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AUGUST 2008 VIEWING LIST
Object
Type
14” Scopes
M13
M57*
M8 (Lagoon)*
M20 (Trifid)*
M17*
M22
M27*
M15
NGC7331**
GC
PN
EN
EN
EN
GC
PN
GC
Gal
4” Refractor
Mizar & Alcor
95 Herculis
Epsilon Lyrae
Albireo
S Cephei
MS
MS
MS
MS
Carbon Star
Size
16’
1’
90’
28’
40’
17’
8’
12’
11’
-
Distance
25,100 LY
2,300 LY
5,200 LY
5,200 LY
4,890 LY
10,400 LY
1,250 LY
33,600 LY
46,000,000 LY
81-78 LY
470 LY
160 LY
380 LY
1353 LY
Coordinates
16h 42’
18h 53
18h 04’
18h 03’
18h 21’
18h 36’
19h 59
21h 30’
22h 37’
+36 28’
+33 02’
-24 23’
-23 02’
-16 11’
-23 54’
+22 43’
+12 10’
+34 25’
13h 28’
18h 02’
18h 44’
19h 30’
21h 35’
+54 55’
+21 36’
+39 40’
+27 58’
+78 37’
Abbreviations:
MS = Multiple Star, EN = Emission Nebula, RN = Reflection Nebula, Gal = Galaxy, GC = Globular
Cluster, LY = Light Year, OC = Open cluster, PN = Planetary Nebula, SR = Supernova Remnant,
CS = Carbon Star, * = Video imaging optional, ** = Video imaging recommended. 1 Astronomical Unit =
93,000,000 miles.
OBJECT DESCRIPTIONS – AUGUST 2008
M13 At a distance of 25,100 light years, this globular cluster in the constellation Hercules (HER-cueleez) is about 145 light years in diameter. The age of M13 has been estimated at over 10 billion years. It
contains over 300,000 stars. At the center, stars are about 500 times more concentrated than in our
solar neighborhood. To a being living near the center of M13 there would be no night sky as we know it.
Due to its age, however, life as we know it would be highly unlikely because the elements necessary for
life are not present. There is some current speculation that M13 is actually the ancient core of a small
galaxy cannibalized by the Milky Way billions of years in the past.
M57 The Ring Nebula is an atypical planetary nebula in the constellation Lyra (LIE-ruh). Whereas for
many years it was assumed that the parent star ejected a spherical shell of gas that we see as a ring,
recent research indicates that we are actually seeing an expanding torus, or donut, of gas illuminated by
an earth-size white dwarf star, and viewed from above. (Use an Olll filter for eyepiece viewing)
M8 The Lagoon Nebula in the constellation Sagittarius (Sah-jih-TAIR-ee-us) is an emission nebula about
140 x 60 light years in size. As the hydrogen gas that makes up the nebula absorbs ultraviolet radiation
from nearby young stars, it re-radiates, or emits, photons in the red light of hydrogen. Our eyes are not
normally sensitive enough to detect the red color in small telescopes.
M20 The Trifid Nebula in the constellation Sagittarius (Sah-jih-TAIR-ee-us) is famous for its
characteristic visual three-lobed appearance. Dark gas and dust clouds in the foreground block light to
produce the tri-lobed character of this emission nebula. However, the video clearly shows four distinct
components. Look for an adjacent faint reflection nebula component.
M17 is a bright emission nebula centered on an open star cluster in the constellation Sagittarius (Sahjih-TAIR-ee-us). After the famed nebula in Orion, M17, known also as the Omega, Horseshoe, or the
Swan, is the brightest emission nebula in the northern hemisphere. The total gas cloud contains an
estimated 800 solar masses. Look carefully either through an eyepiece or with the video camera and
decide which name is most fitting.
M22 is a globular cluster in the constellation Sagittarius (Sah-jih-TAIR-ee-us). At a distance of 10,400
light years, M22 is one of the nearest globulars in the northern sky. Brighter than famous M13, it glows
at 5th magnitude. The diameter of the object is about 97 light years. Seen through a curtain of foreground
stars in the Milky Way, M22 is an extraordinary sight, and, in my opinion, superior to M13 in Hercules.
M27 The Dumbbell Nebula in the constellation Vulpecula (vul-PECK-u-la) was the first planetary nebula
discovered. Through the visual scopes, the brightest sections resemble an hourglass. The video camera
reveals the outer gaseous regions that complete the spherical structure of the ejected gas bubble. The
age is uncertain, with estimates ranging from 3,000 to 48,000 years. (Use an Olll filter for optimum
eyepiece viewing)
M15 in the constellation Pegasus (PEG-uh-sus) is among the more conspicuous of the globular clusters.
At a distance of about 33,600 light years, it has a diameter of about 175 light years. Having experienced
a process called Core Collapse, M15 has what may be the densest core of any known globular cluster,
with hints of a supermassive object at its center. M15 is approaching us at 107 km/sec.
NGC7331 Discovered by William Herschel in 1784 in the constellation Pegasus (PEG-uh-sus), this is a
bright type Sb spiral galaxy viewed at a small inclination from edge-on. Look for evidence of spiral
structure & the faint presence of neighboring galaxies in the field of view.
Mizar & Alcor This pair in the constellation Ursa Major (URR-suh, MAY-jer) is a visual double.
However, Mizar takes its place in the celestial hall of fame as the first known Binary Star, one that
consists of a pair of gravitationally bound stars that orbit each other. Found to be double in 1650, the
pair is about 500 astronomical units apart & takes at least 5000 years to orbit about each other. More
remarkably, each of these two components is AGAIN a spectroscopic double star.
95 Herculis in the constellation Hercules (HER-cue-leez) is a binary with a visual separation of 6.3
seconds of arc. The two stars orbit 900 astronomical units apart. The orbital period is approximately
11,000 years. Note the interesting colors.
Epsilon Lyrae, popularly known as the Double-Double, is a multiple star system in the constellation
Lyra (LIE-ruh). Appearing as a double star at low magnification, as power and resolution increase each
star splits into a close binary. While some observers see color differences, most see the stars as two
pairs of white headlights oriented nearly perpendicular to each other.
Albireo Beta Cygni, in the constellation Cygnus (SIG-nus) is probably not a true binary, but a visual
double star with extraordinary color contrast. If it is a binary it would have an orbital period of about
75,000 years. The yellow star is actually a spectroscopic binary in its own right. The yellow primary
shines at 950 times our sun’s brightness and 50 times its mass, while the binary’s invisible secondary
star is 100 times more luminous than our sun with 3.2 times it’s mass. The striking blue star shines at
190 times the luminosity of our sun with 3.3 times its mass.
S Cephei in the constellation Cepheus (CEE-fee-us) is a Carbon Star, a red giant with a large amount
of carbon dust floating in it’s upper atmosphere. The dust passes red light, making carbon stars the
reddest stars to be seen through a telescope. At magnitude 7.5, it is a beautiful deep red and, at its high
declination may be glimpsed all year long.
F. Lockhart