- Attachment: M51 Whirlpool Galaxy
- Our Sun is only one of 200,000,000,001 stars in the galaxy. And our Galaxy is only one of some 20 galaxies that are gravitationally connected in our Local Group of Galaxies. The Local Group occupies a sphere some 500,000 lightyears in diameter.
- The center of the galaxy is a bulge of a dense cluster of stars all of various ages. At the center of the bulge is a Blackhole that is 4,000,000 Solar Mass contained in a volume less that a few hundred AU’s across. An AU is an astronomical unit that is the distance from the Earth to the Sun. Our Solar System is some 100 AU across.
- The gas falling into the Blackhole emits 50 times more energy than hydrogen - helium fusion would. It is the in falling gas the we can see. It is the orbiting stars that we can use to calculate the mass of the Blackhole. We can not see the Blackhole itself it is only surmised from the gravitational data.
- The biggest thing we cannot see is the Dark Matter that surrounds our galaxy as a giant halo. Within this halo of Dark Matter is over 100 globular clusters of stars. These are old stars, 10 to 12 billion years old. They first formed very nearly the time of the Big Bang. Our galaxy is interacting with these Globular Clusters as well. Streams of stars are falling out of the Dark Matter and into our Milky Way Galaxy. Dwarf Galaxies are merging with the extended arms of our galaxy. When mergers occur a new crop of star formations occur inside the shockwaves.
- The Dark Matter Halo contains 80% of the mass of the entire galaxy. It is a complicated place with a lot of things happening. We can see streams of stars that mark the trails of mergers and interactions. New stars are forming amongst the old stars. Some stars are extremely metal-poor, meaning they do not contain the heavier elements above helium and lithium. This would indicate that they must be some of the first stars formed, a first or second generation in the earliest eras of star formation. In some of the stars the iron abundance is found to be less than 0.001% of the amount found in our Sun.
- Among the Local Group of galaxies ours is not an “ island universe”. Our galaxy is continuously interacting with other Dwarf Galaxies and streams of intergalactic gas. Some of the Dwarf Galaxies found are the most miniature of galaxies anywhere. In between all of this is an intergalactic medium that is full of Cosmic Rays. Cosmic Rays are charged particles that are hurled by the magnetic fields that also exist between the galaxies. The Cosmic Rays are charged nuclei, electrons, or protons, ions that are accelerated into a spiral path around the magnetic field lines.
- There are several more Reviews available that tell more about our home in the Cosmos. Request by number:
---------- #548 Our Milky Way
---------- #855 Calculations for the Milky Way’s Blackhole
--------- # 866 Learning about the Milky Way Part I
-------- # 867 Learning about the Milky Way Part II
--------- #938 Update on our Milky Way.
---------- #1058 Our Milky Way Galaxy
----------- #1124 What is inside out Milky Way Galaxy
----------- #1228 How many stars are in the Universe.
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707-536-3272, Wednesday, November 30, 2011
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