Open Cluster: Messier 29
The small but fine open star cluster Messier 29 is located in the constellation "Cygnus", only 2° south of the 2.2mag bright star "Sadr". Its brightness is 6.6 magnitudes,
so the cluster can be seen as a faint diffuse patch of light even with smaller binoculars. The distance is given with about 5,500 light-years, but varies between 4,000 and
7,000 light-years depending on the source. From this a true diameter of about 10 light-years can be calculated. The cluster contains about 50 to 100 stars, but the exact number
is difficult to determine because of the many dust plumes in this region of the sky. Therefore the total mass of Messier 29 can only be estimated with 600 to 1,000 solar
masses.
The cluster itself is quite young with an age of 10 to 15 million years. The five brightest stars of the cluster are an evidence of this. They are giant white stars with a surface
temperature of 30,000 Kelvin and a luminosity of up to 160,000 suns. You can't imagine how it would be, if one of these stars would stand at the position of our sun... Even in
a distance of 200 lightyears the brightest stars of Messier 29 would still shine as bright as the planet Venus. By the way, the arrangement of the brightest stars has earned the
cluster the name "Little Pleiades".
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I pass this star cluster at least whenever I observe with a newer, bigger telescope. Because then I can determine the number of stars and I am happy when I can see more stars
than with the old telescope. By the way, with my new 20" f/3 it is 40-45 stars. Messier himself probably came up with 8 stars - but that was in 1764 with a much smaller telescope.
But I also like the shape: a charming little group of stars... For me the star cluster looks like the cooling tower of a nuclear power plant.
