The appearance of the great range of/w3bv2hiubfk 8sz ol (xr7p7 : brightness among stars is due to

  The absolute luminosity for most stars ihl4 s8y(d7am depends on the

  Four different main-sequence stars are color59aixq9 slf0cmka p )w54s ske26asi*ed blue, orange, red, and yellow. What is their rank fro9*x0pcikm2f4sisaa)9w a5sk sqle 56m coolest to hottest?

  A Hertzsprung-Russell diagram showsg(b frx sm.,.a7 tc qt/lv+yd0 stars on a plot of

  A white dwarf star with a mas23b* 8iz(3uqgv uzyu vuzi* +4ynw2s cs equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below whi*l1pg, gr;loahz-zw .*oyrv/ch a star will collapse into a white dwazyzg pl;1* *rvgar l./how o-,rf) is, if the mass of our Sun is M, about

  Supernovas are thougtxp ou2x:7mk 9ht to always result in

  Black holes

  Pulsars are rapidly spincz 5 dr g3na n6znkeqefvl9(f3)9b2 +oning

State Einstein's principle e .n0hov7 ojk8k6z* jsof equivalence.

  The Schwarzschild radius of a black hole is that radivu )qt* jzzplcvh(x()r3 uc5mxg /n84al 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 beqjv*r5zzg)c/) 4nlh(tu u3xx(pmv8 c 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 emjwrcni,tk uf1mt 1 f,a,k3 6d8its light of a particular wavelength in the visible, and the source is moving away from us, the color of the lighcj1 tfr,twka6,d8nif 3,1 ukm t appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of aa1mrc;2c0 j:a our*1palxn g3 bout

  The Sun has apparent brightn+ih(2l2 wn rbyess 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 (fn:n8 wfku,kc mz1m6 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 mepu* 8 vu4;; uk1rz 7tdm,*xzkpf5rkahan 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 ofve- lgvh59u9k $1.5 \times 10^{8} \; km$. 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 u 4j)n 7k9p15ek +tficjsoi)x angle for Proxima Centauri, which is Earth's nearest star at 4.3jp7 )ufk+4 9xo cnk1s5 )iteij ly?

  The apparent brightness of a star isnlmqml3 y)r oho +k)+3 $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age ofa* lv/2a:u w54y;bu j 4ufevxk the universe is 1/H, where H is the Hubjyf 5w*/ 2a4uuxbea4:l;vvk uble constant. Taking H = 20 km/s/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 away5g nz, gfn, hu8ly(i eybccei + gx14t7/y/,lx is it from8 y+g hnyci7e i l,e (glnyb1u,cxf,5g//txz4 us?

  Estimate the speed of a galaxy wd ( z1 :fbod3yl i9j:-b s.hxd7k8rgnthat is 10 billion light-years away.

  Estimate the observed wavelength for the 65ct9baqvb s-/76 nm line in the spectrum of a star which iscasq - /bt7bv9 100 million light-years from us.

  About 1 ms after the Big Bang, the temperatubl1 fr3t+b1ns 99d caere of the universe was about 1013 K. What energy (in db1r93af1le ct sb9+n eV) does this correspond to?