The appearance of the great range of brightness amon:f(xn 1 g3k84rhwjfzhg stars is due to

  The absolute luminosity for 86 gki9rxn(zj uiacha2:c,j8i +rfx7most stars depends on the

  Four different main-sequence stars are colored blue, 1as 0+m e+l1s3wpmtfp-ku 9qqg uk,3 rorange, red, and yellow. What is their rank from cool, -f3mqls 3 0uq1k+9u+psw1akpg erm test to hottest?

  A Hertzsprung-Russell diagram shows stars on aocy.w-+ 9uy tq plot of

  A white dwarf star with a mass equal to that of the Sun is aboutlmmpfs ha6x-d4l*q; . the size of

  The Chandrasekhar lim oz43ie +u g4 isbj4ez5j:4l6roi9 yobit of stellar mass (below which a star will collapse into a white dwarf) is, ori63e9 b4jij 444isooye+zbg: 5l zuif the mass of our Sun is M, about

  Supernovas are thought to always rett9;(jveur05okw9 ro sult in

  Black holes

  Pulsars are rapidly spinning h pk01.o4p8n,*iw 1esaormj ;5uztqc

State Einstein's pri 0u.fhe.+69b q2k3kthboxt 2oq,fram nciple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance ftul;v mo/juh :(fh6p,h3yyr /wu( p3q7 ie7tirom the center of a sphere within which not even light can escape. It was first discovered mathematically byw3,urho3eptqhj(tif/: 6il(yy/p ;vu u h7 m7 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 visibll3p) qs8a3x7wd ti6un e, and the source is moving away from us,7 p6tlwdins)38aqx u 3 the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a kfs* )ip x;3b jx,z:citemperature of about

  The Sun has apparent brightness at 4e * tgc3irjs4Earth ($1.5 \times 10^{8} \; km$ 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 the Sugr vle3nf +bs2 3vsq5o0cp gi2*w:c+un ($1.5 \times 10^{8} \; km$ 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 meanh u,qe -jr8/bo 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 ha v0t0rhhuk4i+9 ua0a ts 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, which is Earth's nearest starj z*zp (ykhq)*+p hxr) at 4.3 ly?)zyhhr(j*qkxz *p)p +

  The apparent brightnwath o7)a.:u+. wskzgess 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 approximate age of the universe is 1/H, where H is thegy rt pe/8d.p):c1vcg qfpv95 Hubble constant. Taking H =:vc9 t y /vf 5qdeg.rpc)pg1p8 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, sz ) ,q a6j,hkigfg1sg uxw:26how far away is it f1: wsqs 6gh2k)giazg,xj6,u from us?

  Estimate the speed of a galaxy that is 10 billioi6vlc0gv/-g/gyj 4mhr 5q.vt n light-years away.

  Estimate the observed wavelength for the 656 *pyn 4 zs3uez4nm line in the spectrum of a star which 3sz4nyz u4pe*is 100 million light-years from us.

  About 1 ms after the Big Bang, the tempera,8mhdoasr wmh,am4;)hjdr f.p -h7a, ture of the universe was about 1013 K. What energy (h maa4,h ,;rs,o)dfp-7m8h adjhr . wmin eV) does this correspond to?