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M13

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

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What To Look For Through The Telescope

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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.

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M13 Information

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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. Almost all the stars in the cluster are first generation stars–hence the cluster must be very old.

3. There is at least one young blue star in this cluster’s core called a “blue straggler.”

   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.

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

5. 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.

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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