The n=3 to n=2 transition of hydrogen is normally at 656.3 nm . If it is detected from a star at

step 1 ionized hydrogen captures an electron right into the first quantum state. So we have a transitio

The n=3 to n=2 transition of hydrogen is normally at 656.3...

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Doppler Effect

The Doppler effect describes how the wavelength (and frequency) of light changes due to the motion of the source relative to the observer. In astrophysics, when a star moves towards or away from Earth, its spectral lines are shifted to shorter (blueshift) or longer (redshift) wavelengths, respectively. This principle forms the basis for measuring the motion of stars and galaxies using light.

Radial Velocity

Radial velocity is the measure of the speed at which an object moves along the line of sight of an observer. By observing the Doppler shift in the spectral lines of an astronomical object, one can determine the radial component of its velocity. A shift toward shorter wavelengths indicates that the object is moving toward the observer, while a shift toward longer wavelengths indicates it is moving away.

Spectral Lines

Spectral lines are specific wavelengths where atoms or molecules absorb or emit light, corresponding to electron transitions between discrete energy levels. These lines act as reliable markers since their rest (laboratory) wavelengths are well known, allowing astronomers to detect and measure any deviations due to the Doppler effect. This measurement is essential for determining the motion of stars and other celestial bodies.

Please give Ace some feedback