Classificati on HR diagramStar clustersTermsLife cycle Life Cycles 2 $ 200 $ 200$200 $ 200 $400 $ 400$400 $ 400 $600 $ 600$600 $ 600 $ 600$600 $800 $ 800$ $ 800$800 $ 1000 $1000 $ 1000 $ 1000 $ 1000$1000

$200 Temperature The star's color index is a quick way of determining its

$400 Sun The most famous G type star is:

$600 A white dwarf Which is hotter, a main sequence star with an ablsolute magnitude of M=8 or a white dwarf?

$800 It’s mass What is the single most important characteristic in determining the course of a star's evolution?

$1000 Type G2 star, middle of HR diagram-average size and luminosity, end of life will be white dwarf, only known star to support a planet with life. Why is our star (the sun) frequently referred to as an “average” star? Compare the important physical characteristics of the Sun with the most common types of stars.

$200 About the middle of the main sequence On the HR Diagram, the sun lies where?

$400 At the top right of the diagram Where on the H-R diagram, are red giants like Betelgeuse?

$600 In the lower left of the diagram On the HR diagram, white dwarfs are where?

$800 Luminosity and absolute brightness The HR diagram plots ____ and ________ against spectral type and temperature

$1000 On an H-R diagram where would a protostar lie in comparison to the main sequence? Above and to the right of the main sequence.

$200 The stars are in old age (Red Giants) and there are hundreds of thousands to millions of stars in a cluster. Describe globular star clusters

$400 Massive blue main sequence stars The brightest stars of a young open cluster will be

$600 Red Giants In globular clusters the brightest stars will be

$800 Why are star clusters a great way for us to study star evolution? Stars that are in clusters are of similar age, (also composition and distance) from Earth.

$1000 Collisions and physical interactions that can include mergers of object. What can occur in star clusters because of the number of stars that are close together.

$200 Brown Dwarfs A cloud fragment too small to form a star is called a

$400 Hydrogen (molecular) The most common molecule in a molecular cloud is

$600 Gravitation What is the force that keeps a main sequence star from blowing apart?

$800 O type What spectral type of star is most recently formed if it is still around today

$1000 The more massive the faster it uses up its fuel and the shorter its lifetime What is the relationship between star mass and how long it lives?

$200 The igniting of nuclear fuel at 10 millionK What process marks the birth of a new star (protostar to an actual star) ?

$400 Why is it hard to study the life cycle of one star? Stars live too long to be observed from birth to death

$600 It fragments into smaller clouds that form into many stars How does an interstellar gas cloud first begin to form hundreds of stars

$800 Luminosity decrease and temperature increases What happens to luminosity and temperature as an object plotted on the HR diagram moves through stages 4-7

$1000 Outline the process of star formation from interstellar cloud to main sequence An interstellar cloud is disturbed and begins to gravitationally collapse, fragments,It heats up and spins faster. When the core temperature reaches 100 mill K, nuclear fusion begins (H into He). When outward pressure equals inward pressure the star enters the main sequence.

$200 A reflection nebula is cause by Starlight scattered by dust particles

$400 Strong winds develop during which phase of a protostar? T Tauri

$600 When does the T Tauri star occur? When a protostar in about to become a main sequence star

$800 Why is the largest group of stars the main sequence stars? They are young enough to not have most of their hydrogen not fused into helium. They do not evolve off until helium is built up. Most of stars life time is spent as a main sequence star.

$1000 Molecular clouds are cool interstellar clouds(which are bigger than our solar system)they are important because a shock wave can force them to start forming stars. What do we mean by molecular clouds, why are they important and how do they lead to star formation?