2021 astro p2 Flashcards
What type of telescope has a hole in the centre of its objective
Cassegrain Reflector
Describe a method astronomers have used to gather evidence for the existence of black holes
-Observing 2 identical galaxies
-Due to gravitational lensing
-As black holes’ gravity causes light to bend around it
State one difference between a binary star system and a double star system
Binary star system- stars are gravitationally bound to eachother
Double star system-stars are not gravitationally bound but appear to next to eachother when viewed from earth
Describe transit method
exoplanet causes regular dips in the star which it orbit’s apparent magnitude when it transits the star. this is only possible if the exoplanet orbits its star inline with earth
State 3 surface conditions on an exoplanet that could support life
-liquid water available
-suitable temperature range
-suitable gravity
-suitable atmosphere
State 2 physical properties of a neutron star
possible answers:
-made from neutrons
-small
-very dense
-high surface gravity
-strong magnetic field
-rotates fast
-can produce a beam of radio waves
Describe how astronomers can observe neutron stars
-Detected using radio waves
-regular pulses of radio waves indicate a neutron star
What is the most common element in gas giants?
Hydrogen
What are the main componenets of planetary rings?
ice, dust, water
Describe how the roche limit can be used to explain the formation of planetary rings
-point at which tidal gravitational forces become greater than elastic forces
-body gets pulled apart by tidal gravitational forces
-remaining matter continues to orbit the planet
Define ‘local group’
-group of galaxies
-near the milky way
-that are gravitationally bound to each other
Why can’t ground-based telescopes be used to estimate a star’s spectral type
-(using figure) observed peak wavelength has changed
-colour of star will appear to change
-star will appear redder
-means we will incorrectly measure star’s surface temp
-meaning incorrect classification
which part of the HPR diagram has the stars with the highest mass
top left
Explain why the heliocentric parallax cannot be used to measure the distance to a galaxy
galaxy is very far away
so angle is too small to measure
how do you calculate the angle a star appears to move to us in 6 months
sin (trigonometry) the double the angle
