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Constellation
Report |
| Our Constellation report is an easy way for people to
become familiar with the nighttime sky. We’ll discuss myths associated
with the various constellations as well as describing the numerous deep
sky objects residing in the area. No equipment is required to view the
constellations, though a star chart can be quite helpful. This ease of
observing makes constellations a natural place to begin your journey to
the stars.
This weekend we move on to the constellation
Aquarius
- The Water Bearer. Aquarius is located west of Pisces and
below the neck of Pegasus. Aquarius is typically depicted as a man pouring
water from a water jar.
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Deep
Sky Report
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| We begin our journey through Aquarius with a visit to Alpha Aquarii(mag2.93). This star has a similar spectrum to our sun. However, it is much larger than our sun. Estimates put it's size at over 80 times the diameter and it's total luminosity at over 6000 times that of our sun.
Next up is Beta Aquarii(mag 2.86). This star has almost the same total luminosity as Alpha Aquarii, but is located at a slightly smaller distance and hence is slightly brighter. Why is the beta star brighter than the alpha star you may be wondering. Good question. This probably has to do with the fact that less accurate methods were used to determine visual magnitudes when the stars were first cataloged. This may have resulted from Beta's more southerly declination. The Alpha star, being higher in the sky, may have appeared brighter. Modern instruments and techniques have remedied this. |
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 Let's start things off with a nice, big Globular Cluster -- M2(mag6.5). This is a really cool globular. It's big and bright and at least in the big scope, resolves
right down to the core. Discovered by Jean-Dominique Maraldi in 1746, M2 is located some 37,000 light years away and has a diameter of about 150 light-years. M2 is believed to contain about 150,000 stars, and is one of the richer and more compact globular clusters. It has a class II designation. This refers to a classification scheme running from class I (extremely rich and highly compressed) to class XII (very loose and sparsely clustered). This cluster is slightly elliptical , as can be seen in the accompanying. Its brightest stars are red and yellow giants of magnitude 13.1 -- these, of course, are not visible in this black and white image :(
With its visual magnitude of 6.5 mag, M2 is a difficult object for naked-eye observing , but an easy target for binoculars or the smallest of telescopes. A 4" telescope will be unable to resolve this cluster to it's core. At best, it'll show some of the brightest member stars spread over the mottled nebulous background image caused by the unresolved stars. With an 8", the cluster is partly resolved into stars, well into the center under good viewing conditions. Larger scopes, 10-inch up, fully resolve this cluster. A peculiar dark lane crosses the north-east edge of the cluster, suggestions of which are visible in our image; larger telescopes (16-inch up) show several other, less prominent darker features or regions.
M2 is found rather easily from Alpha and Beta Aquarii, as well as Epsilon Pegasi. It is 5 degrees north of Beta Aquarii, on the same declination as Alpha Aquarii.
This amazing shot was taken by Utah Skies Astrophotographer of the
Month, Al Kelly.
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 Next up is another Globular Cluster M72(mag9.3) This one is no where near as impressive as it's neighbor to the north. It is beautiful, but in a much more subtle manner. Discovered 1780 by Messier's assistant Pierre Mechain, M72 is one of the more remote of Messier's globular clusters: At an estimated 53,000 light years, it lies a considerable distance beyond the Galactic Center. An interesting fact about M72 is that it is one of the most intrinsically luminous globular clusters. Were it located closer, it would undoubtedly be a deep sky favorite. Its diameter is approximately 90 light years.
The brightest stars in M72 are about mag 14 so, you'll need at least 10" of aperture to begin to resolve the individual stars.
To find M72, follow a line from alpha through beta and continue for the same distance as their separation.
This beautiful shot was taken by Jay Potts. Checkout
more of Jay's very impressive work. |
 Next
up is NGC7293(mag ). Also known as the Helix Nebula.
This awesome image was created by Robert
Gendler. |
 Continuing on our journey, we come to a very interesting object, NGC7009, the Saturn Nebula(mag8). This object looks like a pale blue star at low power.
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| We'll finish our journey through Aquarius with this weeks double Utah Skies Challenge Objects. Spiral Galaxy NGC 7723(mag11.1) and Barred Spiral Galaxy NGC 7727(mag10.7). We list these objects together due to their close visual proximity. NGC7727 is only about 40' (2/3° ) north of NGC7723. If you find one, you'll most likely find the other -- possibly even at the same instant. Checkout the star chart above. You'll see both objects in the southeastern portion of Aquarius. NGC7723 is not quite as bright as NGC7727. But, it's also not quite as big. So, the light is a bit more concentrated.
Good Luck! |
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Did you ever consider... |
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"The exploration and ultimate colonization of the solar system is the only future worthy of truly great nations at this time in history. The Soviets, who cannot even feed themselves, seem to understand this." - John S. Powers |
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