Flashcards in Chapter 6: Stars Deck (21):
name two properties of thermal radiation
1) hotter objects emit more light per unit area at all frequencies
2) hotter objects emit PHOTONS with a higher average of ENERGY
what is the composition of the sun star
70% hydrogen 2% helium 2% other elements
What do you do when you don't understand data?
Why are the stars spectra different?
because of their temperature. stars are prertty much all alike in chemical composition (hydrogen, helium etc). starts show different spectra soley on temperature changes
a low star mass--> low gravity --> decreased fusion rate--> low temp and low luminosity.
Likewise, high mass star --> high gravity --> increased fusion rate ---> high temp and high luminosity.
What type of diagram explains this relationship?
Hertzsprung-Russell Diagram: The main tool for showing the easily observable characteristics of stars; temperature and luminosity.
Another word for "fusion rate"
consumption of mass.
Would a larger star die faster than a low mass star or vice versa?
larger star dies faster because they have an increased fusion rate, meaning that there is a larger consumption of mass occurring.
What does the H-R diagram plot?
plot luminosities of stars (measure brightness via telescopes and use inverse square law to compare distance star is away. Find distance using parallax) vs their spectral type.
How do you determine how far away a star is?
not burning hydrogen yet. Can be seen in infrared spectrum.
Luminosity depends on size of the star (radius) and temperature of the star
**stars with lower T and higher L than main-sequence stars must have larger surface area and hence are brighter
Relatively Low T (red) and relatively large L, pretty big R (giant)
What star is this?
What is white dwarf?
super dense smaller star resulting from super nova from dying star
Equation for luminosity:
On exam: given L vs T graph Where are the least massive stars?
Lower portion of the graph
Where is the sun?
middle of graph
Where are the largest stars on the L vs T graph
the largest stars have to be the coolest and most luminous stars and therefore hav≥…ÚÚÚÚÚ≥/e the highest radius. Should be on the top of the graph. (top right corner)
what is a main sequence star
Temperature can be determined using wave length- short wavelength (more blue)= higher temperature
Luminosity is dependent on temperature and radius of star