11.1 Flashcards
Dark dust clouds are what?
Cool regions of gas that emit no visible light and absorb it from stars behind them and emit radiation primarily in the radio and infrared parts of the electromagnetic spectrum.
Emission nebulae are what?
Hot regions of gas surrounding new born stars
Emission nebulae emit what kind of light ?
Visible
Emission nebulae are often found where?
In dark dust clouds in which stars are forming
The interstellar medium
The matter between stars composed of gas and dust
Can light from the stars penetrate the density accumulations of dust?
Not anymore than a cars headlights can penetrate the fog
A beam of light can only be absorbed or scatter by particles with what diameters?
Diameters comparable or larger than the wavelength of the radiation involved
The obscurantism (absorption or scattering) increases how?
With decreasing wavelength
Obscuration
Absorption and scattering
Typical diameter of an interstellar dust particle or dust grain ?
10^-7 m
