stellar sapphire Vega sparkles high
in the west this month. Famous as the
fifth brightest star in the entire night sky, Vega is so dazzling that
punches through even the most severe light pollution. You simply
can't miss it!
Above: Autumn star map from
by Phil Harrington.
Finder chart for this month's Binocular Universe.
adapted from Touring the Universe
Binoculars Atlas (TUBA)
you get, take a look at Vega through your binoculars. As you are
enjoying its blue-white luster, consider
that the light you are seeing is only 25 years old. Twenty-five
years works out to be 147 trillion miles. That’s just a
town or two away on the cosmic distance
scale. We're practically neighbors.
of Lyra symbolizes the lyre, or harp, owned by the mythological
Orpheus. Vega marks a portion of the
harp's handle, while four fainter stars in a parallelogram frame its
body. Light pollution may hide those four
if you can't make them out by eye, try using your binoculars
instead. Each is well worth a closer look.
instance, there is
more to 3rd-magnitude Sheliak
(Beta [ß] Lyrae),
at the parallelogram's southwestern corner, than just a faint
star. Sheliak is actually an eclipsing binary that
is perfect for binocular study. Over the
course of just under 13 days, an unseen companion star causes Sheliak
from magnitude 3.3 to 4.3. Use the chart
here to monitor the changes in appearance. By comparing Sheliak's
brightness to that of nearby stars that
vary, can you confirm its 13-day cycle?
photographed planetary nebula of all, M57,
the Ring Nebula, lies along the southern edge of the harp's
parallelogram. To spot it, look midway
between Sheliak and Sulafat (Gamma [?]
for three very faint stars that create a tiny right
triangle. The star at the right angle is
actually the Ring. Although it takes at
least 50x to make out the classic smoke-ring shape, I've seen M57 as a
star-like point through binoculars as small as 7x35s. Give this
challenge a try tonight and let me
know if you are successful. I would be
interested in finding out just how small a pair of binoculars will uncover
scan southeast of Sulafat, toward the star Albireo in Cygnus, and pause
about halfway in between. There, you'll
find a conspicuous asterism of stars shaped like a number 7. If
you look just to the 7's southeast, you
should also spot a faint smudge that doesn't quite look like a
star. That's the globular cluster M56.
Although 100,000 stars make up M56, the
cluster is much too far away to be resolved through binoculars.
That task requires at least a 6-inch
smallest pocket binoculars, however, will reveal Delta (d)
Lyrae, at the parallelogram's
northeastern corner, as two close-set stars.
In fact, some sharp-eyed stargazers don't
need any optical aid at all to see them. The brighter star in the
pair, 4.3-magnitude Delta-2, looks
while 5.6-magnitude Delta-1 is bluish-white.
stars belong to a scattered open cluster nicknamed, appropriately, the
cataloged as Stephenson 1. Fifteen
stars belong to Stephenson 1, though most are too faint for
Although both Deltas are members of the cluster, they are not a true
system. Studies suggest that Delta-1 lies about 1,200 light years away,
Delta-2 is about 200 light years closer to us.
cluster Stephenson 1 as portrayed
through the author’s 16x70 binoculars.
our tour is Epsilon (e) Lyrae.
it just to the northeast of Vega. If you
have sharp vision, you may also be able to split Epsilon into two stars
alone. The stars are separated by 3.5
arc-minutes, which is near the naked eye's resolution limit. Of course, with binoculars, Epsilon is easy to
resolve into two points of light. The
northernmost of the pair is labeled Epsilon-1, while the southern
also known as the Double-Double, as Epsilon-1 and Epsilon-2 are each
pairs of stars. Unfortunately, it takes at
least 80x to see all four Epsilon affiliates. Even though we can see only two stars in binoculars, the added
to the southwest and Zeta Lyrae to
the southeast create a very pretty binocular scene.
wait, there's more!
Zeta (?) Lyrae is
actually a challenging double star for binocular viewing. Zeta is composed of 4th- and 6th-magnitude
suns separated by about 44 arc-seconds. The fainter companion lies due south of the brighter star.
I can just make out both through my 10x50
binoculars, while the added oomph of my 16x70s cleaning
resolves them. Both impress me as
shining pure white. How about you?
we discussed how Sheliak
fun variable star to monitor through binoculars. If you are a
devout variable-star fan, then you may already know about R Lyrae.
R is a type-M red semi-regular star that fluctuates between
5.0 over the course of 50 days. Look for
it in the northern part of the constellation, about 6°
have RR Lyrae tucked
just inside Lyra's
northern border. With great precision,
this star rises to magnitude 7.1, falls to magnitude 8.1, and then
back up again in just 13 hours, 36 minutes. RR Lyrae heads up a class of variable stars that are also known
"cluster variables," since many are found within globular
clusters. RR Lyrae stars are well known
for their period-luminosity relationship. By studying the
variations of RR Lyrae stars versus their periods of variability,
can calculate the stars' true luminosities. By knowing both the luminosity and apparent magnitude, the
the star can be
are shown on the finder chart above, along with several suitable comparison
can be used to judge each variable's magnitude value. The visual magnitude of each comparison star
is shown in italicized
green type, with
the decimal point omitted to avoid confusing it for a faint star. For instance, the number 43
next to Zeta Lyrae at the parallelogram's northwestern corner indicates
shines at a constant visual magnitude 4.3.
will join the crew of the Starship Enterprise for more deep-sky
adventures. Till then, remember my mantra:
Two eyes are
better than one.
About the Author:
Harrington has written 9 books on astronomy, including Star Ware,
Watch, and his latest, Cosmic Challenge. Visit his web site, www.philharrington.net,
copyright 2012 by Philip S. Harrington. All
rights reserved. No
reproduction, in whole or in part, beyond single copies for use by an
individual, is permitted without written permission of the copyright