The appearance of the great range of brightness among stars is du q5l:o 7aoyph8. qfbhgu2yfam cs20 5-e to

  The absolute luminosity for most stars depend v aeknt1jb0 jw)j/65vwv4df9s on the

  Four different main-sequence stars are colored blue, orange, red, bnc+1l3:c gt jand yellow. What is their rank from coole:lcbj nc 3+1gtst to hottest?

  A Hertzsprung-Russell diagra713*v). gdzod xu *ouow7r wksm shows stars on a plot of

  A white dwarf star with a mass equaq()wb 6b qqf.q4q dfn.l to that of the Sun is about the size of

  The Chandrasekhar limit of stellb5 wyh 0v5o29jz8qu8 cf:cmjuar mass (below which a star will collapse into a white dwarf) is, if the mas59q wjuvc :mz 285cfhby 0oj8us of our Sun is M, about

  Supernovas are thought to always rg(o:gh paqeyw ,q::m xi :x;,besult in

  Black holes

  Pulsars are rapidly spinnini(qz,4hxxq f90+ m lu+p3boeig

State Einstein's principle ogf vj h9ps /h3uh97:lyf equivalence.

  The Schwarzschild radius of a black hole is thrdypo-)xz h+d1z+h:qn6 g4vn at radial distance from the center of a sphere within whic ) +g1pznx- dodyh:vnzh+64qrh not even light can 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 w9 xj.v;wcrf d:avelength in the visible, and the source is moving away fr:wd vxc;.j9f rom us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a tempersa u ztb5ln-t2/(zu ,xature of about

  The Sun has apparent brig* bmap3x e9)czhtness 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 luminosityqyrjt)l a 3du2*dl5l 9 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 mea7):ute*9r* a/9i +v7 fzul.f klxi vguz0tycnn 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 km?

  The Earth's orbit has fz y w(srl45rt(sz*j a, snopd50:p-s 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 angle for Proxima Centauri,zvsx hrfpv+d3)r6)( 5g6uicw d )xo0s which is Earth's nearest star at uzxc pvv5 oxr+)fwdhi )6rgs(s 03d)6 4.3 ly?

  The apparent brightness of( ky; wc zg2kjo+85afd 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 agev.mdma /f 3 e(sdi.l ckl/ssxy1v- k6) of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, esmys fedavkc-1i.)vl s ( .m3l6ks/d/xtimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, howag9ts+d/vxpsu9b x,l ivk+ ;hw8*w a , far away is itw;g tpd i8x,+hlb w9xkv+9*,s/ vsaua from us?

  Estimate the speed of a galaxy tgz(topdw /kj-vw *6l e4h zj3) n)a4rzhat is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star hf 7j zwpza -9 h(9r(4hmm(qlow mwo(rz 9mjhz4h- (p(7al qfh9hich is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of zs6glc 2/ac4 wthe universe was about 1013 K. What energy (in eV) doe2l6g4wcz c/ sas this correspond to?