Lecture #11 Flashcards: Stellar Types and Measurements

This set of flashcards covers key concepts from the lecture on stellar types, measurements of brightness, parallax, and spectral classification.

What defines what happens in a star?

The total mass of that star.

What is apparent brightness in astronomy?

The amount of energy per second per square meter that falls off from a light source.

What is the luminosity of a star?

The total energy emitted by a star per second.

What is parallax in the context of astronomy?

A method used to measure the distance to stars by observing their apparent motion against background stars.

How does distance affect apparent brightness?

According to the inverse square law, apparent brightness decreases as distance increases.

What does the magnitude system measure?

The brightness of stars, with apparent magnitude being what we observe and absolute magnitude defined at a standard distance.

What unit of distance is defined by the parallax angle?

Parsec.

What is the temperature of the surface of the Sun?

About 5,800 Kelvin.

How is the spectral type of a star determined?

By analyzing the absorption features in its spectrum, which relate to its temperature.

What are the main sequence stars mainly composed of?

The majority are M-type stars or red dwarfs.

What is the relationship between temperature and luminosity in the Hertzsprung-Russell diagram?

Hotter stars are more luminous, while cooler stars are less luminous.

What is a binary star system?

A system where two stars orbit around a common center of mass.

What is the significance of the diameter of Earth's orbit in measuring parallax?

It's used as the baseline for measuring the angle of parallax.

Who created the original magnitude scale?

Hipparchus in 129 BC.

What was the importance of the Gaia mission?

To measure parallax down to very small angles to map the motion of stars.

What is the main characteristic of O-type stars?

They are the hottest stars, with surface temperatures up to 50,000 Kelvin.

What is the formula used to measure distances based on parallax?

Distance in parsecs is equal to 1 divided by the parallax angle in arcseconds.

What is the role of spectroscopy in studying stars?

To measure the surface temperature and composition of stars based on their emitted light spectrum.

What happens to absorption lines in hotter stars?

They show more ionization and fewer molecules.

What does the slope of a star's light curve indicate in an eclipsing binary system?

It indicates the relative brightness changes as one star passes in front of another.

Who was Annie Jump Cannon?

An astronomer who developed the spectral classification system OBAFGKM.