Our Neighbouring Galaxy

Most constellations are home a spectacular deep-sky object. Hercules has M13 a great globular cluster. Lyra has the Ring Nebula the ghostly remains of a star and Perseus has the Double Cluster two open clusters of stars that can be seen naked. Andromeda is no exception with a slightly different twist. In almost all cases, the celestial wonders are located in our galaxy. Whereas M31 also known as the great Andromeda Galaxy is the closest galaxy to us and is located some 2.9 million light-years from us. From a cosmic perspective, that is close.

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The Andromeda Galaxy is estimated to be 250,000 light-years in length which is 2.5 times ours and harbours two smaller satellite galaxies catalogued as M32 and M110. The most striking feature is seeing M31 without optical aid under dark sky conditions. Visually, we see the concentrated area towards the nucleus but photography registers the fainter parts of the starry disk. Its overall length is three degrees or six full moons placed side by side.

Photo of M31

The galaxy is also home to numerous globular clusters to which a few are observed visually with photography needed to locate the fainter ones. With a telescope and a wide-angle eyepiece, one or two dust lanes are quite evident along with NGC 206 – a bright “star cloud” located at the galaxy’s edge near M32. From M31 move down the chain of three stars to the bright star Mirach. Here is a magnitude 2.07 spectral class M0 star residing 200 light-years from Earth. From here, try to put the star just outside the field of view to spot NGC 404 also called Leo 1. In fact, this isolated dwarf lenticular galaxy is found only seven arc minutes from Mirach. The galaxy itself is some ten million ly away and glows at magnitude 11.2.

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Author: 
garyboyle@xplornet.ca
eNews date: 
Thursday, September 1, 2016
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