Jason Shilling Kendall

Introductory Astronomy Videos

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Module 7: Measuring the Properties of the Distant Stars

Supplements and Credits

Supplement the videos with "OpenStax Astronomy"

01: Stellar Spectral Classification

Here we learn what the dark lines in the spectra of stars mean, and the history behind their understanding.

02: Parallax and Proper Motion

The stars move in many ways. They are not fixed in the sky, but changes slowly over the centuries.

03: Binary Stars, Visual and Spectroscopic

This is the first of two videos about binary stars and their applications. We learn that there are many types of binary star, and some of the most important alre very near to us.

04: Binary Stars Again: Eclipses, Masses and Planets

Binary stars are some of the most important stars to study, as they are the gateway to astrophysics. We can determine their masses and we can determine many other things about them. So, here we chat more about spectroscopic and eclipsing binaries, and how a planet about the size of Earth was found orbiting the star nearest to the Sun.

05: Binary Stars 3: The Mass of Proxima b and Stellar Masses

We use the data from the Pale Red Dot's discovery of a planet around another star to show exactly how we link together the observational data of radial velocity observations to give us the mass and radius of a planet orbiting a distant star. We can't see the planet, but we see its effects. Therefore, we can deduce its properties. We use this to emphasize the importance of learning the masses of the stars.

06: The Hertzsprung-Russell Diagram

This is the most fundamental tool in all of astrophysics. It cannot be understated that this tool basically invented astrophysics, and can even be replicated with amateur-class telescopes.

07: Stellar Radii

The sizes of stars are not just their masses, but their physical diameters, or more useful, their radii.

08: Stellar Mass, Luminosity and Lifespan

Now we get to some real meat of astrophysics. We discuss the relationship between mass, luminosity and lifespan of main sqeuence stars. It is an amazing discovery that mass is known to be tictly correlated to luminosity for M-S star. And for M-S stars, the luminosity is tightly related to spectral type. So, just get the spectrum, and you know the mass!

09: Spectroscopic Parallax

All of astrophysics depends on knowing accurate distances. Here, we see how knowing the distance to a well-studied, nearby star cluster can help us begin to determine the size scale of the Universe. We see how parallaxes, and brightntesses in standard filters can get us all the way out to extremely far distances, and teach us about the nature of those distant places.

10: Star Clusters and Stellar Evolution

Star clusters are elegant and pretty things to see in a telescope, but that's not the whole story. We know that stars must change as they run out of hydrogen to burn in their cores, and those deep changes in the core of stars have observable consequences. So, we use HR Diagrams to map the changes and enormous computer simulations to test the physics.