid,
and has given its name to the whole class; its behaviour
was explained in the 18th century by the young deaf-mute
astronomer John Goodricke. It forms a small triangle with
̇(3.55) and Â(4.19) which make good comparison stars,
though ‰never becomes as bright as ̇. The 7.5-magnitude
companion is an easy telescopic object, and seems to be
genuinely associated, since it and the variable share a
common motion in space.
ÌCephei is so red that William Herschel nicknamed it
the Garnet Star; although the light-level is too low for the
colour to be evident with the naked-eye, binoculars bring
it out beautifully. The range of ÌCephei is between mag-
nitudes 3.4 and 5.1, but the usual value is about 4.3, so
that the nearby Ó(at magnitude 4.29) makes a convenient
comparison. It has been suggested that Ìmay be of the
semi-regular type, but it is difficult to find any real
periodicity. The distance has been given as 1500 light-
years, in which case the luminosity is more than 50,000
times that of the Sun – making it much more powerful
than Betelgeux in Orion, which is of the same type. The
Garnet Star is so luminous that if it were as close as,
say, Pollux in Gemini, the apparent magnitude would be
7, and it would be conspicuous in the sky even in broad
daylight.
VV Cephei, close to Í(4.29), is a huge eclipsing
binary of the Zeta Aurigae type. The system consists of a
red supergiant together with a smaller hot blue companion;
the range is small – magnitude 4.7 to 5.4 – and the orbital
period is 7430 days, or 20.3 years. It is thought that the
diameter of the supergiant may be as much as 1600 times
that of the Sun, in which case it is one of the largest stars
known. The last eclipse occurred in 1996.
The two variables in the constellation are worth
mentioning. W, close to ‰, is a red semi-regular with a
long but uncertain period. Telescope users may care to
pick out the Mira variable S, which is one of the reddest of
all stars. There are no Messier objects in Cepheus.
Camelopardalis(alternatively known as Camelopardus).
This is a very barren far-northern constellation, and was
introduced to the sky by Hevelius in 1690. There is little
really of much interest here, but it is worth noting that
the three brightest stars, ·, ‚and 7, are all very remote
and luminous; 7 is well over 50,000 times as powerful
as the Sun.
Lacerta. Although Lacerta the Lizard, was one of the
original constellations listed by Ptolemy, it is very small
and obscure. There is a small ‘diamond’ of dim stars, of
which ·is the brightest; to find them, use ̇and ÂCephei
as guides. ÂCephei is just in the same binocular field with
‚Lacertae.
The only object of any note is the open cluster
NGC7243 (C16), which forms an equilateral triangle with
·and ‚and is just within binocular range. A bright nova
(CP) flared up in Lacerta in 1936, and reached
magnitude 1.9, but it faded quickly, and is now below the
15th magnitude.
BL Lacertae, which is too faint to be of interest to
the user of a small telescope, was once regarded as an
ordinary run-of-the-mill variable star, and was given the
appropriate designation, but when its spectrum was exam-
ined it was found to be something much more dramatic,
and is more akin to a quasar. It has given its name to the
whole class of such objects (see page 202), which are con-
ventionally known as ‘BL Lacs’.STAR MAP 3
BRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
27 Á 00 56 42 60 43 00 2.2v B0p
18 · 00 40 30 56 32 15 2.2v? K0 Shedir
11 ‚ 00 09 11 59 08 59 2.27 F2 Chaph
37 ‰ 02549 60 14 07 2.68 A5 Ruchbah
45 Â 01 54 24 63 40 13 3.38 B3 Segin
24 Ë 00 49 06 57 48 58 3.44 G0 Achird
Also above magnitude 4.3: ̇(3.67), È(3.98), Î(4.16); next comes ı(Marfak) (4.33). Úis an irregular variable which
can at times exceed magnitude 4.3, but is usually nearer 4.8.
VARIABLES
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
Ú 23 54.4 58 30 4.1–6.2? – F
Á 00 56.7 60 43 1.6–3.3 Irregular – Bp
· 00 40.5 56 22 2.1–2.5? Suspected – K
R2 3 58.4 51 24 4.7–13.5 Mira 431 M
SU 02 52.0 68 53 5.7–6.2 Cepheid 1.95 F
RZ 02 48.9 69 38 6.2–7.7 Algol 1.19 A
DOUBLES
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
Ë 00 49.1 57 49 315 12.6 3.4, 7.5 Binary, 480y
È 02 29.1 67 24 232 2.4 4.9, 6.9 Binary, 840y
CLUSTERS AND NEBULAE
MCNGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
52 10 7654 23 24.2 61 35 6.9 13 Open cluster
103 13 581 01 33.2 60 42 7.4 6 Open cluster
663 01 46.0 61 15 7.1 116 Open cluster
457 01 19.1 58 20 6.4 13 Open cluster
round ÊCasBRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
5 · 21 18 35 62 35 08 2.44 A7 Alderamin
35 Á 23 39 21 77 37 57 3.21 K1 Alrai
8 ‚ 21 28 39 70 33 39 3.23v B2 Alphirk
21 ̇ 22 10 51 58 12 05 3.35 K1
3 Ë 20 45 17 61 50 20 3.43 K0
Also above magnitude 4.3: È(3.52), Â(4.19), ı(4.22), Ó(4.29), Í(4.29).
The two famous variables can exceed magnitude 4 at maximum, ‰and Ì.
VARIABLES
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
‰ 22 29.2 58 25 3.5–4.4 Cepheid 5.37 F-G
Ì 21 43.5 58 47 3.4–5.1 Irregular – M
T2 1 09.5 68 29 5.2–11.3 Mira 388 M
VV 21 56.7 63 38 4.8–5.4 Eclipsing 7430 M+B
W2 2 36.5 58 26 7.0–9.2 Semi-regular Long K-M
S2 1 35.2 78 37 7.4–12.9 Mira 487 N
DOUBLES
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
Î 20 08.9 77 43 122 7.4 4.4, 8.4
‚ 21 28.7 70 34 249 13.3 3.2, 7.9
‰ 22 29.2 58 25 191 41.0 var, 7.5.
o 23 18.6 68 07 220 2.9 4.9, 7.1 Binary, 796y
Í 22 03.8 64 38 277 7.7 4.4, 6.5 Binary, 3800yThe brightest star is ‚; R.A. 05h 03m, 25s 1, dec. 60° 26’ 32”, mag. 4.03. The only other stars above mag. 4.3 are
7 (4.21) and ·(4.29).A small, obscure constellation. The brightest star is ·: R.A. 22h 31m 17s.3, dec. 50° 16’ 17”, mag. 3.77. The only
other star above mag. 4.3 is 2 (4.13).
CLUSTERS AND NEBULAE
M C NGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
16 7243 22 15.3 49 53 6.4 21 Open cluster;
about 40 starsCASSIOPEIACEPHEUSCAMELOPARDALISLACERTALacerta
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