The appearance of the great rangej;q 2moy+hgbx* * mvn8 of brightness among stars is due to

  The absolute luminosity for most stars depea*j xq.k skt2u:q vx4-nds on the

  Four different main-sequence stars are c1ktv0y+/dm0qf3 x7hfev f xa7xz98 kmolored blue, orange, red, and yellow. What iv7/dvm 9tk0 xf e 08xz317fxaf+ khmyqs their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows se vtqa.3,v8pk tars on a plot of

  A white dwarf star with a mass equal to that o y;f/ h+vj9tynf the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will coll a d)d3 v9nml9vfzis-8apse into a whit3i-d vsv9 zmdaf8n9)le dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always r xesw8/yf/:wrb 6 i0ozobj(e*esult in

  Black holes

  Pulsars are rapidly spinn /l;ohww+3)qwhrqjuq :evj s(,7czyp2u)qz)ing

State Einstein's principle of e+:r+if s6e lvzquivalence.

  The Schwarzschild radius of a black hole is that r9b r 1nnhryc**adial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein publishh r *n91brn*yced 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 visible 0hmaxkep;h+, i saqo(-1dvm,, and the source is moving away fr0mp(e sv,hh ; +1xk- adiaqmo,om us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a bc,nv.hpse.c ,gfs*+ j-+mfr temperature of about

  The Sun has apparent brightness a 3x*sbw .68zezszocj2zp-0oft 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 of 9to145huybp t 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 radiuslz1v7 0l k9j8ttxx8s g 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 ha6-vaj p4qg4m ocu+wc.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 .xwt-1(vfdzzrq 8q4j1f:vug Centauri, which is Earth's nearest star at 4.3 lyu4fvw .qvxt- 1z : (1jrg8dfqz?

  The apparent brightness of m;dq8-iq, t +lp:qmzr:y1fk aa 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 a(lqsmqto y4,b1f r)k; pproximate age of the universe is 1/H, where H is the Hubble co b lrosk)qqm(41fty ,;nstant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us atsmrc *6z 0* yh5xdja3s 1.0% of the speed of light, how far away is it 0sxh *a*cd536y jzsmr from us?

  Estimate the speed of0o)gl;d:nj u i a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the speckr43jc;gk 2e wtrum of a star whicjgk2ker; w4 3ch is 100 million light-years from us.

  About 1 ms after the wf( uy37ael,okza.: xBig Bang, the temperature of the universe was about 1013 K. What energy (ika.f: 3wxel a,z7uyo(n eV) does this correspond to?