Chapter 30 Science
What is the diameter of the medium sized star, our sun?
1,390,000 km
What are the several types of actual motion that most stars have?
1. rotate on an axis 2. revolve around another star 3.move either to or away from our solar system
To what does the temperature of a protostar increase?
10,000,ooo degrees celcius
What is the general temperature of stars?
2,800-24,000 degrees celcius
How many stars can be seen through telescopes on Earth?
3 billion
What is the speed of light?
300,000 km/s
What is the average temperature of a blue star?
35000 degrees celcius
What is the temperature of yellow stars?
5,500 degrees celcius
What does a nebula consist of?
70% hydrogen, 28% helium, 2%heavier elements.
How long does it take light from the sun the reach earth?
8 light-minutes
How far does light travel in one year?
9.46 trillion km
What is a star?
A ball of gasses that gives off a tremendous amount of electromagnetic energy.
What is a nebula?
A large cloud of gas and dust in interstellar space.
What is a pulsar?
A rapidly spinning neutron star that emits pulses of radio and optical energy
What is the red shift?
A star moving away from earth is a red shift.(longer waves)
What spectra do all stars have?
All stars have dark-line (absorption) spectra-bands of color crossed by dark lines where the color is diminished.
What is the Parallax?
An apparent shift in the position of an object when viewed from different locations
What is the Doppler Effect?
An observed change in the frequency of a wave when the source or observer is moving
What are the two types of motion that is associated with stars?
Apparent motion-noticible Actual-can only be measured with high-tech
How do astronomers direct starlight?
Astronomers direct starlight through spectrographs.
How do astronomers mainly learn about stars?
Astronomers learn about stars primarily by analyzing the light the stars emit.
How can Scientists determine the elements that make up a star?
By studying its spectrum, because different elements absorb different wavelengths of light.
What are Star's made up of?
Different elements in form of gases
Who discovered the pattern of the H-R Diagram?
Ejnar Hertzsprung and Henry Norris Russell
What do the elements in the outer layers absorb?
Elements in the outer layers absorb some of the light radiating from within the star.
What does every chemical element have?
Every chemical element has a characteristic spectrum in a given range of temperatures.
What does H-R Diagram stand for?
Hertzsprung-Russe Diagram
What does a Spectrograph do?
It separates light into different colors, or wave legnths. Light passing through a spectrograph turns the light into a spectrum.
What is Nuclear Fusion?
Nuclear Fusion is the combination of the light atomic nuclei to form heavier atomic nuclei.
Besides the sun, what is the star closest to earth?
Proxima Centuri
What is a quasar?
Quasi-stellar radio source; a very luminous object that produces energy at a high rate.
What is the color and temperature of the coolest star?
Red; 3,000 degrees celcius
What is a circumpolar star?
Stars that never pass below the horizon, and circle
What do the varying color of stars tell us?
That stars are different temperatures.
What is the absorption spectra?
The absorption spectra is a dark line
What is the Blue Shift?
The colors in the spectrum of a star that moves toward Earth.
What do the colors and lines in the spectrum indicate?
The elements that make up the star.
What does the emission spectra do?
The emission spectra is a bright line
Where the electromagnetic energy of a star come from?
The energy comes from nuclear fusion within a star.
What is apparent movement caused by?
The movement of the Earth
How have scientists learned that stars are made up of the same elements that compose Earth?
Through spectrum analysis
What do astronomers use the H-R Diagram for?
To describe the life cycles of a star
What is a neutron star?
a star that has coapsed under gravity to the point that the eectrons and protons have smashed together to form neutrons
What other elements help make up a star?
carbon, oxygen, and nitrogen in small quantities.
What is most of the universe made of?
dark energy
Stars that are very _____ may have more ____ than the sun and still be much smaller.
dense;mass
Less dense stars may have a larger _______ than the sun but still has less ____ than the sun
diameter;mass
What are the different types of spectra?
emission, absorption, continuous
The inner layers of a star are ____, the outer layers are somewhat ______.
hot;cooler
What is the most common element in a star?
hydrogen; Helium is the second most common
As gravity increases in a star, what does pressure do?
increases
As the ___ of an object increases, the distance between two objects________.
mass; decreases
What size are most stars visible to Earth?
medium
What is the apparent magnitude?
the brightness of a star as seen from Earth
absolute magnitude?
the brightness that a star would have at a distance of 32.6 light years from earth
What is a light year?
the distance light travels in one year
What does a Star's dark-line spectra reveal?
the star's composition and temperature.
What is cosmic background radiation?
uniformly detected from every direction in space
What is the main sequence of a star?
where most stars on the HR Diagram lie
