Stellar Spectrum and Sound Waves Quiz

Stellar Spectrum and Spectral Lines

• Elements emit unique spectral lines (sets of lines)
• Visible lines depend on the element's temperature. Hotter = more spectral lines
• Each atom/ion/molecule has a unique spectral fingerprint. This is a specific combination of emission and absorption lines.
• White light is a mix of all wavelengths.
• Neon light produces an emission spectrum.
• Thermal radiation: Hotter objects emit more light at all frequencies, and photons of higher average energy.

Sound and Doppler Shift

• Doppler shift in sound: Change in frequency when a sound source moves relative to an observer. Source closer = higher frequency (higher pitch); farther = lower frequency (lower pitch).
• Approaching source = shorter wavelengths (higher pitch)
• Moving away from source = longer wavelengths (lower pitch)
• Redshift: Object moving away
• Blueshift: Object moving towards

Stars

• OBAFGKM: Temperature classification sequence for stars, hotter (blue) to cooler (red).

• O – Hottest

• B

• A

• F

• G

• K

• M – Coolest

• Star color defines temperature.

• Mass→Gravity→Rate of Fusion→Luminosity →Temperature (MGFLT)

• Luminosity = Total energy radiated per second at all wavelengths

• Luminosity depends on the star's temperature and size.

• Distance to nearby stars measured by parallax.

• Larger stars fuse faster, die quicker.

• Composition: 70% Hydrogen, 28% Helium, 2% other elements

• Fusion requires high temperature & density.

• Binary stars orbit each other.

• Stars form from nebulae, die in a supernova.

• Star evolution: Nebula-->Main Sequence -->Red Super/Giant -->Blue Super/Giant -->White Dwarf

• Main sequence = stable stars like our Sun

The Sun

• Sun's diameter = 109 times Earth's diameter.
• Sun's mass = 333,000 times Earth's mass.
• Hydrogen fuses into Helium in the Sun's core (via the proton-proton chain)
• Nuclear fusion powers the Sun.
• Photons travel through the Sun's interior.
• The journey of photons through the Sun is called a random walk.
• The trip from the Sun's core to us takes 8 minutes.

Sun's Structure

• Inner:*

• Core: Location of nuclear fusion, proton-proton chain, gamma ray production. 14-15 million degrees Kelvin

• Radiative Zone: Energy transport via radiation, 70% of the sun's radius.

• Convective Zone: Energy transport via convection

• Outer:*

• Photosphere: Visible surface of the Sun, 6000 degrees Kelvin, Sunspots located.

• Chromosphere: Layer above the photosphere, hotter than the photosphere, where sunspots are located.

• Corona: Outermost layer, much hotter than the photosphere, source of the solar wind.

• Solar Flares: Occur in the corona

Atomic Structure

• Atom: Fundamental building block of matter, consists of a nucleus (protons, neutrons )and electrons
• Ground state: Electron's lowest energy level.
• Excited State: Electron's higher energy level.
• Ionized: Atom with missing electrons
• Number of protons defines the element.
• Neutrals atoms, have the same number of protons and electrons.
• Isotopes: Atoms with the same number of protons but different numbers of neutrons.