Z

Redshift Analysis

Astrophysics Worksheet 05

OBSERVER:

Astronomical Constants & Formulas

Redshift Parameter (\( z \)):

\[ z = \frac{\lambda_{obs} - \lambda_{emit}}{\lambda_{emit}} = \frac{\Delta \lambda}{\lambda} \]

Recessional Velocity (for \( v \ll c \)):

\[ v = z \times c \]

\( c = 3.00 \times 10^8 \text{ m/s} \)

1. Analyzing the Shift

A hydrogen absorption line normally appears at a wavelength of \( 656.3 \text{ nm} \) (Red) in a laboratory setting. When observing a distant galaxy, an astronomer measures this same line at \( 662.1 \text{ nm} \).

Direction

Is the galaxy moving Toward or Away from Earth?

Calculation: \( z \)

Calculate the redshift parameter (\( z \)).

2. Galactic Speedometer

Using the value for \( z \) calculated in Question 1, determine the recessional velocity of the galaxy in km/s.

SHOW ALL STEPS

Observational Theory

If the Andromeda Galaxy is currently showing a Blueshift, what does that tell you about its motion relative to the Milky Way? How does this reconcile with Hubble's Law that "the universe is expanding"?

Redshift Calculation Worksheet

Redshift Calculation Worksheet