The appearance of th+hg3 fzx ljl2e h21/bdj)tob(e great range of brightness among stars is due to

  The absolute luminosity for most sv q2ee7/h :nfiz.mi;x tars depends on the

  Four different main-sequence stars are colored bluep2fk;h/*t 9sil y3j pc, orange, red, and yellow. What is their rank from coolest to9t/sc* p2hky i3f ;lpj hottest?

  A Hertzsprung-Russell diagram ,d, z gb(r64 rpbdxc)gshows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the sizep, +owt)tk(gh of

  The Chandrasekhar limit of so2 j2u(3azpvf1 ka,x htellar mass (below which a star will collapse into a wha hk(o,uv21x2fp 3j azite dwarf) is, if the mass of our Sun is M, about

  Supernovas are thoughm,ngo,3-m fu gt to always result in

  Black holes

  Pulsars are rapidly spc;h64jd;z rmqu9 aq0m 0cudn(inning

State Einstein's principle of equiv5yjhwhp /5.4h f)gbtn alence.

  The Schwarzschild radius of a black hole is that radiayvl (po ,sb3 (wraqj/)l distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild (bos)rvjl q3(wap y,/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 wavelength in the visibleodeek7(a/n. 9,kfqh 1,cj9. t gtm,elw:x zca, and the source is moving away from us, the color of the light appe(g9 wmtle /ke,h a ,.edxn9fo7j c.:q1z,kt caars to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature o/3vm+utg9xs* p ep pq3f about

  The Sun has apparent bri 9r1bvob+;u xbghtness 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;u bf7l43 -lwgh9 fpg31;)duh( mdgc fpjrg1r 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 a4es6 /pijj1 rv9/ooit 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 meanad .ot+ *b:lmxi zb7z0 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 angl0 3ch49hwed/ hro k89tk gn/yje for Proxima Centauri, which is Earth's nearest star at 4.3 ly3d8ecrhohy4jk /t/9g0w k h9 n?

  The apparent brightness of ml:bl +-5mixiy r*xn y+qm 7v0a 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 qcrh5q p+5ldm 7tha 3*)jmcsfmg) kx +w0ci: 7is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the unhxmmc+ 7*tds k:)5 fw3ga 5+)l0riqpqhmc cj7iverse, in years.

  If a galaxy is moving away from us at .4 fg (sj/m4c53cnz hxp 9 1yk8mvk sg/thak.r1.0% of the speed of light, how far away is83 v c gs/1khang/k4 49sh5tky.x( cm.rfjzmp it from us?

  Estimate the speed of zgi3c8v+ w6+ wyyo7:z2xflcwa galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for j i(aqi;;m.2ca g 8amf*kt-ptthe 656 nm line in the spectrum of a star which is 100 million light-years from us.jimgt maa*atc- .i(2p; qk;8 f

  About 1 ms after the Big Bang, the temperature of the universe q1nq7q/nlx+ l was about 1013 K. What energnqln+ /1qqx7ly (in eV) does this correspond to?