STAR MAP 1
Canes Venatici, the Hunting Dogs – Asterion and Chara –
were added to the sky by Hevelius in 1690; they are held
by the herdsman Boötes – possibly to stop them from
chasing the Bears round the celestial pole. The only bright
star, ·^2 , was named Cor Caroli (Charles’ Heart) by the
second Astronomer Royal, Edmond Halley, in honour of
King Charles I of England. The star shows interesting
periodical changes in its spectrum, due probably to varia-
tions in its magnetic field. It is 65 light-years away, and
80 times as luminous as the Sun. Its companion, of magni-
tude 5.5, lies at a separation of over 19 seconds of arc, so
that this is a very easy pair.
The semi-regular variable Y Canum Venaticorum lies
about midway between Mizar and ‚Canum Venaticorum.
It is one of the reddest stars known, and has been named
La Superba; at maximum it is visible with the naked eye,
but binoculars are needed to bring out its vivid colour.
M51, the Whirlpool, lies near the border of Canes
Venatici, less than four degrees from Alkaid in the Great
Bear. It was discovered by Messier himself in 1773, and
is the perfect example of a face-on spiral; its distance is
around 37 million light-years. It was the first spiral to be
seen as such, by Lord Rosse in 1845.
Though a difficult binocular object, a modest telescope- say a 30-centimetre (12-inch) – is adequate to show its
form; it is linked with its companion, NGC5195. M94, not
far from Cor Caroli, is also a face-on spiral, and though it
is small it is not difficult to find, because its nucleus is
bright and distinct.
The other Messier spirals in Canes Venatici, M63 and
M106, are less striking. M63 is also a spiral, but the arms
are much less obvious. And M106 – added later to the
Messier catalogue – has one arm which is within range of
a 25-centimetre reflector.
M3 is one of the most splendid globular clusters in
the sky. It lies almost midway between Cor Caroli and
Arcturus, near the fainter star Beta Comae (magnitude 4.6)
and is easy to find with binoculars, while it can be
partly resolved into stars with a telescope of more than
8-centimetre aperture. Like all globular clusters, it is a
very long way away – over 48,000 light-years – and is par-
ticularly rich in RR Lyrae variables. The total mass has
been given as around 245,000 times that of the Sun. Not
surprisingly, it is a favourite target for amateur astro-
photographers. The integrated magnitude is about 6.4, so
that it is not very far below naked-eye visibility; Messier
discovered it in the year 1764.
Leo Minoris a small constellation with very dubious
claims to a separate identity; it was first shown by
Hevelius, on his maps of 1690. The system of allotting
Greek letters has gone badly wrong here, and the only star
so honoured is ‚, which is not even the brightest star in the
group. The leader is 46, which has been given a separate
name: Praecipua. It is in the same binocular field as Óand
ÍUrsae Majoris, and can be identified by its decidedly
orange colour. The only object of any interest is the
Mira-type variable R Leonis Minoris, which can reach
magnitude 6.3 at maximum, but sinks to below 13 when at
its faintest.
Hevelius had a habit of creating new constellations.
Some of these have survived; as well as Leo Minor, there
are Camelopardalis, Canes Venatici, Lacerta, Lynx,
Scutum, Monoceros, Sextans and Vulpecula, while others,
such as Triangulum Minor (the Little Triangle) and
Cerberus (Pluto’s three-headed dog), have now been
rejected. The constellation Leo Minor – which has no
mythological significance – was formerly included in Ursa
Major, and logically should probably have remained there.
BRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
77 Â 12 54 02 55 57 35 1.77 A0 Alioth
50 · 11 03 44 61 45 03 1.79 K0 Dubhe
85 Ë 13 47 32 49 18 48 1.86 B3 Alkaid
79 ̇ 13 23 56 54 55 31 2.09 A0 Mizar
48 ‚ 11 01 50 56 22 56 2.37 A1 Merak
64 Á 11 53 50 53 41 41 2.44 A0 Phad
52 „ 11 09 40 44 29 54 3.01 K1
34 Ì 10 22 20 41 29 58 3.05 M0 Tania Australis
9 È 08 59 12 48 02 29 3.14 A7 Talita
25 ı 09 32 51 51 40 38 3.17 F6
69 ‰ 12 15 25 57 01 57 3.31 A3 Megrez
1 Ô 08 30 16 60 43 05 3.36 G4 Muscida
33 Ï 10 17 06 42 54 52 3.45 A2 Tania Borealis
54 Ó 11 18 29 33 05 39 3.48 K3 Alula Borealis
Also above mag. 4.3: Î(A1 Kaprah) (3.60), h (3.67), ̄(Alkafzah) (3.71), Í(3.79), 10 (4.01).
VARIABLES
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
R1044.6 68 47 6.7–13.4 Mira 302 M
Z1156.5 57 52 6.8–9.1 Semi-reg. 196 M
DOUBLES
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
Ó 11 18.5 33 06 147 7.2 3.5, 9.9
̇ 13 23.9 54 56
AB 152 14.4 2.3, 4.0 Mizar/Alcor
AC 071 708.7 2.1, 4.0
CLUSTERS AND NEBULAE
M NGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
81 3031 09 55.6 69 04 6.9 25.7 14.1 Sb galaxy
82 3034 09 55.8 69 41 8.4 11.2 4.6 Peculiar galaxy
97 3587 11 14.8 55 01 12 194“ Planetary (Owl
Nebula)
101 5457 14 03.2 54 21 7.7 26.9 26.3 Sc galaxyBRIGHTEST STARS
No. Star R.A. Dec. Mag. Spectrum Proper name
hm s ° ‘ “
12 ·^2125602 38 19 06 2.90 A0p Cor Caroli
Also above mag. 4.3: ‚(Chara) (4.26).
VARIABLES
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
R1349.0 39 33 6.5–12.9 Mira 329 M
TU 12 54.9 47 12 5.6–6.6 Semi-reg. 50 M
Y 12 45.1 45 26 4.8–6.6 Semi-reg. 157 N
DOUBLE
Star R.A. Dec. P.A. Sep. Mags
hm °’ ° “
·^212 56.0 38 19 22.9 19.4 2.9, 5.5
CLUSTERS AND NEBULAE
M NGC R.A. Dec. Mag. Dimensions Type
hm °’ ’
3 5272 13 42.2 28 23 6.4 16.2 Globular cluster
51 5195 13 29.9 47 12 8.4 11.0 7.8 Sc galaxy
(Whirlpool)
63 5055 13 15.8 42 02 8.6 12.3 7.6 Sb galaxy
94 4736 12 50.9 41 07 8.2 11.0 9.1 Sb galaxy
106 4258 12 19.0 47 18 8.3 18.2 7.9 Sb galaxy
5195 13 30.0 47 16 9.6 5.4 4.3 Companion to
M51The brightest star is 46 (Præcipua), R.A. 10h 53m, dec. 34° 13’, mag. 3.83. Also above mag. 4.3: ‚(4.21).
VARIABLE
Star R.A. Dec. Range Type Period Spectrum
hm °’ (mags) (d)
R0945.6 34 31 6.3–13.2 Mira 372 MURSA MAJORCANES VENATICILEO MINOR The Whirlpool Galaxy,
M51, in Canes Venatici,
imaged by the NOAO Mosaic
CCD camera at the Kitt Peak
National Observatory. The
Whirlpool Galaxy consists of
NGC5194, a large spiral
galaxy, and a smaller
companion, NGC5195. The
red areas are nebulae within
the galaxy. M51 is about
31 million light-years away.Ga Atl of Univ Phil'03stp 2/4/03 7:36 pm Page 219