The appearance of thysz*55b; +y,gtqlrkh8s bvf 0 e great range of brightness among stars is due to

  The absolute luminosity fod 6 neg,8/4dvqj, tefnr most stars depends on the

  Four different main-se g6c0ya -iz;yxquence stars are colored blue, orange, red, and yellow. What is their rangx ay6-i z;y0ck from coolest to hottest?

  A Hertzsprung-Russell diagram shows starsxzswb*.0mk.s o xbx; awt 3a*8 on a plot of

  A white dwarf star withp (ib0m 0wxgutilu +gv,( ) ri/(m*inx a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar masscy( n64;r6p-es 5(oxlev wpe h8;muac (below which a star will collapse into a white dwarf) is, if the mass of our 4lu npay 6 csx p;8r(56whm;oeee-c(vSun is M, about

  Supernovas are thought n+5gw kt9/k.hzufw;k to always result in

  Black holes

  Pulsars are rapidly spinni*zl pm*ko 1o*ing

State Einstein's principle of equival+h gejtmbwk68wl2ha 4 27i/ewence.

  The Schwarzschild radius of a black hole io ci nh; ua.zp17-jk8os that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Sk7oh n8caoi;- u 1.jzpchwarzschild 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 wavel510/dqzans i fength in the visible, and the source is moving away from us, thns/f0qz1aid 5 e color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds1/ os 2wit+.xsyf)km w to a temperature of about

  The Sun has apparent hun dm,2 rhuuz+enh*l7.*v7 obrightness 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 lumiz ckcs8oi :3w,;d/hcvnosity 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 meaipdyyud(- 1(hh4vqu7 n 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 radiuy sopqlczd,mpqw+:z,s,8iz6h1 ( .ors 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(epsqextlw qufa f:4 9:v1q tlb ;(/5z Centauri, which is Earth's nearest star at 4.3 w1 q pfl95vqt:ublq t(sf:4/zxa;e( ely?

  The apparent brightness of a star hze/e))fv2w-da+0zx w3k ca ois $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the univ uq;:1pluph*7 enl4uk erse is 1/H, where H is the Hubble constant. Taking H = 20 km/s :n ql71* uu4pk;lehup/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, how far away ef81os-s0sfzk ol 4u0p9 wfr7is 8fu 0l- o1so4pfek0fs zrw s97it from us?

  Estimate the speed of a galaxy tha3- )w/+hwtv)j hsj x )stpcp4wt is 10 billion light-years away.

  Estimate the observed wavelengthq(l2s1 ,b ls :zxf0sikox3d 0m for the 656 nm line in the spectrum of a star which is 100 millq0,k0 lfxs1:dbl2xo 3z(ms ision light-years from us.

  About 1 ms after the Big Bang, the temperature of the t)iu atn89o a0wxm 7)quniverse was about 1013 K. What energy (in eV) doo)an8 90ttxamu7i )qwes this correspond to?