The appearance of the great rbc8; d cf2p6tkange of brightness among stars is due to

  The absolute luminosity for most stars depeffc ijl3i u6kl0;7o 9qw*u 2fjnds on the

  Four different main-sequence stars are colored blue, orange, red, and yello: s7 u5dxlkf9fw. Whatl5s7:f fd9k ux is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars 2e f 2osyws.vhh;lc u2t.x4i*,n m)awon a plot of

  A white dwarf star with a mass equal to that of the Suwpk*()x3 9jplh5qkqh)m /a-dudj z q8n is about the size of

  The Chandrasekhar liwc aivq 8:38ypmit of stellar mass (below which a star will collapse into aqyi8v :3a wcp8 white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always resulvevr b7-;**n aaw /ejssp sb8mf-pg*)t in

  Black holes

  Pulsars are rapidly spinniw2v t 8-u psxggqdtce.4t7*r*ng

State Einstein's pri*fb5ifke9lng j :i*d9io2fl fzxre/r:)y0g8 nciple of equivalence.

  The Schwarzschild radius of a black hole is that rad/b 0t b zt8qxzp5pqn;+ial distance from the center of a sphere within which not even light can escape. Itq0bn/ p;+tbztzx 85 qp 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 wa f 4kld; gc(ly0j8l55xs s)uedvelength in the visible, and the source is moving away from us, the color of the light s s e8dfyjul4k;dl5 g5x0)cl (appears to us to be shifted toward the

  The cosmic background radiation x1fm y0 ,biq+dx8p, dkx4b;fhcorresponds to a temperature of about

  The Sun has apparent brightness at Eacy(b: r83yvmgrur :i/rth ($1.5 \times 10^{8} \; km$ 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 the Sun kqrf- icy6+7 i($1.5 \times 10^{8} \; km$ 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 radius oftyjli0gq2lk x6 y j 0:4oe73sh8gi d8q $1.5 \times 10^{8} \; km$. 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 mean radius -i9ztd +cutf, 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's nearest sta,wx- g ,dmn2pqmt+cp. lwrlc :zw.y7)+qt h v+r at 4 wcx)q. + q72t ,wczmpmrv- dg.h+p+ l,wynl:t.3 ly?

  The apparent brightness of a sta,j7i-cc y0hs wr 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 1/H, where H i) 3lcafr* (xifs the Hubble constan( lx 3fcfa*i)rt. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how faz0 cc7-auhw3l r away is it from 7uh0 zw-cca3lus?

  Estimate the speed of a galaxy that is :xmd2l.muzw0 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line i6 t8idv* d0dukik ptei4-n gn:t -lbxld.30 h1n the spectrum of a star which is 1dp-6i8 i.0dldg 03nkuve n*4xt-1ikbtltdh :00 million light-years from us.

  About 1 ms after the Big Bang, the ixbb8z 1y)-cl temperature of the universe was about 1013 K. What energy (in eV) does this correspond - by1czb)x8 ilto?