Term
a) What element is necessary to start nuclear fusion?
b) What element is produced by nuclear fusion? |
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Definition
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Term
a) What is the temperature (approximately) of the visible surface of the sun?
b) What is the temperature (approximately) of the core of the sun? |
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Definition
A). 5800 K
B). 15,000,000 K |
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Term
| Name two effects caused by the sun's magnetic field. |
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Definition
| sunspots, solar flares, prominences, coronal mass ejections |
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Term
| Why is solar weather an important phenomenon to study? |
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Definition
| solar storms cause damaging effects on Earth |
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Term
| The only feature on the sun that is visible without specialized instruments is a sunspot. What is a sunspot and why are they dark? |
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Definition
| A sunspot is a Earth sized dark blemish on the surface of the Sun. It is dark because the it is an area that is cooler. |
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Term
| What is the different between apparent and absolute magnitude, and what does each measure? |
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Definition
| Absoulte magnitude is a fundamental property of the star which does not change, whereas apparent magnitude depends on its distance from Earth. Apparent measures a star's apparent brightness when seen at the star's actual distance from the Earth. Absolute measures the apparent brightest of the star at 10 PC from the Earth. |
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Term
| List four quantities about a star that can be determined by knowing only its position on an HR diagram. |
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Definition
| Luminosity, Absolute Magnitude, Surface Temperature, Spectral Class, Mass, Radius |
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Term
| What is the Main Sequence? What basic property of a star determines where it will fall on the Main Sequence? |
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Definition
| The Main Sequence is the well-defined band on the H-R diagram on which most stars are found, running from the top left of the diagram to the bottom right. The mass of the star determines where it will fall on the Main Sequence. |
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Term
| What two spectra classes represent the most common stars in the galaxy? What qualities do stars in these classes have? |
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Definition
| M and K. The M class has strong neutral atoms, moderate molecules and very faint hydrogen. The K ionized heavy elements, strong neutral metals, faint hydrogen. |
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Term
| Can spectral type be determined just by looking at the line absorption patterns of stars? How would the spectra of M and O stars be different? |
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Definition
| Yes they can. The M would strong neutral atoms, moderate molecules and very little hydrogen. The O would have Strong ionized helium, multiple ionized heavier elements and faint hydrogen. |
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Term
| What key event causes a star to begin changing into a Red Giant? |
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Definition
| The change of the core structure to allow hydrogen shell-burning changes the energy balance pushing the atmosphere. |
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Term
| Some stars end life as a planetary nebula, some as a supernova. What property of a star determines which way it will evolve, and why does this make a difference? |
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Definition
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Term
| Describe one way that planetary nebulae or supernova remnants affect the birth of new stars. |
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Definition
| THe shock wave from supernovae can cause gas clouds to collapse producing new stars. |
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Term
| What is a white dwarf? Why are they not very luminous even though they are quite hot? |
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Definition
| A white dwarf is the core of a star which had ejected a planetary nebula. They are not very luminous because they are shining by stored heat and not by nuclear fusion. |
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Term
| How can astronomers use the HR diagram of a cluster of stars born at the same time to determine the age of the cluster? |
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Definition
| It can be determined by measuring the age of the stars that are on the main sequence. |
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