The appearance of the great rf4-(pzq wl1j xange of brightness among stars is due to

  The absolute luminosity for most stars de)i v x3ilbkv,, 7 wx1,go/qfyopends on the

  Four different main-sequence stars are colored blue, orange, red, and yellob7a)0qy3xeudj / z v8gw. What is their rank from coolest to qyxj7uz)av308e d/g bhottest?

  A Hertzsprung-Russell diagram shows stars on a 1hkan2wa2qnj rk2 3c4 ady9b*plot of

  A white dwarf star with a mass equal to that of the Sun is abglnxh.w5gd.g 7) :r hvout the size of

  The Chandrasekhar limit of stellar mag- kh3 p(jqwv*ss (below which a star will collapse into a white dwarf) is, if tjhqw*p v3k(- ghe mass of our Sun is M, about

  Supernovas are thought to always resulc sm. 6spl. ,av9qib.lt in

  Black holes

  Pulsars are rapidly spino4pvi/kro.oox 89/.a w2+h nxm/mln fning

State Einstein's principle of equivalenc 9x +tpnwu2w rwq8l/m0e.

  The Schwarzschild radius of a bla) fzsx- yv8i:gg/*s;94 e fimkbr fj0sck hole 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 from a star's masb4) 8g si-f my :z9sgfreksfi;/ *x0vjs 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 visiblegg) s; ku yz4kg7+ )vw:garzug( e+/yl, and the source ;ge (gzzyy4svg/ g):r)wklgu ++k ua7is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temw8( wu2y*xz ugperature of about

  The Sun has apparent brightness at 0,)gpvkolbr su g6/y 1/6ebfbEarth ($1.5 \times 10^{8} \; km$ 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 equaft*7xm/ ) toial 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 meanchlit9u+c,;2g4 ip n o 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 radius o*c6,o it8+nz qr+ v.4ofkwvxl f $1.5 \times 10^{8} \; km$. 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 ismf- 2yxede;) yyg 6*i+clb v3w Earth's nearest star at 4.3bly-+*y v ;gyfm)ied62cxw e3 ly?

  The apparent brightness)s(djz u s9g4w 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 r( ch8typ)z)nis the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.hcn( r)t8yz)p

  If a galaxy is moving away fr00gftkdb rf 7(uc,m *wom us at 1.0% of the speed of light, how far away is it from us?b ufrc m(f7dt,0* kwg0

  Estimate the speed of a galax.m5e/q nxgsx004gdldx,j, ta y that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the sr9t;eu ;nc:j o8vwz*:6nvwbo pectrum of a star which is 100 millionon juzn9e*8owv:;:w 6t rv;bc light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about +air n4wcld4, 1013 K. What e4d+n,air 4clwnergy (in eV) does this correspond to?