Cosmology Flashcards
What is a quasar?
Supermassive black hole surrounded by disc of matter.
As matter falls in, radiation is emitted.
What are exoplanets?
Planets that are not within our solar system.
Why are exoplanets hard to detect?
They are often obscured by the light of their host star.
What are the two methods of detecting exoplanets?
Radial velocity method
Transit method.
What is the Doppler effect?
The compression or spreading out of waves emitted from a moving source.
What is CMBR and how does it provide evidence of the Big Bang?
Cosmological Microwave Background Radiation.
After big bang universe filled with high energy radiation.
As universe expands and cools radiation loses energy and is red shifted.
CMBR is remains of this radiation and has been detected every direction.
How does nuclear fusion provide evidence of Big Bang?
Soon after big bang everything was condensed and hot.
This allowed for fusion of hydrogen atoms into helium.
Approximately 1/4 of all hydrogen were fused.
Resulting relative abundance of He:H ==> 1:3.
Today 75% H, 23% He, 2% other.
How does Doppler shift allow for binary stars to be identified?
When stars travel perpendicular to detector no Doppler shift of light spectrum.
When travelling parallel Doppler shift occurs both ways. (Spectral lines split in two).
How does the radial velocity method help detect exoplanets?
Centre of mass of star and planet causes star to ‘wobble’.
This causes a Doppler shift in light detected from star.
Time period of exoplanet orbit = time period of doppler shift.
How does the transit method help identify exoplanets?
Observing light intensity of a star.
If there’s a regular dip, planet must be crossing in front of star (transiting)
Size and period determined from amount intensity falls and duration.
State the property of quasar that led to its discovery?
High power radio emitter.
