41 lines
1.3 KiB
Org Mode
41 lines
1.3 KiB
Org Mode
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:PROPERTIES:
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:ID: e5dc49a0-af4f-4546-b1d0-624fd54435ad
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:END:
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#+title: M13 Globular Cluster
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#+filetags: :celestial_objects:
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#+STARTUP: latexpreview
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Messier 13 is one of the best-known globular clusters in the night sky.
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Messier number: 13
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New General Catalogue (NGC) number: 6205
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Constellation: Hercules
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Distance from Earth: 25,100 ly
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Discovered by: Edmond Halley in 1714
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* Physical Characteristics
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- M13 contains several hundred thousand stars.
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- The stars are metal-poor and densely packed in the center.
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- Stars have low-,etallicity, which means they wre likely formed in environments which fewer heavy metals.
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* Notable Features
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- M13 has a diameter of about 145 ly.
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- M13 contains many blue-stragglers, which are stars that appear hotter and younger than all the other stars.
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- Contains many variable stars, especially RR Lyrae variables, useful for determining distance and properties of globular clusters.
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- There is onginog research into whether or not M13 contains a central medium-sized black hole.
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* Observation and Viewing
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- Viewed best in Summer and early Fall.
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- Seen in the nothern hemisphere
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- Spans 22 arcminutes of the sky. For comparison, the Moon only spans 30 arcseconds of sky.
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- Diameter of 145 ly calculated using distance, angular size, and simplifying using the small-angle approximation.
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