Thank you

Thank you for reading this blog this year. It has been an interesting experiment.

As we head into spring/summer term, and all the students head out of town, it'll get a litte quiet around here. AST 305 will be undergoing some revision over the summer as well, so we'll have to see what happens to this blog. Hopefully, we'll see you in September.

In the meantime, have a wonderful summer.

Clear skies!

Last call for your input...

If you've been reading this, please take just a minute to fill out this very short evaluation. Really, it's very short!

W13 evaluation request

We have come to the end of another semester, so it is time once again to ask your help!

Please take a moment to evaluate this blog. We really will be using the evaluation results, not only to determine if our student blogger did a good job, but also to determine if we want to continue this project in the future. So please, really, take a moment to give us your feedback by April 12. I promise to read every word of it.

Thanks for reading,
S.A.M.

Stars

A star is a sphere of plasma that is held together by gravity. Stars come in many different shapes and sizes. The size of a star is totally dependent upon the size of the molecular cloud it formed from.

Most stars that astronomers have discovered are on the main sequence because stars spend 90 percent of their lives on the main sequence. A star on the main sequence fuses hydrogen into helium. The lower the mass of the star, the longer it stays a main sequence star. For example, our Sun is 4.5 billion years old and it is still on the main sequence. It will remain on the main sequence for about another 4 billion years. If a star is much more massive than our Sun it could spend as little as a million years as a main sequence star. 

After a star moves off of the main sequence it becomes a red giant. It swells an enormous amount and it becomes much cooler than it was when it was on the main sequence. A star like our Sun will stay on the main sequence for about a million years. At the end of a stars life, depending on its mass, it will become a white dwarf, a neutron star, or a black hole. A star like our Sun will become a white dwarf.

Star Formation

Star Formation

Stars go through many stages while forming. The stages can take anywhere between hundreds of thousands of years to millions of years. The amount of time that it takes to form a star depends on the mass of the star forming. Very massive stars will take less time to form while stars that are smaller will take more time to form.

Stars begin their lives in molecular clouds. Molecular clouds are often referred to as a star's nursery because they are were stars begin their lives. Molecular clouds are very dense clouds that are dense enough to allow the formation of molecules. The most common molecule found in molecular clouds is Hydrogen. Hydrogen is the most abundant element in the Universe. It makes up about 75% of all ordinary matter found in the universe.

Molecular clouds are so dense that turbulence and fluctuations within them cause certain amounts of matter to join together. After this matter joins together, the dust and gas in this portion of the cloud begins to collapse under its own gravity. While it collapses the matter near its center get hotter and hotter. This core is known as a protostar. A protostar is the stage before a star begins nuclear fusion. This matter is known as a star only when it begins nuclear fusion.

 Here is an image of a molecular cloud:

 

Green Pea Galaxy

A Green Pea galaxy is a galaxy that is undergoing high rates of star formation. Astronomers believe that they might be a type of Blue Compact Galaxy. They are named Green Pea galaxies because they appear very small in size and they look greenish.

These galaxies where discovered in 2007, by a couple of volunteer astronomers. They were discovered at redshifts between 0.112 and 0.360. The galaxies are very compact and emit a lot of lines from oxygen. The biggest these galaxies get is around 16,000 light years or 5,000 pc. So the Milky Way is about 6.25 times as big as a Green Pea galaxy. Here is an image of a Green Pea galaxy:

The Magellan telescopes

The Magellan telescopes are large custom built telescopes. They were built by the Carnegie Institution of Washington. They are located in Chile. The telescopes were built on the behave of the University of Michigan, the University of Arizona, the University of Harvard, and the Massachusetts Institute of Technology. Many people use these telescopes, including professors, Ph.D. Students, and postdoctoral astronomers. Each University shares the time equal on the telescopes.

The Magellan telescopes are very large. The main mirrors are f/1.25 paraboloids. Each of the mirrors are made of borosilicate glass and they weigh 21,000 pounds each. It took a really long time to build each mirror. It took 6 months to build the mold that the glass mirrors were made in. It then took 2 days to put the glass into the molds. After the glass was placed into the molds, it took 3 months for the glass to cool. Lastly, each of the mirrors had to be polished for several months. It also took a lot of time for the telescopes mount and track to be built. 

The Magellan telescopes staring operating in the early 2000s.