Space Flashcards
(28 cards)
What is a black body?
A body of matter that absorbs all radiation that lands on it and it can be considered to be the perfect emitter
What does the narrowest peak represent on a black body diagram of emitted light?
Most radiation is emitted at this wavelength
As temperature of a black body increases, what happens to the peak wavelength of radiation emitted?
The peak shifts to the left ( lower wavelength )
What wavelength do really cold objects emit radiation at?
Really high wavelength like radiowaves
What type of light do everyday temperature black body’s emit?
Infrared light
Do stars behave like black bodies?
Yes because they emit a continuous spectrum of radiation
What’s Weins law (black bodies)
For each temperature, there a peak in the radiation curve called the peake wavelength
Define luminosity
Energy radiated by an object per second (in Watts)
What’s the relationship between luminosity and temperature or surface area?
Directly proportional to both
What is a protostar?
Clouds of dust and gas that clump together under gravity
Describe the Hertzsprung-Russell diagram.
Y-axis is luminosity
X-axis is temperature (goes from high to low)
Dwarfs bottom, main sequence middle diagonal, giants high right, super giant very top
Whats a problem with trigonometric parallax?
It’s only applicable to close stars, as when the distance increases the angle become too small to measure.
What is 1° in minutes of arc?
60’
What is a parsec?
The distance the star needs to be for the angle to be 1 second of arc
What are standard candles
Objects which have a known luminosity
How old is the universe roughly
13.8 billion years
What does a high pitch of sound mean
The sound has a higher frequency
What does a louder noise mean?
Large amplitude
How do we know the universe is expanding.
By measuring the redshift of galaxies, astronomers can determine the speed at which they are moving away from us.
Describe the characteristics of a main sequence star.
Constantly converting hydrogen to ugh fusion and maintaining a constant luminosity
Describe how to find the distance of nearby stars.
Use trigonometric parallax go find the angle against the background that a star moves by in 6 months. Use this to find the distance .
Why do large stars have greater luminosity
Surface temperature and area is the greatest. Most massive stars experience high gravitational force. Therefore, high temperature and density in the core. So rate of fusion is greatest.
Explain the conditions required to bring about and maintain nuclear fusion in stars.
- High temperature needed
- nuclei all have positive charge leading to a large repulsive force between nuclei
- at high temps nuclei have KE sufficient to overcome repulsion
- nuclei must get close enough to fuse
- required high density
- collision rate must be high enough to sustain fusion
Why do astronomers have difficulty in making accurate measurements to galaxies or measuring the critical density of the universe?
There’s a large uncertainty in bubbles constant because dark matter creates uncertainty of the values of mass and density.
