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Exam 2
| Question | Answer |
|---|---|
| Which theoretical power of an optical telescope is determined by the diameter of the primary mirror or lens? | Light gathering power and resolving power |
| The primary mirror of telescope A has a diameter of 20 cm, and telescope B has a diameter of 100 cm. How do the light gathering powers of these two telescopes compare? | Telescope B has 25 times the light gathering power of telescope A. |
| Is a primary lense longer or shorter than an eyepiece lense? | Longer |
| Which power of a large ground-based optical telescope is severely limited by Earth's atmosphere on a cloudless night? | Resolving power |
| What major problem would be introduced if the reflective coating were beneath the glass surface? | Chromatic aberration |
| What do large diameter, gently curved convex lenses and large diameter gently curved concave mirrors have in common? | Long focal lengths and primary light collectors |
| Which power of a telescope is least important? | Magnifying power |
| To which two electromagnetic bands is Earth's atmosphere most transparent? | Visible and radio |
| Why do the pupils of cat's eyes open wider at night? | To increase light gathering power |
| Why have no large refracting telescopes been built since 1900? | All of the below |
| Why must far infrared telescopes be cooled to a low temperature? | To reduce interfering heat radiation from the telescope |
| Bigger lenses can see dimmer objects. True or false? | True |
| In which device to astronomers take advantage of chromatic aberration? | The prism |
| Why are the sources of cosmic rays so difficult to locate? | They are charged particles |
| What is the primary problem overcome by radio interferometry? | Poor resolving power |
| What advantage do builders of large telescopes today have? | All of the below |
| Which power of a telescope might be expressed as "0.5 seconds of arc"? | Resolving power |
| Which wavelengths are bent by the greatest amount? | Short wavelengths |
| What do CCD chips do better than photographic plates? | All of the below |
| Why are UV telescopes located in Earth's orbit? | Ozone is located high in the atmosphere |
| A single photon of which color has the greatest energy? | Violet |
| What is a disadvantage of radio telescopes? | All of the below |
| In which device is chromatic aberration a big problem? | Primary lenses |
| What can radio telescopes do that optical telescopes cannot? | |
| See through dust clouds | |
| What transition happens when a hydrogen atom absorbs a visible light photon at 656 nm? | Level two to level three |
| What does a hot hydrogen gas emit? | Three spectral lines: red, blue, and violet |
| What does the presence of molecular bands in the spectrum of a star indicate? | |
| Low surface temperature | |
| What is responsible for the sun's surface and atmospheric activity? | Magnetic field |
| Which feature in the sun's atmosphere corresponds to dark filaments? | Prominence |
| Why is the center of a granule brighter than it's edges? | Temperature is higher at the center |
| What evidence do we have that sunspots are magnetic? | Zeeman effect, material arched above sunspots |
| Which layer of sun is responsible for absorption lines? | Photosphere |
| The spectrum of the corona has bright spectral lines of highly ionized elements. What does this reveal? | Corona is very hot, low density gas |
| How are astronomers able to explore layers of the sun below the photosphere? | Measuring and modeling modes of vibration |
| What evidence do we have that granulation on the sun's surface is caused by convection? | Bright centers are hotter, Doppler measurements indicate centers are rising |
| Which is true about granules and supergranules? | They're both due to convection cells in layers below |
| What are trends in temperature and density from photosphere to chromosphere to corona? | Temperature increases density decreases |
| What happens to neutrinos produced in proton-proton chain? | They leave the sun at nearly the speed of light |
| What physical property of the sun is responsible for "limb darkening"? | Lower photosphere is hotter than upper |
| What is the source of the sun's changing magnetic field? | Differential rotation, convection beneath photosphere |
| What solved solar neutrino problem? | Discovery that neutrinos oscillate between three different types |
| Why does nuclear fusion require high temperatures? | All of the below |
| Which direction does the sun rotate? | Counterclockwise |
| What heats the chromosphere and corona to high temperatures? | Fluctuating magnetic fields |
| Which layer of the sun's atmosphere contains cooler low-density gas responsible for absorption lines? | Photosphere |
| What does a Maunder butterfly diagram show? | Sunspots begin at high latitude and move closer to equator |
| Which atomic element has the greatest binding energy per nuclear particle? | Iron |
| What effect does the formation of negative hydrogen ions in the sun's photosphere have on solar observations? | Extra electron absorbs different wavelength photons making photosphere opaque |
| How does the sun maintain its energy output? | Fusion of hydrogen nuclei |
| What is reveled by observing the sun at narrow range of wavelengths within 656 nm? | Structure of chromosphere |
| How much does solar constant vary? | Less than one percent (0.1%) |
| What's the distance to a star with a parallax angle of 0.5 arc seconds? | Two parsecs |
| Which is a correct listing of the stars from largest to smallest? | Betelgeuse, Canopus, Adara, the sun, Sirius B |
| At what distance must a star be to have its apparent magnitude equal to its absolute magnitude? | Ten parsecs |
| To which luminosity class does the mass-luminosity relation apply? | Main sequence |
| A star has one-half the surface temp of the sun and is four times larger. What is its luminosity? | One solar luminosity |
| A star with the same spectral type as the sun has a luminosity of 50. What does this tell you? | It's larger than the sun |
| The sun's spectral type is G2. What is its luminosity class? | Main sequence |
| What info is needed to find the distance to a star whose parallax angle isn't measurable? | Spectral type and luminosity class |
| What are the radius and luminosity of a star classified as G2 III? | Ten solar radii, 100 solar luminosities |
| Start B is observed to be always four times as far away from the center of mass as star A. What does this tell you? | The ratio of star A's mass to star B's is four to one. |
| Which spectral type had the strongest hydrogen absorption lines? | A |
| It is assistant that the luminosity of a spectral type A7 star is approximately what? | Ten solar luminosities |
| The mass of Sirius A to Sirius B is what? | 2.3 : 1 |
| Which luminosity class has stars of the lowest density? | Supergiant |
| The parallax angle of a star and the two lines of sight form a long skinny triangle with a short side of what? | One AU |
| What are the individual masses of star A and star B? | Eight solar masses and two solar masses |
| All stars are mostly hydrogen and helium, but many have no lines. What causes this contradiction? | Electrons are not at proper energy levels |
| Why can smaller parallax angles be measured by telescopes? | Earth's atmosphere doesn't limit resolving power |
| Which binary star is illustrated? | Spectroscopic |
| Why are few red dwarf stars plotted? | They have very low luminosity |
| What's the distance to a star with apparent visual magnitude of 3.5 and absolute visual magnitude of -1.5? | 100 parsecs |
| Which color star has the strongest molecular bands? | Red |
| How can a cool star be more luminous than a hot star? | If it's larger |
| The mass of a spectral type A5 start is what? | 2.2 solar masses |
| Which star has highest surface temperature? | B |
Created by:
mirpoulson