The appearance of the grkf,esmsq x+rg. ;5f q6eat range of brightness among stars is due to

  The absolute luminosity for most stars depd* - lbh-ef sq.yiy1ve:c,vr( ends on the

  Four different main-sequence stars are coloredvj-nl4lspd p.s ge ,(2 blue, orange, red, and yellow. What islvpjed4s. 2p,(lgn s- their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars o o;s2zfw1.a wwn a plot of

  A white dwarf star with a mass equ /h+ gk/mvvo83x8 u54d,czb)fftphqd al to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse intbf:cu:6b:mgv wmv *w / eart/4o a white dwarf) is, if the tbm/6m 4a*wvu/b:fe ::rgwcv mass of our Sun is M, about

  Supernovas are thought to alwaysj4kk2k f8;kne )eq ce: result in

  Black holes

  Pulsars are rapidly spinnina1g;azt;i mm 2 c/wyd5g

State Einstein's principle of equivalence.,a*t*9vjtg)a1m0sc p v t+ i5vnrqq p*

  The Schwarzschild radius of a black hole is that rad68b ihniw1:-pu6i fxk ial distance from the center of a sphere within which not even light can escape. It was fi n8-pifhw6k6 uii x1:brst 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 particular wave5rpb2b x6ab4o1 sk0y1q y)fawlength in the visible, and the source is moving away from us, the color of the light appears toys 6xabq f4r 1kb0 oyba5)12pw us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of()tj iko4uuj. bm q 7(l3m3ryu about

  The Sun has apparent brightness at Earth x/:bpocf3yg+nzsq slgok7 2k6 28f2 w($1.5 \times 10^{8} \; km$ 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 o bk2z 96alt 3lku*wej(f 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 radius2j+l s2 bs m2)b duy+x5gxbj5n 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 radiuswc*a 4 mllol.ph 14rz311j yeu 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, whpzn,- yw zt, (-ffhyk.ich is Earth's nearest star at 4zf,ny-- kht,pfywz (..3 ly?

  The apparent brightness of a star; hymw3x+d an2ff;5nx7 x4ts j 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 appu6o40*x; ;ukatp+tb dn/v/b wmk z(ub roximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, intb/tnu(;buzkx u0p*vwk 6 ;b4 /dam+o years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far k.bst )v e lw7z* yq1o zco9y1m;,wsy-away is it from us,zssv oyko m);17wl19wqe-yb*yzc .t?

  Estimate the speed of- (f6ldsfkz ;u a galaxy that is 10 billion light-years away.

  Estimate the observed z6gnxlb* :;.kt2 o 9jgjhta3q clqw -hf)e91fwavelength for the 656 nm line in the spectrum of a star which is 100 milli96-:3 qj)etzc hbjh 2 *f;qk1nlt9a.wggxo flon light-years from us.

  About 1 ms after the Big Bang, the temperature of the universeu*peg/we9o/is . 52hvuz k 6v.-b ylqu was about 1013 K. What ene/ uzh /lwispy *.-q5uev kbovu692g.ergy (in eV) does this correspond to?