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