Astro 1500 Trivia - March 7th

The Hertzsprung-Russell (H-R) diagram is a plot of ...

• distance vs temperature

• Temperature vs stellar class

• luminosity vs temperature

• Brightness vs distance

Answer explanation

The HR diagram is a plot of luminosity vs temperature.

Delta Circini is an O-type star and Alpha Centauri B is a K-type star. Which one is brighter?

• Delta Circini

• Alpha Centauri B

• They are the same brightness

• We need more information

Answer explanation

Without the distance to the stars, we cannot know which one is brighter.

The region in the center of the HR diagram that slopes left is called the...

• Normal Stars

• Main Sequence

• Normal area

• Main section

Answer explanation

This area in the center is called the main sequence

Stars in the top right of the HR diagram are usually called...

• Giants

• White Dwarves

• Planets

• O type

Answer explanation

The top right are high luminosity, cooler stars, meaning they have to be very large, as such they are called giants

Stars in the bottom left portion of the H-R diagram are called ...

• Giants

• White Dwarves

• Supernovas

• M types

Answer explanation

Stars in the bottom left are very hot, but low luminosity, so they have to be pretty small.

The sun is a G-type star, with a solar luminosity of 1, where does it reside on the H-R diagram

• With the giants

• With the white dwarves

• On the main sequence

• The sun is not on the HR diagram

Answer explanation

As a G type star, with a solar luminosity of 1, the sun sits right about in the middle of the HR diagram, on the main sequence.

Betelgeuse is an M type star with a luminosity of 80,000 solar luminosities, it sits in the ___ region

• Giant

• White Dwarf

• Main Sequence

• Gas Cloud

Answer explanation

Betelgeuse is a low temperature star, but has a massive luminosity, so it must be enormous

By far, the most common type of star in the universe is a...

• Red giant (High Mass)

• O-type main sequence (Variable Mass)

• Sun-like Star (Medium Mass)

• Red Dwarf (Low Mass)

Answer explanation

Red dwarves are smaller and live much longer than any other type of star, so there are a lot of them

The brightest star in the sky, Sirius, is actually a binary star system consisting of Sirius A and Sirius B. If Sirius A is twice as massive as Sirius B, which star will live longer?

• Sirius A

• Sirius B

• We need more information

• They both die in the 5th movie

Answer explanation

Sirius A will burn through all it's fuel much quicker and turn into a giant star before exploding. Sirius B will slowly burn for much longer.

Other than mass, what determines a star's evolution on the H-R Diagram?

• Temperature

• Composition

• Luminosity

• Distance from Earth

Answer explanation

Composition determines the amount of hydrogen in a star, which also determines how long it will live.