The appearance of the great range of brightness among sta)u+t 9 a9y(e ty)vn+.kksfwl jrs is due to

  The absolute luminosity for most stars depends on theehxns 7bj c4bcw*3l;(o28l rt

  Four different main-sef is pe36yx/, 6a)j1sfht3jf tquence stars are colored blue, orange, red, and yellow. What is theirjh66y ,ssej 1apf33 xtf )if/t rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows s7g3jk j *rp.l.vrhmw4h5t* the27anqtars on a plot of

  A white dwarf star with a mass equal toj1h y-4df.kl z that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will coll/+gu hv6i1h jhp1mv1 wapse into a white dwarf) is, if the mass of our Sun is M, abvpig+wm1h 1/ uh1 6vhjout

  Supernovas are thought tof;iottx)c; n9r 2 lnk4q7f4 ym always result in

  Black holes

  Pulsars are rapidly spinniw:.x(k 5ni yhbng

State Einstein's principle of equivalencerl-xb t*9/c rvh 8s3er.

  The Schwarzschild radius of a black hole is that radial diswsa he*(g7x7stance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwa e as(7hs7w*xgrzschild 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 wavel 63fkwu xmp;9yength in the visible, and the source is moving away from us, the color of the light appears to us to beuf; 9kym6wp3x shifted toward the

  The cosmic background radiation corresponds to a /68si cvlc2q x,nvz (ltemperature of about

  The Sun has apparent brightn2r mh*go/ 9jy blfk(,ress 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 equal to that of the q)f (ktz)ya: j1 k 5qjgo;deg8ggm80bSun ($1.5 \times 10^{8} \; km$ 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 hasu ()te ygefk371 .hnkv9ylle. 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 km?

  The Earth's orbit has 7 boq:xp0. emua 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 for Proxima Centauri, which is Earth's nearestvelyxd+( dok24jq0 58 xe( jeb star at 4.3 ld(e d 5bjle oy+(4eqxkx02j8vy?

  The apparent brightness otdqq ;(lcwi 0)+t l7 ta/damt z,y,we*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 the approximate age of the universe is 1/H, where H is the mwf05ctz .h okh d +gj2-)1bwmHubble constant. Taking H = 20 km/s/Mly.dtmf jhko+ 12bc5w- )0hmwzg, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% o 5*yjbdoa 8paf8ix j-3f the speed of light, how far away is it fromf-a8 j*5x oy3aib jdp8 us?

  Estimate the speed of akx(8llw n,joc2 do+i . galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star hrg,w/k: wnmue li;j9: f1r-gwhich is 100 l -w9:uhgw /1;kfg j,rr e:nimmillion light-years from us.

  About 1 ms after the Big Bang, the temperaturdar t7km +/4ejt 0bvl7e of the universe was about 1013 K. What energy (in eV) does this correspov/4tael d+rk77jmtb 0nd to?