Chapter 6: Stars Flashcards Preview

Astronomy > Chapter 6: Stars > Flashcards

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?

Classify observations.


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?

use parallax


Proto stars

not burning hydrogen yet. Can be seen in infrared spectrum.


Luminosity depends on size of the star (radius) and temperature of the star

H-R Law


**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?

Red giant


What is white dwarf?

super dense smaller star resulting from super nova from dying star


Equation for luminosity:

L=4piR^2(sigma constant)T^4


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

ordinary star


Wiens Law

Temperature can be determined using wave length- short wavelength (more blue)= higher temperature


Stef-Boltzmann law?

Luminosity is dependent on temperature and radius of star


How long can star live from star to end? how much longer does the star live from now till end?

10 by, 5by