Interstellar extinction

Definition

Interstellar extinction is the dimming of light from stars and other celestial objects caused by interstellar dust and gas. It results in the absorption and scattering of light, making distant objects appear fainter than they actually are.

5 Must Know Facts For Your Next Test

1. Interstellar extinction affects all wavelengths of light but is more pronounced at shorter (bluer) wavelengths.
2. The amount of extinction is quantified using the term 'extinction coefficient' or 'A_v', measured in magnitudes.
3. Extinction causes stars to appear redder than they are because blue light is scattered more effectively than red light, a phenomenon known as 'interstellar reddening'.
4. Astronomers use infrared observations to study regions heavily affected by interstellar extinction since infrared light penetrates dust more effectively.
5. The presence of interstellar extinction can significantly alter the observed luminosity and distance measurements of celestial objects.

Review Questions

• What causes interstellar extinction and how does it affect the appearance of celestial objects?
• How does interstellar extinction impact the observed color of stars?
• Why do astronomers use infrared observations when studying regions with high levels of interstellar extinction?

Related terms

Cosmic Dust: Microscopic particles in space that contribute to interstellar extinction by absorbing and scattering light.

Interstellar Medium: The matter that exists in the space between stars, composed mainly of gas and dust.

Reddening: The process whereby starlight appears redder due to scattering by interstellar dust, closely associated with interstellar extinction.