The appearance of the great range of brightness among stars is due -e(jbt3hdw3 q to

  The absolute luminosity for most starsy /fkfjvj 5b2 8zle qg3-3zvf/ depends on the

  Four different main-sequence stars b venh-kw;4-xare colored blue, orange, red, and yellow. What is their rank from coolest e nkxhv- 4;-bwto hottest?

  A Hertzsprung-Russell diagram shows stars c zr ,f;ju0(hpon a plot of

  A white dwarf star with a mass equax*je)/4icc4(rr r nw3y(6mc4 k zdgw pl to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collaps ai r7nl;2enc/e into a white dwarf) is, if the mass of our Sun is c;nnerl 2ia /7M, about

  Supernovas are thought to alwr5c7 gx9s1 abuays result in

  Black holes

  Pulsars are rapidly spinningdc(*z6z :v2 7w uzldl+0ystig

State Einstein's principl i9tbh- bwasmgv0+6+7 v jlnw ogmh2,9e of equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cn1u s.u rep7f,enter of a sphere within which not even light can escape. It was first discovered 7,nfp u1res.u mathematically by Schwarzschild in 1916 after Einstein published his general relativity theory. It can be calculated from a star's mass M as: $R = 2GM/c^2$. Take the radius of both stars A and B as the Schwarzschild radius. If the mass of star A is twice as much as the mass of star B, the average density of star A, compared to star B will be

  When a distant source emits light of a particular wavelength in the )s 46hdrn1hhl visible, and the source is moving away from us, the color of the light rl46h1nd hsh)appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of aboymjuek2nn7 k+2q f:i 0ut

  The Sun has apparent brightn2 jes;,(w(nltqsa/.jb*m mv1s bi l3eess at Earth ($1.5 \times 10^{8} \; km$ away) of B. What would be the apparent brightness of the Sun at Pluto, which is $6.0 \times 10^{9} \; km$ from the Sun?

  A star has absolute l avhhb;.:n. qv.kw*k8zlj)spvfr6* fuminosity equal to that of the Sun ($1.5 \times 10^{8} \; km$ from the Earth) but is 10 pc away from the Earth. By what factor will it appear dimmer than the Sun?

  The Earth's orbit has a mean ragy2d2tf5lda (dius of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in km?

  The Earth's orbit has( /pc19vg6 7nvkabhytb 4l x;h a mean radius of $1.5 \times 10^{8} \; km$. Over a six-month period, the apparent position of a particular star varies by $0.00014^{\circ}$ due to parallax. How distant is the star, in ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax a d(3qbw mdu3; qj2u:irc 7mt3rngle for Proxima Centauri, which is Earth's nearest star at 4.3:(qj2w33d mc uur mqb;dir t73 ly?

  The apparent brightness ofwwtsj(t eg ta,/d ks:e3 8p7,b a star is $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universe is i;)pm3bhm 4l5e 3ro .ndq+ qs. x jkl9yn)u;xv1/H, where H is the Hubble constant. Taking H = 20 3p q.om)lrl5kny.bjxn s9 mq;)d 4;3euhivx +km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving awa:s 63dms2py i5a1qs 7etlt *pe*lm/lu8f*lmc y from us at 1.0% of the speed of light, how far away is it frm*s*/yiptl* m l2c8qd :lsf3te15as7 6me pluom us?

  Estimate the speed of a galaxy 4hyoky )*/gfrn+-+ 6 fssk nlpujdw3--g9lya that is 10 billion light-years away.

  Estimate the observed wavelength for krha4la1de.v0: k )r 62rqkjvthe 656 nm line in the spectrum of a star which is 10j01q)harvkk4lr 6rv 2 .d ek:a0 million light-years from us.

  About 1 ms after the ohuapavj0,p l*; 7xb j sc5n58 y-grq;Big Bang, the temperature of the universe was about 1013 K. What energy p* l ,u7a5j5a;0n-pscyjv8rh qo;gbx (in eV) does this correspond to?