Star Birth & Basics
This is a large cloud of gas and dust in space where all stars begin their lives.
What is a nebula?
This is the process where two lighter atoms join to form a heavier one, releasing massive amounts of energy.
What is nuclear fusion?
Our Sun is currently in this stable, middle-life stage where 90% of a star's life is spent.
What is the main sequence?
A high-mass star is defined as having more than this many times the mass of our Sun.
What is two (2x)?
The H-R Diagram plots stars based on these two main characteristics.
What are temperature (or color) and luminosity (or brightness/absolute magnitude)?
Gravity is the force that pulls particles of gas and dust together to form this "baby star," which is not yet hot enough for nuclear fusion.
What is a protostar?
In the core of a star, hydrogen atoms fuse together to create this heavier element.
What is helium?
This is the red, expanded stage of an average star that occurs after it runs out of hydrogen fuel.
What is a red giant?
When a massive star runs out of fuel, it collapses and then explodes in this spectacular event.
What is a supernova?
On an H-R Diagram, stars that are hot but dim are found in this corner (usually White Dwarfs).
What is the lower left?
This fundamental force is responsible for the formation of stars, planets, and even our entire solar system.
What is gravity?
A star is stable when the outward energy from nuclear fusion perfectly matches this inward-pulling force.
What is gravity?
After a red giant sheds its outer layers, it leaves behind this "ghostly" cloud of gas and dust.
What is a planetary nebula?
This is a final stage for a massive star; it is so dense that it collapses every proton into this neutral particle.
What is a neutron star?
As you move from right to left on the x-axis of an H-R Diagram, the star’s temperature does this.
What is increases (gets hotter)?
Stars are primarily made of this element, which they use as fuel during the main sequence stage.
What is hydrogen?
Scientists can tell a star is getting older when it contains more of this element and less hydrogen.
What is helium?
This is the final, white-hot, dense core left behind at the very end of an average star’s life cycle.
What is a white dwarf?
If a star is massive enough, its gravity is so strong that not even light can escape its pull.
What is a black hole?
These stars are found at the very top right of the H-R diagram because they are both very bright and relatively cool.
What are Supergiants (or Giants)?
To become a "true" star, the core must reach a temperature of at least this many degrees Kelvin to start nuclear fusion.
What is 10,000,000 (10 million) K?
When a star begins to die and expand into a giant, it starts fusing helium into this element, which is a building block for life.
What is carbon?
Compared to high-mass stars, low-mass stars have a lifespan that is much _______.
What is longer? (They burn fuel slower).
Massive stars produce these heavy elements, like oxygen and iron, which are eventually blown into space to form new planets.
What are elements (or metals/heavy elements)
This term refers to how bright a star actually is from a standard distance, rather than how bright it looks from Earth.
What is absolute magnitude (or absolute brightness)?