stellar physics
The primary source of energy in stars, this process involves combining hydrogen atoms to form helium.
nuclear fusion
Named after two astronomers, this diagram classifies stars by luminosity and temperature, showing patterns like the main sequence.
The H-R (Hertzsprung-Russell) Diagram
A sun-like star enters this phase near the end of its life, expanding massively as it cools and brightens.
red giant
In the H-R Diagram, stars in this life phase occupy the upper right, indicating they are cool yet very luminous.
red giant
Containing hundreds of thousands to millions of older stars, these dense, spherical clusters orbit the galactic core
globular cluster
This balance between gravitational pressure and outward thermal pressure keeps stars stable over long periods.
hydrostatic equilibrium
Do higher mass stars or lower massive stars burn up their fuel more quickly?
higher mass stars
This colorful shell of gas is expelled by a dying star, often seen in the later stages of a sun-like star's life.
planetary nebula
On the H-R Diagram, this region below the main sequence represents stars that have stopped nuclear fusion, remaining hot but dim.
white dwarf region
This type of star cluster contains a few thousand stars that are loosely bound and often young, like the Pleiades.
open cluster
This limit, approximately 1.4 times the mass of our Sun, defines the maximum mass of a white dwarf before it can collapse into a neutron star.
the Chandrasekhar Limit
Name the 7 Spectral Classes in order
O, B, A, F, G, K, M
After a star sheds its outer layers, it may end up as this dense, Earth-sized remnant that no longer undergoes fusion.
white dwarf
This relationship, illustrated in the H-R Diagram, shows that hotter stars are often more luminous.
temperature - luminosity relationship
What is the standard unit for measuring the mass of stars?
solar masses
(our sun = 1 solar mass)
After hydrogen fusion in the core of a low-mass star ends, what chemical process follows?
This relationship shows that the brightness of a star increases significantly as its mass increases
the mass-luminosity relationship
These sub-stellar objects, often called 'failed stars,' are too low in mass to sustain hydrogen fusion.
brown dwarf
What type of star has a high temperature but a low luminosity?
white dwarf
As a star expands to become a red giant, does the surface temperature increase or decrease?
decrease
The Doppler Effect causes light from distant galaxies moving away from us to shift toward this part of the spectrum, providing key evidence for the expansion of the universe.
the red end of the spectrum / redshift
(Galaxies farther from us have more space expanding between us and them, which translates to higher redshifted light)
This law states that the energy radiated per unit surface area of a blackbody is proportional to the fourth power of its temperature.
the Stefan-Boltzmann Law
What are the 5 steps for the birth of a star?
1. A molecular cloud forms
2. Sub-regions of the cloud called
clumps/cores continue to
collapse and fragment
3. A protostar forms and accretes (accumulates)
mass from its surroundings
4. Accretion of mass stops, and a pre-main sequence star is formed
5. Fusion begins (As the pre-MS star collapses, eventually pressure due to hydrogen fusion
stops the contraction, and the star is in equilibrium)
____ ____ ____ tells us the age of clusters.
Main sequence turnoff
Up to how long can the planetary nebula phase last?
Up to 1 million years.