The appearance of the great rany,ctr v, 5wpe:ge of brightness among stars is due to

  The absolute luminosity for most st6hai/rw cx (sv*7 r/ tk7ou7ytars depends on the

  Four different main-sequence stars are colored blue, orange, red,tsw o h-jw-t02o95hvgno d4l) and yellow. What is their rank from coolest to hottest?2o0)-sw9v lo-ogt45dwhtn h j

  A Hertzsprung-Russell diag t:me4qpk9a v0qy 432uh1z bkwram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is abour5t0tlz a- .zgt the size of

  The Chandrasekhar limibg,3ammsx d* ei : brsp*b*z:3t of stellar mass (below which a star will collapse into a white dwarf) is, if thb,zs3x*s r dmim3*b :ge:*p abe mass of our Sun is M, about

  Supernovas are thought to always re:w(ai 0fyo.(srqnn3ek+o yd qa( hj3 +sult in

  Black holes

  Pulsars are rapidly spinnzs : + ebha8pv0e r5x..adl9/lrhvs g9ing

State Einstein's principle of nbd: vo4u+j 57d.d.yc revy* oequivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cente5e4,a b,(bi*sjoy0g,gtlhxh7( w mgur of a sphere within which not even light can escape. It was first discovejexthl gm bs0o(iby,g(,7*wga, h5 u4red mathematically 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 particula;lo kg+ymfd:f5j .0fv r wavelength in the visible, and the source is ;d.fy5l m f0v+k:gojfmoving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a tempere nvx 6q)9-zfc(hq 7hpature of about

  The Sun has apparent brightness lmf ;)id3.sc2q e mtq*mr:l6xvz87g dat 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 q). m+lgu lxu1j v6lnqff+9h9to 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 abyo hk 6j,p(tct- 1i/m 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 has a mean ra4bei /ww q5)yndius 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 neabgtl44 mt9y v6nf/i4afzzb* *rest star anb6y9tlf4m* /fg4zv4 ti* zba t 4.3 ly?

  The apparent brightness of a defdyxj8tu mlk7g)/i;u70 a;uy a v3 7star 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 uni 7tlisu a(skloi*q-ljr+i,,* verse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Ml-,7usi*qs+ (atr * kjiliol,ly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how fz y-xtj;b by1obx476k ar away is it from us?6j;74 zbbkoyb-yt x1x

  Estimate the speed of a galaxy that is 10 billion light-years awauv9o3 w*099p /h3zayj taviey y.

  Estimate the observed 719gdmmlir3nz/i 5tb555 hekoc w 4hnwavelength for the 656 nm line in the spectrum of a star which is 100 million light-yeahi9lckm ndgo3mt/h715w5 r z4 55 benirs from us.

  About 1 ms after the Big Bang2l vsj* :lmog6o( hcya;nodu*5sx5;p , the temperature of the universe was about 1013 K. What energy ;d mp;gvy a (hol52csu**lnj5:6xoso(in eV) does this correspond to?