Unit 1 test Stars and Galaxies Flashcards | Quizlet

Name two things that can make a star appear brighter.

Color and size

Two light bulbs of the same size are observed $1\,\text{meter}$ from you. One appears orange while the other appears white. Which is hotter and brighter?

The white light bulb is hotter and will appear brighter.

An object is discovered that appears bluish-white, and its spectrum consists of a series of different colored bright lines. What determines this object's color?

Its composition

What is the easiest way to compare the temperatures of two stars without putting a thermometer on them?

By comparing their color.

What is parallax, and what TWO quantities does it depend on?

Parallax is an apparent shift of an object because of a change in observation points. It depends on distance and baseline.

How are degrees, arcminutes, and arcseconds defined relative to one another?

One degree is $60\,\text{arcminutes}$, one arcminute is $60\,\text{arcseconds}$, and an arcsecond is $\frac{1}{3600}$ of a degree.

In what unit would the parallax of your finger at arm's length best be measured?

Degrees

In what unit would the parallax of the star Sirius as viewed from Earth's orbit best be measured?

Arcseconds

What is a light year?

The distance light travels in one year.

What is a parsec?

A parsec is the distance to an object whose parallax is exactly $1\,\text{arcsecond}$.

HD 25329 has a parallax of $0.054\,\text{arcseconds}$. What is its distance?

$$D = 18.519\,\text{parsecs}$$

Upon what two quantities does luminosity depend?

Size and temperature

How is light produced?

By wiggling or accelerating charged particles.

List the seven types of electromagnetic radiation in order of WAVELENGTH from longest to shortest.

Radio Waves, Infrared, Visible Light, Ultraviolet, X-Ray, Gamma Ray.

List the seven types of electromagnetic radiation in order of ENERGY and FREQUENCY from highest to lowest.

Gamma Ray, X-Ray, Ultraviolet, Visible Light, Infrared, Radio Waves.

What type of spectrum does an incandescent light bulb produce, and what determines its color?

It produces a continuous spectrum (rainbow), and its color is a result of its temperature.

What type of spectrum does a discharge tube produce, and what determines its color?

It produces an emission spectrum (a series of separate bright lines), and its color is a result of its composition.

How does parallax change as the distance to an object increases?

The farther the distance, the smaller the parallax.

If holding a finger at arm's length produces a parallax of $2.5\,\text{degrees}$, what parallax does it display when held closer to your nose?

$$12.5\,\text{degrees}$$

What is the definition of wavelength ($\lambda$)?

The length over which the wave repeats in pattern (meters).

What is the definition of frequency ($f$)?

How often the wave repeats itself (waves per second).

How does a red photon compare to a blue photon?

A red photon has lower energy, lower frequency, and longer wavelength.

What color is light with a wavelength of $4000\,\text{Angstroms}$ ($400\,\text{nm}$)?

Violet

Where would you find a red giant on the HR diagram?

Upper right

If Object 1 gives off most of its light in radio waves and Object 2 gives off most of its light in infrared, which object is hotter?

Object 2