Galaxies


 * Let's start getting to even bigger structures than the solar system! To start I would like you to create a structural diagram of OUR galaxy. Show me what it looks like for the side and overhead views. Be sure to include the measurements, nuclear bulge, arms, dark matter. Once you have the basic features of the galaxy I want you to describe what HII regions, O-B Associations, and globular clusters are, as wellas, where they would be located in the galaxy.

PS I guess I should say that when I mean "measurements" I mean rotational speed, diameter, our location in it, etc.**

HII regions - a large cloud of gas and plasma of glowing low density in which star formation has recently taken place

O-B Associations - a gravitationally unbound group of stars, including a number of early spectral type (O- and B-stars) **//These are high energy stars. Very bright. O and B are a spectral class which places them in the upper left side of an H-R diagram.//**

Globular Clusters - spherical collection of stars that orbits a galactic core as a satellite. **//These also lie on the outer regions ofthe galactic plane which helped astronomers to define the shape of the galaxy we live in.//**

Rotational Speed = 254 km/s

Diameter of Our Galaxy = Estimated 100,000 Light Years. **//Is this typical for galaxies, or pretty common?//**

Number of Stars = 100 - 400 Billion. **//Again, is this pretty typical?//**

Thickness = 1,000 LY

Mass = 5.8 x 10​ 11 Solar Mass ( 1.988 9 2 × 1030 kg)

Nuclear Bulge - A tightly packed group of stars within a larger formation

Dark Matter - a conjectured form of matter that is undetectable by its emitted electromagnetic radiation, but whose presence can be found from gravitational effects on visible matter and background radiation.


 * //Do you know why these particular arms are called what they are?//**

I'm not sure, the only reason I can see is that you would get to the galaxy if you passed through the constellation its named after. Ex. if you wanted to travel to the Perseus arm, you would fly right "through" the Perseus constellation.

I will hopefully have added nuclear bulge and dark matter by Thursday.
 * //This is really nice work. Remember that dark matter within galaxies are far wider reaching than the visible stars.

Do you know what our nearest galactic neighbors are in the universe?//** The Andromeda galaxy.