1. Astronomy Club 2013
Stars – Part 1

2. Stellar Basics:
How colors and spectral types tell us surface temperatures
How distance is measured
How brightness is determined
How stars are classified into groups by temperatures and luminosities
How stars move
Why are binary stars important
Importance of Variable Stars

3. Stellar Basics:
Question: What do you think exists in the space between the objects we see in the sky?
Question: What is a Star?
Answer: Glowing ball of gas. Mostly Hydrogen & Helium
Question: How many atoms are there per cm3 in space?
Answer:
Number of atoms in 1cc of air at sea level= 10 million trillion
The void between stars: 1 atom per cm3
The void between galaxies: 1 atom per m3
Question: What part of the star tells us about its structure?
Answer: Its surface. What do we call that surface (remember our talk on the Sun)?
Answer: Photosphere. Can we see inside the star?
Answer: No. Thus the Photosphere gives is what we know about the star.

4. Winter Constellations: Orion, Pleiades, Taurus The Bull
Activity:
Get in your groups with your binders
Go outside & find these three constellations
In each constellation discuss:
Which stars are the closest?
Are all the stars in each constellation at the same distance?
Which star is the brightest?
What colors do you see?

5. Stellar Distances

6. Stars: How far away are they?
Question: How do you think distances to stars can be measured?
Process of Astrometry: Astronomic Measuring (BRIEF has tools for you to do this for science experiments)

7. Stellar Distances: Two things to remember: 1 parsec= 3.26LY
To find distance in parsecs, divide the parallax by 1: D=1/p
So what? Let’s apply this!

8. Stellar Distances: Apply what you know
How far away is Proxima Centauri?
Parallax is ”…….Now what?
Use the formula: D=1/p
What is the distance in parsecs?
How many light years away is it?

9. Stellar Parallax from Hipparcos: Name Parallax Parsecs Light Years
Apply what you know
Get into your teams
Orion & Pleiades: Are the stars the same distance?
Using what you know about Parallax, what can you tell the class about Orion and the Pleiades?
Stellar Parallax from Hipparcos:
Name Parallax Parsecs Light Years
Betelgeuse: pc 427LY
Bellatrix: pc 242.9LY
Saiph: pc 267LY
Rigel: pc LY
Pieione: pc LY
Alcyone: pc LY
Atlas: pc 380.4LY
Merope: pc LY
Electra: pc LY
Taygeta: pc LY
Thinking about Orion:
Which star did you say was the brightest?
Is this star the closest? If not, what does this tell you?