Chapter 20: The Interstellar Medium Flashcards
What is a Nebula?
A general term used for fuzzy objects in the sky (3 types)
What is an Emission nebula?
Ionized Hydrogen (HII) Regions (Glows due to hot stars)
What is a Dark nebula?
Dust cloud
What is a Reflection nebula?
Blue due to light scattering by dust (lower concentrations of dust)
What is the Interstellar medium?
thin Gas and thick clouds of dust between stars mainly made of hydrogen and helium.
What is ionized hydrogen?
HII (H two) emits 656 nm red emission lines called H-Alpha (most intense)
What is cold interstellar gas?
HI (neutral hydrogen) regions. Lower temp clouds that have neutral hydrogen atoms.
When poles are aligned…
It is a higher energy state
When poles are opposite…
it is a lower energy state (more stable)
What is ultra-hot gas?
Explosions from bubbles (plow through to temps of millions of K)
What is a molecular cloud?
cold enough for hydrogen to be in H2 molecules (coldest gas clouds). Dense and appear dark.
What is a site of star formations?
Molecular clouds.
What is Interstellar extinction?
it is what happens when dust blocks visible light from stars. (fainter)
What is interstellar reddening?
it is when dust blocks short wavelengths of light, which are the same size as dust grain, more efficiently. (UV and blue light are absorbed/scattered while red and IR waves pass through) (redder)
What light does dust emit?
infrared radiation
