Chapter 14 Jane Lucas

Jane Lucas
Astronomy 100-Week 15 – Chapter 14
Observation of Jupiter
Yucatan Astronomers
The Milky Way Revealed
Galactic Recycling
The History of the Milky Way
The Mysterious Galactic Center

Observation of Jupiter – I observed the planet Jupiter with binoculars.  
Yucatan Astronomers – Arcadio Poveda and Luis Rodriguez Jorge were Yucatan Astronomers that were from different generations, but had the same greatness.  Luis Felipe has studied astronomical X-rays.  Arcadio Poveda has studied Ellipitcal Galaxies.  Both Poveda and Rodriguez are studying the Orion BN/KL objects together.  In particular, they discovered an explosion that happened 500 years ago.  Rodriguez discovered jet together with inflows of matter, and that mass is ejected through jets.
The Milky Way Revealed – The Milky Way galaxy appears in our sky as a faint band of light.  Gas and dust clouds obscure our view because they absorb visible light.  This is the interstellar medium (gas and dust) that makes new star systems.  If we could view the Milky Way from above the disk, we would see its spiral arms (ongoing star formation).  Stars in the disk all orbit in the same plane in the same direction with a little up-and-down motion.  Orbits of stars in the bulge and halo are elliptical, with random orientations. 
Galactic Recycling – Gas from dying stars mixes new elements into the interstellar medium, which slowly cools, making the molecular clouds where stars form.  Those starts will eventually return much of their matter to interstellar space.  Active star-forming regions contain molecular clouds, hot stars, and ionization nebulae.  Much of the star formation in our galaxy happens in the spiral arms.  
The History of the Milky Way – Halo stars are all old, with a smaller proportion of heavy elements than disk stars, indicating that the halo formed first.  Our galaxy formed from a huge cloud of gas, with the halo stars forming first and the disk stars forming later, after the gas settled into a spinning disk.  
What Lies in the Center of our Galaxy – Orbits of stars near the center of our galaxy indicate that it contains a black hole with 3 to 4 million times the mass of the Sun.
In conclusion we learned in Chapter 14 about the structure, motion, and history of our galaxy.  We also learned that galactic recycling that has made our existence possible.  We could not exist if stars were not organized into galaxies.  Also, the Milky Way acts as a giant recycling plant.