Astronomy Revision Flashcards
(30 cards)
What is meant by apparent magnitude?
Apparent magnitude is how bright a star appears to be to the naked eye.
What is meant by absolute magnitude?
Absolute magnitude is how bright a star would be if it was 10 parsecs away from Earth.
What is the equation for absolute magnitude?
M = m + 5 - (5 log d)
What does d stand for in the equation for absolute magnitude?
d = Distance modulus formula
What are the 7 stellar types?
O B A F G K M
What is meant by luminosity?
Luminosity is the total energy output of the star per second.
What stellar type is our Sun?
G2
What are all the electromagnetic radiation in the electromagnetic spectrum in order from lowest to highest frequency?
Radio waves Microwaves Infrared Visible light UV X-rays Gamma rays
Where are the red and white dwarfs on the main sequence?
White dwarfs are located in the bottom left (type A), whereas the red dwarfs are located in the bottom right (type M).
What is the rearranged equation of absolute magnitude?
m = M - 5 + 5 log d
What happens to a star if it has a core mass that surpasses the Chandrasekhar limit?
A main sequence star turns into a red supergiant over time, and then transforms into a supernova.
What happens to a supernova if it’s original core mass was less than 3 solar masses?
The supernova would become a neutron star (supported by neutron degeneracy pressure) - a star that doesn’t have a spectral type.
What happens to a supernova if it’s original core mass was more than 3 solar masses?
The supernova would then become a black hole.
Where on the HR diagram is electron radiation found?
Where the white dwarfs reside - the bottom left .
Where on the HR diagram is radiation pressure found?
Anywhere on the main sequence.
What is the main sequence?
A stable stage in the life cycle of a star where nuclear fusion occurs, fusing hydrogen nuclei into helium nuclei. There is a balance between the outwards radiation and the force of gravity pulling inwards.
What is a nebula?
Large clouds of gas (mainly hydrogen) and dust.
Types of nebulae?
Emission nebulae
Reflection nebulae
Planetary nebulae
Dark nebulae
Supernova remnants
The first stage of the proton-proton chain?
1 1 2 0 + 0
H + H —–> H + e + v
1 1 1 1 0
Proton + proton —> Deuterium + positron + neutrino
The second stage in the proton-proton chain?
2 1 3
H + H —> He + Y
1 1 2
Deuterium + Proton —> Helium - 3 + gamma ray photon
(- means hyphen, not minus)
The third stage in the proton-proton chain?
3 3 4 1 1
He + He —> He + H + H
2 2 2 1 1
Helium - 3 + Helium - 3 —> Helium - 4 + 2 protons
What does 1 AU represent (2 points)?
The AVERAGE distance from the Earth to the Sun = 1.5 x 10^8km
How long is a light year in km?
9.5 x 10^12km
How long is a parsec in light years?
3.1 x 10^13km = 3.26 l.y.
