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M13

Messier 13
NGC 6205
Globular Star Cluster

Right Ascension 16h 41m 41s Best Seen 5/15-11/1
Declination 36° 27' 37" Magnitude 5.8
Constellation Hercules

Actual
Compared
to Sun
Distance ~25,100 ly --
Diameter > 150 ly --
Number of Stars ~1 million --
Actual Brightness -- 300,000
Age greater than 12 billion years ~2.5
Integrated Spectral Type F6 G2 V

What To Look For Through The Telescope


  1. Recommended eyepiece: 40mm or 80 mm.

  2. When people look through the telescope the cluster will appear similar to a pile of sugar or salt on a table.


M13 Information


  1. This cluster is about 30,000 light years from the center of the galaxy and it takes about 200 million years to complete one orbit. The sun takes about 250 million years to complete one orbit around the center.

  2. The cluster contains several hundred thousand stars -- Toward the center, stars are 500 times more concentrated than our solar neighborhood ... if the Earth was there, the sky would be filled with thousands of stars brighter than Venus or Sirius.

  3. Almost all the stars in the cluster are first generation stars–hence the cluster must be very old. It is estimated to be 12 billion years old, nearly as old as the Milky Way, and orbits outside the Milky Way disk.

  4. There is at least one young blue star in this cluster’s core called a “blue straggler” and is named Barnard No. 29

    a. Blue stragglers might be gravitationally captured by clusters.

    b. One blue straggler in another globular cluster (47 Tucanae) was gently formed by two orbiting stars which came together.

  5. This cluster is approaching us with a velocity of 150 miles per second.

  6. In 1974, one of the first radio messages addressed to possible extra-terrestrial intelligent species was sent to M13. The message was sent from the large radio telescope at Arecibo Observatory.

  7. First discovered by Edmond Halley in 1714, who noted that “it shows itself to the naked eye when the sky is serene and the Moon absent.” Charles Messier cataloged it in 1764. It is also reported in John Bevis’ Celestial Atlas. In 1787, Sir William Herschel pronounced it “a most beautiful cluster of stars, exceedingly compressed in the middle, and very rich.”

  8. In 1974, the Arecibo radio telescope transmitted a message to M13. This cluster was chosen because of its star density. But the message won’t reach M13 for 25,000 more years and when it arrives, M13 will no longer be where the message was aimed. This was more a technological demonstration than a serious attempt to contact alien life because the signal could only be received by an identical radio telescope.

  9. This cluster is visible in binoculars or a small telescope.

Home > Star Clusters > Globular > M13 > Reference top
References
Item Updated Notes
Coordinates 2002-08-14 just “tweaked” a bit
Distance 2002-08-14 http://messier.seds.org/m/m013.html
Actual Brightness
Number of Stars --
Diameter --
Age 2002-08-14 changed from >10 to >12
Integrated Spectral Type 2002-11-22 SIMBAD
Other 2002-08-14 http://messier.seds.org/m/m013.html
http://antwrp.gsfc.nasa.gov/apod/ap971104.html
https://apod.nasa.gov/apod/ap100527.html