A little ramble through the winter sky - Perseus

Perseus was the hero of Greek mythology who rescued Andromeda who was chained to a rock waiting to be eaten by the Kraken sea monster.  Previously he had killed the medusa.  The Gorgons eye is marked by Algol. Perseus lies in a rich part of the milky way and is worth sweeping with binoculars.

In 1901 a brilliant nova appeared in Perseus it reached magnitude 0.2 between delta and beta.

Near gamma lies the radiant for the Perseid meteor shower which occurs every August.

Alpha  or Algenib which means side  or is sometimes known as Mirfak the elbow. It has a magnitude of 1.8 and is a F class supergiant with a surface temperature of 6,300 degrees and is 510 light years away.

Beta or Algol which means the winking demon is an eclipsing binary star that John Goodricke studied from York in 1782, he realised that there were two stars there eclipsing each other causing the star to change in brightness. The eclipse occurs every 2.8 days and the magnitude varies between 2.2 – 3.5. Goodricke did not discover the variability that was done by the Italian astronomer Montanari in 1669. Algol lies at a distance of 90 light years and has a surface temperature of 13,000’C and is a B class star. The star which is eclipsing Algol cannot be seen with the naked eye.

Zeta has a magnitude of 2.9 and is a B class supergiant with a temperature of 20,500’C and is 750 light years away.

Epsilon also has a magnitude of 2.9 and is a B0. Class star. As hot as zeta is epsilon is even hotter with an incredible temperature of 26,000’C and is 640 light years away. Both zeta and epsilon will probabably end their lives in a massive supernnva explosion.

Rho a semi regular variable varying between magnitude  3.3 and 4.0 in  aperiod or around 50 days. Its a M class red giant with a temperature of 3,800’C and is 308 light years away.

NGC 869 and NGC 884  Mag 3.7 the famous double cluster sometimes also known as chi perseus. These are open clusters with 350 and 300 stars respectively, lying about 7,600 ly away and about 300 light years apart.   NGC 869 and 884 are of magnitude 3.7 and 3.8 respectively, which in binoculars resolves into a grand pair of bright stellar star fields about 0.5 degrees apart. Each cluster contains over 300 blue white super giant stars. They are about 7,500 light years away.  

The letters NGC refer to the New General Catalogue of galaxies and star clusters and was introduced in 1888. Although its name is the New General Catalogue we still use that term today.  

In the 18th century the French astronomer Charles Messier was looking for comets with his small telescope. Although he found around a dozen comets none were very bright. Messier did however come across many fuzzy comet looking objects that  were not comets. He produced this list of noin comet objects whcih today is referred to as the Messier list of non comet objects and is used by astronomers. Its ironic that his comets are forgotten but his list of non comet objects has not been forgotten.                              

 While it was curious that Messier overlooked the double cluster maybe it was too obviously not a comet, he did however discover another open cluster in Perseus, this is M34 glimmering at mag 5.5 just visible to the naked eye to the right of Algol.

M34 is a loose aggregation of about 60 stars, M 34 is about 100 million years old, much older than the double cluster. M34 is only spread across about 10 light years. It is a wonderful sight in binoculars or small telescopes.

It was seen by Messier in 1764 who described it as a faint cluster of stars between the head of medusa and the left foot of Andromeda. The stars may be detected with a simple telescope.

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