HW 4 – CH 4 – Astronomy Today – Flashcards
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Which of the following type of electromagnetic radiation has the highest energy?
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X-ray
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The Orion Nebula, M-42, is a hot, thin cloud of glowing gas, so its spectrum is:
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a few bright lines against a dark background.
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Which of these is the classic continuous spectrum?
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a rainbow.
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The observed spectral lines of a star are all shifted towards the red end of the spectrum. Which statement is true?
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This is an example of the Doppler effect.
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A neon light (thin hot neon gas in a sealed tube) gives us:
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a few bright emission lines, telling us the gas is neon.
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The Fraunhofer lines in the solar spectrum are actually:
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absorption lines due to the thin outer layer above the photosphere.
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What information about an astronomical object can be determined by observing its spectrum?
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all of the above. a. its radial motion b. its chemical composition c. its temperature d. whether it has a strong magnetic field
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An incandescent light (glowing tungsten filament) produces:
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a continuous spectrum, with the peak giving the temperature of the filament.
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Why are molecular lines more complex than elemental spectral lines?
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Molecules can vibrate and rotate as well.
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The broadening of spectral lines can be caused by:
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all of the above. a. magnetic fields of the star. b. thermal motion of the hot atoms. c. rotation of the star. d. density of the hot medium.
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Which of the following type of electromagnetic radiation has the lowest energy?
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radio
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The three laws dealing with the creation of various spectra are due to:
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Kirchhoff.
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Spectral lines are often referred to as the stars' "fingerprints" because:
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All of these are correct. a. both can be easily categorized. b. both are characteristic of the individual that produced them. c. both are unique to their source. d. fingerprints also consist of individual lines that make a pattern.
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Typical stellar spectra appear as:
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a rainbow, but with some dark lines mixed in.
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What is spectroscopy?
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an analysis of the way in which atoms absorb and emit light
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Spectroscopy of a star can reveal its temperature, composition, and line-of-sight motion.
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True.
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The Doppler effect can reveal the rotation speed of a star by the splitting of the spectral lines.
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False.
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Only a hot, thin gas can produce an emission line.
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True.
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The spectral lines of each element are distinctive to that element, whether we are looking at emission or absorption lines.
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True.
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The absorption lines for a cool thin gas are identical in color and energy to the emission lines of the same gas if hot enough to glow.
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True.
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The red hydrogen alpha line carries more energy per photon than the blue-green hydrogen beta line does.
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False.
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The radial velocity of a star's motion in space can also broaden its spectral lines.
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False.
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Molecular spectra, like elemental ones, involve only the vibration of the particles.
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False.
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A low density gas must be hot in order to produce an absorption line.
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False.
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All wavelengths of light travel at the same speed in a vacuum, and carry the same energy per photon.
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False.
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An X-ray photon has more energy than a visible photon.
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True.
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If a fire truck's siren is rising in pitch, it must be approaching us.
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True.
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The shorter a wave's wavelength, the greater it's energy.
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True.
