The appearance of the great range of brightness among stars is duedldyg9i 7c * 39. habswz;kj4k to

  The absolute luminosity for most fkh qxkg qt)xh76-*1k stars depends on the

  Four different main-sequence stars are colored blue, orangeqjv3c j2)0bb y, red, and yellow. What is their rank from co2y)v3bb0cjjq olest to hottest?

  A Hertzsprung-Russell diagram shows stars on a 1/wbt8. ryx;z vmh .grplot of

  A white dwarf star with a mass equal to that of the Sun is about thwzcn/1 r5te3p e size of

  The Chandrasekhar limit of stellar mass (below which a star will 3++tt45c8kxnr v0lhbxke w g08lr rr3 collapse into a white dwatrk 0k+ t+r3gc5xbv0r l rlh88nw3ex 4rf) is, if the mass of our Sun is M, about

  Supernovas are though canf -fe;0brbse: 4;yt to always result in

  Black holes

  Pulsars are rapidly /83ajjko1huj spinning

State Einstein's principle of equivaleapdwye dv 882x/ 983p fw4x7bsu;x mmdnce.

  The Schwarzschild radius of a black hole is that*2 p(4jqc(q(/pp k l w,bjbfyt radial distance from the center of a sphere within which not even light can escape. It was first bk(2 plq pb(w,qj/c*yfp(j t4 discovered mathematically by Schwarzschild 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 2 zg8g. aauxi:particular wavelength in the visible, and the sa:2.8zug iaxgource is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corre ueg,dkiv+w* -sponds to a temperature of about

  The Sun has apparent brigjslrtpxi:*bo voi-;o z 49ade*)d .s:htness 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 Sugenlte 1+u.5u uzg1:bn ($1.5 \times 10^{8} \; km$ 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 aajt:,gj9sfj4 dr d99mzn*l w( 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 mean fjb 4 8 j;r5xtddto/c6radius 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 forzz a1;p/i 2jmw Proxima Centauri, which is Earth's nearest star amz2j /1pwi;azt 4.3 ly?

  The apparent brightness jrzp rr.)+w.fof 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 app.3unx i17cvt5xe7ql eroximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the 5u3iec1qxlv xet7.n7 age of the universe, in years.

  If a galaxy is moving away from us atrm4ra. y*f ly+ 1.0% of the speed of light, how far away is it flrr +4ya.y* mfrom us?

  Estimate the speed of a galaxy that is 10 billion lighty0azu( 2l1izj-years away.

  Estimate the observed wavelength for the 6rb7fjz.49x2 thne0 4 ak u m5pxaad;g)56 nm line in the spectrum of a star which is 100 million lfgx hn2m d7ku9zra)p4 5b0x jae; a4t.ight-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about vd pgd jcovrc4.zx;(/-0a. ds1013 K. What energy (in ed/ddpr az(4c ov. -0vc;x s.gjV) does this correspond to?