Astro A2 - Cosmology Flashcards
What is red shift and how is it represented
Change in frequency/frequency. Represented with z
What is a binary star system
Two stars rotating about a common center of mass
Describe the light curve of a binary systems
Absolute magnitudes at max when both stars can be seen. Lowest dip is caused by the cooler star passing in front of the hotter star. The mid dip is caused by the hotter star passing in front
Describe the graph of the wavelength of a spectral line of a star in circular star
Sinusoidal graph
What do the peaks and troughs mean on a spectral line of a star in a binary system
Peaks and troughs mean the stars are next to each other. At equilibrium position, an eclipse occurs
What does the data from Hubble’s Law suggest
The universe is expanding, from one common point
What is the age of the universe
1/H (15 billion years)
What was the first use of dark energy
Type 1a supernovae were seen to be dimmer than expected, showing that the rate of expansion of the Universe is increasing. This is due to dark energy
What is the theory of the Big Bang
13-14 billion years ago, the Universe expanded from an extremely hot and dense point and is still expanding
What is CMBR
The left over ‘heat’ from the big bang, the photons having been stretched to longer wavelengths and lower energies. Has a black body curve peak at 2.7k
What is an evidence for the Big Bang involving hydrogen and helium
The Universe fused hydrogen, then expanded and cooled too rapidly for the creation of larger nuclei, resulting in a relative abundance of Hydrogen and Helium (in the ratio of 3:1) spread throughout the Universe. This is consistent with observation
What can you compare the power of a quasar to
The same power output of several galaxies (10^42W)
What are exoplanets
Planets outside our solar system
Why are exoplanets hard to detect
The light from them tends to be obscured by the much
brighter star they orbit, and the planet and star tend to be too close together for
the optics to resolve them
What are the different ways of detecting exoplanets
Radial velocity and transit method
