The appearance of the great range of brift ;7cg+jy bqp.i;i(2tz 9gerghtness among stars is due to

  The absolute luminosity for most s 4 9 g0gvwi(x19dca mg2usx.cetars depends on the

  Four different main-sequence stah0x6,.ij skf+ 1ejztprs are colored blue, orange, red, and yellow. What is their rank from cooleix, hf6sj k+p zet1j0.st to hottest?

  A Hertzsprung-Russell diags03u-ru y rg2wram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about t0z p:i49saon tnd44dm he size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse zmvdz 3/b4.1 ninq)qrsmy/ w:into a whiteb4rzqyi/ )q z.sn :wnmdm1v3/ dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always8*w-p0 m stuemse em-3 result in

  Black holes

  Pulsars are rapidly spinjkd9 zk4c ahf56+ sl+kning

State Einstein's principle of equivalenn e72b64a roaace.

  The Schwarzschild radius of a black i*.lv b g)j ,8fwnwy24 2-khwvunl7shhole is that radial 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 published his general relativity theory. It can be calculated frog )w2s7 yb nlv.fiuv kw,84l-hjhnw2*m 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 ufliq 6*zs z7 bn+(+f- )j25bfrd rjhuemits light of a particular wavelength in the visible, and the source is moving away from us, the color of the light appe sf*2 bbiq+u+z)fu(jh5l6rr z 7jf nd-ars to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature ofne0.d nq i3l:a about

  The Sun has apparent .tu:rd6u;kpt brightness 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 equaoozxlcbt2xl mysf/vr( :w-3/xf)(1 ml 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 1lk akncfcrx-ka 0./ o k/g2q u1)agb9a 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 ha*0m9h1 h 5ae6kiwww ius 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 for3 6)chv gv rpn4qg9/ry Proxima Centauri, which is Earth's nearest star at 4.3 lyq6)/ vhg9cry3r4png v ?

  The apparent brightness ouj fx2 l2zd3ic-*qbi4 f 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 thebh am.ake8 6r5 approximate age of the universe is 1/H, where H is the Hubble constant. Takinh a6km8ra.5 ebg H = 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 lightzz *q33 dbhhw4, how far away is h43*zwzb 3 qhdit from us?

  Estimate the speed of a galaxy that is 10 billion light-years)e9j cy 5v+qog away.

  Estimate the observed wavelength for the 656 nm line ivqyd 0tx9 izxck b* h8;wpe+9.x 6d4tqn the spectrum of a star which is 100 million light-years frqpth;x*8. c4 9d+z k9ve0y wbdq xixt6om us.

  About 1 ms after the Big Bang, the temperatur;4 :r7cfh)xvof(*up h0szypre of the universe was about 1013 K. What energ )(07ps:hfc*v p ohfyrux;r4zy (in eV) does this correspond to?