The appearance of the great range of brightness among starlo .aedk o. y-z64iab4s is due to

  The absolute luminosity for most stars depends on+ 4ay6m;xhyk /sw 2 eye5)z3vm lo 2f.drxj:kw the

  Four different main-sequ7t-b9x tvhg* r4yiwz;ence stars are colored blue, orange, red, and yellow. What is their r -rx9z wt*h; 4g7ibyvtank from coolest to hottest?

  A Hertzsprung-Russell diagram show8)vt7y vl:s et*c m/lf 4p-svys stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the size of0o:l*e t,8iqhsziq3 mw5 l2g3rmfdk5

  The Chandrasekhar limit of stellar mass (below which a star will coll2tw g6tnlui+(bj;wem/ 8 cyo 01 lz1ilapse into a white dwarf) is, if the mass of our mguy2 wjt16ltzi( 8c lwo+i b/; n1e0lSun is M, about

  Supernovas are thought thstn s7li.4o1o always result in

  Black holes

  Pulsars are rapidly spiev-;8etoylxyu+;veu8ys4 ;8n(ikv xh-u2d v nning

State Einstein's principle of8akjyj:fe9zb9v;tw i h jz)ma-2f5, s equivalence.

  The Schwarzschild radius of a bl;1yy63cqe bfv ,y+ycb ack hole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered math,63;bcyyqc f+yv ye1bematically 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 wavelength8mxrl9iz vd4 8 in the visible, and the source is moving away from us, the color of the light x8v9 d rl4z8miappears to us to be shifted toward the

  The cosmic background rar4*g:okm :hlj diation corresponds to a temperature of about

  The Sun has apparent brightness at Ex h n.nyh0;dg2arth ($1.5 \times 10^{8} \; km$ 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 lumiq31ublj:is 6dx9pm x- nosity equal 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 a meuf vwwzb6hw6p1 8; 7tvjhi.r8n b xh8un2,a8man 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 has a mean rap,iz ddp r te)1id-2: u)n/krwdius 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 nea9rrom,wpk b4,e4o-x z 3aku9srest star at 4.3 lybk4mkswp, a94- 3z,eoo r9xr u?

  The apparent brightness (3+ id y1hvw;5wvywue 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 uln3d (b) +vq4zw5mv siniverse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in yea 5(4)+bd lvmqsz3vw nirs.

  If a galaxy is movinc-rhjcb ge qj1c2m50/g away from us at 1.0% of the speed of light, how far away is eg jcjr/c1mb5qhc-20 it from us?

  Estimate the speed of a galaxy that is 10lb y*cu /m bdah91w7k5 billion light-years away.

  Estimate the observed wav95xue)uteq)n elength for the 656 nm line in the spectrum of a star which isx)u 5nu) te9eq 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the univu+( -: ndaqnjbw* (g+nrnqzg1 erse was about 1013 K. What energy (in eV) does this correspond gqrb nnau:q+d*n +(n z(g1w-j to?