The appearance of the great range of brightness among stars 4 )pa8 26cv(pbjw xl bargk lyx7xls0:4of/7nis due to

  The absolute luminosity for most stars depe /i 4:0pnvr:gykap7mrczg;1dnds on the

  Four different main-sequence stars are colored blue, orange, rei3sy 9*lzir2y22 cthi-*qived, and yellow. What is thv i9it*2qz- h r3yc2sel2yi* ieir rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a vx(fnz*i rs .vu3r pf0ts: .)kiw1f*9 ubsru4plot of

  A white dwarf star with a mass equal to that of the Sun is abolf(7 )2 07cz m bk*pefmc ok9jws+2ujkut the size of

  The Chandrasekhar limit of stellar mass (below which w+k(yk lyp w+pco -5g.a star will collapse into a white dwarf) is, if the mass of our Sun ispp+wky-k+ w(l5gc oy. M, about

  Supernovas are thought to always re. waftqmq zs+dfyg-u -m0*5:gsult in

  Black holes

  Pulsars are rapidly spinningmwh29z au 9vryb379c je, /kib9hfhf,

State Einstein's princ1n)ltmmql) -/zk/w43jnh u da iple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the c, hi- +q,zbpgo9loo e8 aj,tt8enter of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein publisp ateoozg+8i,h-jtb,l 8,qo9hed 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 wavovn z g* (cw9hur;pks+y 8i.5eelength in the visible, and the source is moving izowr8u +sgy5v k .*n;(c9pehaway from us, the color of the light appears to us to be shifted toward the

  The cosmic background radia2nul fu+t sqs,ki:-q -tion corresponds to a temperature of about

  The Sun has apparent brightness at Eatzwtx,hn*7f ; rth ($1.5 \times 10^{8} \; km$ 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 lumi22 osj/c (9hptmf4 dcrnosity 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 mean radf5 qvptll-4v*zc62+zo +qt/ske 8 y xmius 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 radiu cu)pnyg ;.,tks 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 nearestp .um)y3xip4l star at 4.3 l3xuyl ).m p4piy?

  The apparent brightness of xr) lzcc/u8w,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 theowr xf+m(.3rs4e 3xqz Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the u 4xew(+m.f xror3z3q sniverse, in years.

  If a galaxy is moving away from us at 1.0% of the speei .j kvwp66)/9 bg7da()j nvhvjjy 5tdd of light, how far away is it from usv6 giapdntwv5 b(yj))6kjd/ 79 h.j jv?

  Estimate the speed of a galaxy that is 10 billion light-yea ffp(tlr0ei6 v gnlb-m(px:6 9rs away.

  Estimate the observed wavelength for the 656 nm ct1uo+wdd,mgb3og9 tk t-ayq 38p l9) line in the spectrum of a star which is 100 million light-years from)8uad3q plty9,wotg+t1mg od k3-c b9 us.

  About 1 ms after the Big Bang, the temperature of the universe was wpkw*s 8soc08 about 1013 K. What energy (in 8*psoc8w ksw0eV) does this correspond to?