The appearance of the great range of brightn n(zdgf/pb4j744kend8h te .vess among stars is due to

  The absolute luminosity for most stars depenxx. 1 l1bb04g8c o1te d1 -eyi5me.zjxms6ihhds on the

  Four different main-sequence stars are colored blue, orange, red, and yellt1jfmzfrx84 e b;3ko6ow. Wht;4f o ezjxrm 3k816bfat is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a i/e: p87k ,of)qdw fgqplot of

  A white dwarf star with a mass equal to that of the Sun is abo.n0a s3o:+p3m q:gq7qg 3;tsaijel ga ut the size of

  The Chandrasekhar limit of stellar mass wmte ;w.y(wx rx ;cb-0(below which a star will collapse into a white dwarf) iswr-0;ty ew .( w;mcxxb, if the mass of our Sun is M, about

  Supernovas are thought to alwayjgl2 use pr0(muk:.4 ns result in

  Black holes

  Pulsars are rapidly sp8 kl)iodlgatk o oa+fhn(*w-05qa+)tinning

State Einstein's prinmbyl 8 ei0ky*13oi2pn ciple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance fro zbuml: *yg1 rog+r+ezb4 e,r7m the center of a sphere within which 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 masbez7 :y,rom+z+4lr beg g*u r1s 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 py ,r3ol; 2mwn 0 3e2fb5 shs6tuz6nlnbarticular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shifted towar t0bw ;s 3 obln2en32fh ym5ulsrzn,66d the

  The cosmic background radiation corresponds to a temperature of aboua76v(:9n*g4tu i j:2hj sh6 irqtqmys t

  The Sun has apparent brightness hs+owf ;h9 pv ya9bwf)8mz 5)lat 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 tojn au -5glrnh4a*:t9 s 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 raiv.p;g6.k mvi)a/k sndius 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 adelvfdwl 1 38,f 3hbc eij0,-y 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, whi.n g*f3qs :lvzch is Earth's nearest star at 4.3s:ngv q*z3l .f ly?

  The apparent brightnesinp:jseka+lp(;.f t ukr8(o +s of 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 qh h8j3myx:8fv25vi : )ne mjtapproximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/8f vmvj ejq mi5hh82tx:):yn 3Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% l: hdir550rlzof the speed of light, how far away is it h:i0rdl5l zr5from us?

  Estimate the speed of a galaxy that is 10 billion light-yea oexgmk-yyx 8/ 59t .ozx-dpl0rs away.

  Estimate the observed wavelength frk 1bz wgjg/41tg(p/ sor the 656 nm line in the spectrum of a star which is 100 million light-//szgj14 prg(wk1bt gyears from us.

  About 1 ms after the Big Bang, the temperature of thec+hvzbw * qe 99wju:icv*pi+6mi+4t z universe was about 1013 K. Whaj*ehi6vptwc4wvc 9+ 9m+ bziq:uz*+i t energy (in eV) does this correspond to?