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M3 Globular Cluster |
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Globular Cluster M3
(NGC 5272), class VI, in
Canes Venatici.
M3 is one of the most outstanding globular clusters, containing an
estimated half million stars. At a distance of about 33,900 light years, it
is further away than the center of our Galaxy, the Milky Way, but still
shines at magnitude 6.2, as its absolute magnitude is about -8.93,
corresponding to a luminosity of about 300,000 times that of our sun. M3 is
thus visible to the naked eye under very good conditions - and a superb
object with the slightest optical aid. Its apparent diameter of 18.0 arc
minutes corresponds to a linear extension of about 180 light years; Kenneth
Glyn Jones mentions an estimate of even 20 arc minutes from deep
photographic plates, corresponding to about 200 light years linear diameter.
It appears somewhat smaller in amateur instruments, perhaps about 10 minutes
of arc. But its tidal radius, beyond which member stars would be torn away
by the tidal gravitational force of the Milky Way Galaxy, is even larger:
About 38.19 minutes of arc. Thus, this cluster gravitationally dominates a
shperical volume 760 light years in diameter. Additional
Info Messier
Index - M3 |
Camera = Meade
DSI
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M4 -
Globular cluster |
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Globular Cluster M4
(NGC 6121), class IX, in
Scorpius. M4 would be
one of the most splendid globulars in the sky if it were not obscured by
heavy clouds of dark interstellar matter. Interstellar absorption also
reddens the color of the light from the cluster, and gives it a slightly
orange or brown-ish appearance on color images. Its angular diameter, seen
on deep photographs, is about 36 minutes of arc, more than that of the Full
Moon; this corresponds to a linear diameter of about 75 light years. On
typical photos it appears somewhat smaller at about 26', and visually it was
estiamted at 14 arc minutes. Its tidal radius, determined by the distance
where tidal gravitational forces of the Milky Way Galaxy would cause member
stars to escape, is estimated at 32.49', or about 70 light-years, so that
this globular gravitationally dominates a spherical volume 140 light-years
in diameter. Additional Info
Messier Index - M4 |
Camera = Meade
DSI
Exposure = 15Sec X 30 Frames
Processed =
Photoshop 6
Conditions = Fair - Near full
Moon |
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M13 -
Great Hercules Globular Cluster |
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Globular Cluster M13
(NGC 6205), class V, in
Hercules.
M13, also called the `Great globular cluster in Hercules', is one of the
most prominent and best known globulars of the Northern celestial
hemisphere. It was discovered by
Edmond Halley
in 1714, who noted that `it shows itself to the naked eye when the sky is
serene and the Moon absent.' According to
Charles
Messier, who
cataloged
it on June 1, 1764, it is also reported in
John Bevis'
"English" Celestial Atlas. At its distance of 25,100 light years, its
angular diameter of 20' corresponds to a linear 145 light years - visually,
it is perhaps 13' large. It contains several 100,000 stars; Timothy Ferris
in his book Galaxies even says "more than a million". Towards its
center, stars are about 500 times more concentrated than in the solar
neighborhood. The age of M13 has been determined by Sandage as 24 billion
years and by Arp as 17 billion years around 1960; Arp later (in 1962)
revised his value to 14 billion years (taken from Kenneth Glyn Jones). Additional Info
Messier Index -
M13 |
Camera = Meade
DSI
Exposure = 25X15 Sec
Processed =
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M45
- Open Cluster
Full size picture |
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Open
Cluster M45 , type 'c', in
Taurus The
Pleiades. Known pre-historically. Mentioned by Homer about 750
B.C. and Hesiod about 700 B.C. The Pleiades are among those objects which
are known since the earliest times. At least 6 member stars are visible to
the naked eye, while under moderate conditions this number increases to 9,
and under clear dark skies jumps up to more than a dozen (Vehrenberg, in his
Atlas of Deep Sky Splendors, mentions that in 1579, well before the
invention of the telescope, astronomer Moestlin has correctly drawn 11
Pleiades stars, while Kepler quotes observations of up to 14). Modern
observing methods have revealed that at least about 500 mostly faint stars
belong to the Pleiades star cluster, spread over a 2 degree (four times the
diameter of the Moon) field. Their density is pretty low, compared to other
open clusters. This is one reason why the life expectation of the Pleiades
cluster is also pretty low
Additional Info
Messier Index - M45 |
Camera = Cannon 300D
Exposure = 30 Mins X 2
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M53 -
Globular Cluster |
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Globular Cluster M53
(NGC 5024), class V, in
Coma Berenices.
Globular star cluster M53 is one of the more outlying globulars, being about
60,000 light years away from the Galactic center, and almost the same
distance (about 58,000 light years) from out Solar system. At this distance,
its apparent angular diameter of 13' corresponds to a linear diameter of
roughly 220 light years. It is rapidly approaching us at a velocity given by
Mallas as 112 km/s, by Harris as 79 km/s. M53 has a bright compact central
nucleus of about 2' in diameter, although its stars are not very
concentrated toward the center when compared to other globulars, and a
gradually decreasing density profile to the outer edges.
Harlow Shapley
classified it in density, or concentration class V. While the NGC, following
John Herschel,
suspected its brightest red giant stars at about 12th magnitude, the Deep
Sky Field Guide lists them at 13.8 mag, and the hirizontal branch at about
magnitude 16.9. The cluster's overall spectral type is givan as F6.
Additional Info Messier
Index - M53
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Camera = Meade
DSI
Exposure = 60X15 Sec
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M79 Globular Cluster
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Globular Cluster M79
(NGC 1904), class V, in
Lepus. M79 (NGC 1904),
class V, in Lepus M79
is a beautiful globular cluster at a quite unusual location in the sky: Most
globulars are grouped around the Galactic center, but this is one of the few
which are situated in the other hemisphere. It is little over 40,000 light
years from us, but about 60,000 light years from the galactic center.
Additional Info
Messier Index - M79 |
Camera = Meade
DSI
Exposure = 15X15 Sec
Processed =
Photoshop 6 |
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