Stars Flashcards
What is the definition of one parsec?
The distance at which a star will give a parallax angle of one arc second.
What is the definition of absolute magnitude?
The apparent magnitude of a star if it were located 10 parsecs away from Earth.
How does the intensity of light change depending on distance away from it?
Intensity is proportional to 1/r^2 (inverse square law)
What is the equation involving distance, apparent magnitude and absolute magnitude?
M = m +5 - 5logd
Describe the nature of neutron stars.
Electrons forced inside the nucleus and combine with protons to form neutrons. Sea of free nucleons exert a pressure known as neutron degeneracy pressure.
What stages does a star with solar mass go through?
- Protostar
- Main sequence star
- Red giant
- Planetary nebula
- White dwarf
What stages does a star with extremely large mass go through?
- Protostar
- Main sequence star
- Red Super Giant
- Supernova
- Either neutron star or black hole
Describe the nature of black holes.
Formed when extremely massive stars explode in a supernova - neutron star collapses to zero volume and infinite density. Region around black hole where gravity is so great that light can’t escape is called the Schwarzschild radius.
How did astronomers find evidence for neutron stars and black holes?
Neutron stars - Neutron stars rotate very fast producing spiralling electrons
Black holes - X-ray source due to accretion discs from orbiting binary companions
What are the spectral classes and what temperatures and colours are associated with each?
O - 50 - 25 thousand K - Blue B - 25 - 11 thousand K - Blue A - 11 - 7.5 thousand K - Blue/White F - 7.5 - 6 thousand K - Green G - 6 - 5 thousand K - Yellow K - 5 - 3.5 thousand K - Orange M - less than 3.5 thousand K - Red
Describe the H-R diagram (including axis scales)
Main sequence down middle, red giants in top right and white dwarfs in top left.
Y-axis is Absolute magnitude and X-axis is spectral type (temperature), but is an inverse scale (further along you go, colder star is)
How can elements be found using spectrum?
Diffract star light and match absorption lines with corresponding elements absorption lines.
What are emission nebulae, absorption nebulae and open clusters associated with?
The birth of stars.
What are planetary nebulae and supernovae associated with?
The death of stars.
