The Universe

Flashcards about stars, galaxies, and the universe.

What are stars primarily composed of?

Hydrogen and Helium

What is the process that occurs at the core of a star, generating energy?

Nuclear Fusion

What condition is required for protons to collide and initiate nuclear fusion in a star's core?

Extremely high temperatures (around 10 million degrees Kelvin)

What is the Photosphere?

The surface of a star

What three factors determine the brightness of a star?

Surface Temperature, Size, and Distance

How does the color of a star relate to its surface temperature?

Red stars are cooler, while blue-purple stars are much hotter.

What is the Hertzsprung-Russell Diagram used for?

Stars are at different stages in their life cycle

What is the next stage in our Sun’s life cycle?

Red Giant

What happens when a Red Giant's core runs out of Helium?

The star collapses again, and the outer layers of gas escape, forming a planetary nebula.

Describe the end result of our Sun's life cycle.

White dwarf that eventually cools into a cinder

What is the difference between a Type 1 and Type 2 Supernova?

Type 1 occurs when a White Dwarf gains mass. Type 2 occurs in massive stars when Iron is at the core.

What is a Black Hole?

Collapse of a Neutron Star. The corpse of a very massive star that collapses into space

What does the H-R diagram plot?

Stellar luminosity on the vertical axis and the surface temperature on the horizontal axis.

What is the relationship between mass/luminosity and lifespan on the H-R diagram?

High mass and high luminosity stars have shorter lives, while low mass and low luminosity stars have longer lives.

What are the three main types of galaxies?

Elliptical, Spiral, and Irregular

What is the name of our galaxy?

The Milky Way

What is the Big Bang?

Scientists believe the universe began roughly 14 billion years ago in an event known as the Big Bang.

What is the evidence of an expanding universe?

Red Shifting

What does Hubble’s law state?

Galaxies that are farther away have a greater red shift. The speed at which a galaxy is moving away is proportional to its distance from the Earth.

List the Three possible outcomes for the future of the universe?

Big Rip, the universe will gradually stop expanding and approach a size limit, Big Crunch