The appearance of the great range of brightness among star0 4.qf9pm*b3s7 /vxa v odhlxbs is due to

  The absolute luminosity for most stars depends on thec+p zcq0*v2fn

  Four different main-sequence stars are colored blue, orange, red, and yellow. y;u2l r;5bjx 8pzvy+w What is they;xw82lb;p5yjv+zur ir rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot (1im.gz,jr j uof

  A white dwarf star with a mass equal to that of ztp:/ ,bxw)px9ifw/ fp-35lyv4n nitthe Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse intoh xk4+aj )xykfr:8i5r a white d4 )iafk k5yx8rhj:r+xwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always result csd4 e txq7(v)2 mwqr5do(; ikin

  Black holes

  Pulsars are rapidly spin8*v-9yf ibecq6qib z 6ning

State Einstein's principle ,ueuani z43d:72r qd vof equivalence.

  The Schwarzschild radius of a black ho uddtb2vvdla4*q*.- qk (w; xvle is that radial distance from the center of a sphere within which not even light ca aqq- ( w;vdd*.x2tbdv uvkl*4n escape. It was first discovered 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 waveleni:z1-6upp/a tpozehrj o6 m09gth in the visible, and the source is moving away from us, the color of the light appears to us to be s9iamj6ozr:pte /up 6-0o pz1hhifted toward the

  The cosmic background radiation correspondses)eni :k-v(ebhzd8 ) to a temperature of about

  The Sun has apparent brighmti.29cv : uq1ece y :zjg2a-atness 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 luminosity equal to that of the0ac alz l+ui v.dq(k71 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 radi+j6 h( f3.z).bsr s5jvwxzqm pus 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 a ;yagojt6 c 3k6mean 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 angle for Proxima Centauri, which is Earth'ca 3xvd*kp 74ss nearest star at 4.34k vd*pas7x 3c ly?

  The apparent brightness of a star is zifo:z-qrg.mgdij z*80 ;dy 3 $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universy9i )uv k5/tuve is 1/H, where H is the Hubble constant.5 vtuu/ik )yv9 Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving*w 2d1 yfzjakb58 ek4vk7 -doo away from us at 1.0% of the speed of light, how far away is it from u*4zj2ky-okb d1 dka ew7f5vo8s?

  Estimate the speed of a galaxy that is 10 billion light-yg x 2a q*dw/xk*s9 :(zennq3lqears away.

  Estimate the observed wavelength fygah -ps t).n0erk ;7lor the 656 nm line in the spectrum of a star which is 100 mingak- 7l. pthe yrs);0llion light-years from us.

  About 1 ms after the Big Bang, thepu4ee8*do2y i temperature of the universe was about 1013 K. What energy (i i*eop4 8dyu2en eV) does this correspond to?