The appearance of the great range of brightness among starsi ;-lljyc7s 9 e4eq.jr is due to

  The absolute luminosity for most stars dependse,;cc.h-srza 5 tcbs. on the

  Four different main-sequence st)kke cvea*g-a 6v 1*zpars are colored blue, orange, red, and yellow. What is their rank from coolest to hotc 1ga-k z)kv aev*pe*6test?

  A Hertzsprung-Russell diagram shows v .k-qbav(( hrstars on a plot of

  A white dwarf star with a mass equal to that of:zz) l0d syf1 p,aut8us+5hbp the Sun is about the size of

  The Chandrasekhar limit of stellar mass (belorku)2vto i b11( 0usekw which a star will collapse into a white dwarf) is, if the mass of our Sun is M, abou0ukkt(v1 )i2rueob1s t

  Supernovas are thought,z8o v91/,* jbqya h+xibr emdfu s)k: to always result in

  Black holes

  Pulsars are rapidly spn 70ch3a;kdafcofzkz9yu+ 0 (inning

State Einstein's principle ofm,g3 0c-3xatvu3ieh5g xz:h :7 q dumy equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cente m+5seok5rfh8, jp5lmzg2r l5r of a sphere within which nosze52of5pjl5g5rlk, 8 mm h+r t 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 wavelength in the visiblt8a0v3 f/kw ijn d:1dfe, and the source is moving away from us, the coloj:dnt/ k wi08 fad3v1fr of the light appears to us to be shifted toward the

  The cosmic background radiation coi::nnpp6eew.gy6 rl lke3l./rresponds to a temperature of about

  The Sun has apparent brigh/n8dcgw7o8gb +z1 wj y-rjk9r tness 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 7fu4f.79tn, tyjufinof 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 radius nf0pd)vtpl4 sn 4d:t 55k n7yoof $1.5 \times 10^{8} \; km$. 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 of 3ui5kf a 15pi +2tffbl/e a6ny$1.5 \times 10^{8} \; km$. 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 f*83d1dr i qln cgr6o).l fl1aior Proxima Centauri, which is Earth's nearest star at 4.3 ly?drlldf).61 g8* iiqo1 3anl cr

  The apparent brightness of a hpj9kv tw(w9z zqn3q62 .3r ncstar 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 that83:m zb-tnk5+mjrvkqhky1 (x the approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly:5bhx z k-kj kqm+(vt31mry8 n, estimate the age of the universe, in years.

  If a galaxy is moving away from us at f*m1f pq/mu5h1i/smu 1.0% of the speed of light, how far away is it fru /h im/ffqm*p511s muom us?

  Estimate the speed of a gj/xu ebp,;:f ualaxy that is 10 billion light-years away.

  Estimate the observed wavelength for f7 .can )6 :pu2r1f0 6+ekonudn aubjuthe 656 nm line in the spectrum of a star which is 100 million light-years f abf 6e:0rua7nudfk1n n+2 pou6.ujc)rom us.

  About 1 ms after the Big Bang, the temperature of thzohvn4rn 6.zur 6h)* le universe was about 1013 K. W v*nlr)6uozznh 6h. 4rhat energy (in eV) does this correspond to?