The appearance of the great range of brightdosa; j :(dxnrr/phh+et0*c jen7 4m1ness among stars is due to

  The absolute luminosity for most star 4ii)ytlu*i;gs depends on the

  Four different main-sequence starmsblbl+m6); ; c49zfvf po i8cs are colored blue, orange, red, and yellow. What is their rank from coolest to hopvf )ib8;olfcsm;z m46l9+ bcttest?

  A Hertzsprung-Russell diagram shows starys.6qk s +da8ptol9r *s on a plot of

  A white dwarf star with a mass equh0d xssql zru(* w+*ey8b1t +aal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapseyspu8 o 8y-wzrppt 3;0 into a white dwarf) is, if the mass of our Sun is M, abou-pouy;p 8rwzst 0p 3y8t

  Supernovas are thought to s53 ;goz2 asxvalways result in

  Black holes

  Pulsars are rapidly spini:(p6o; -r4z0i7xenppbc n zb 7b8mcm ning

State Einstein's principle 9*7wu.snk fegi73me lof equivalence.

  The Schwarzschild radius of a black hole is that radial disrxs g- yr;0yw1tance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in r-yx1 s; yrgw01916 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 sourc(u/r9teo,p6s jg). dqa tsw6ce emits light of a particular wavelength in the visible, and the source is moving away from us, the p 6.qouc es/gt)djw(r6a 9,stcolor of the light appears to us to be shifted toward the

  The cosmic backgrouno)oj1gkjo2j 2 *t+qpzd radiation corresponds to a temperature of about

  The Sun has apparent brightnep5m)2)xs5dkx(eh d uf):jpu kh e(p +hss 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 luminositt j* p:a4mo0ugy 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 aoe.bzrcxk -b dge8vk8wkr/3 + txt4u(.na /c/ 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 km?

  The Earth's orbit has a meanup2v 1tkc 1 osezukhdr;/ x0400bd p6n 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 E*lt k 9tx+:hfvarth's nearest star at 9fxkt+l*h: vt 4.3 ly?

  The apparent brightness of 6tba8 hoe21ad z(yf:m01fwq d 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 ajwe f k-4wnz:.pproximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/4zjwfew:n- . kMly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, hi (a1 aa)6-8mr o3 wh(jdwpxugow far away is it fro-aw1w dgu3j pi6mar8 (ax()o hm us?

  Estimate the speed of a galaxy thag )2tn mlab:y5t is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the specm tet*tt 2,v;sew8a83 ,jxn fptrum of a star which is 100 million light-years fromt*tjw e t;pat882,,ne smf3xv us.

  About 1 ms after the Big Bang, the temperature of the universe was aboutsnu ,z 3 7eq ltj8w-kw+be7.kc 1013 K. What energy (in eV) does this wwke -8bts7+e zc7,qnk. ju3l correspond to?