The appearance of the great rauanjl-6q ,zs+ 12 6foft3t ycdnge of brightness among stars is due to

  The absolute luminosity for s,h0d + iet),0 yofr/xgfjma0most stars depends on the

  Four different main-sequence stars are colo b26fylygsw :qn1:(wfc m:l65mga5 ij red blue, orange, red, and yellow. Whai6ma 5g6(qwnc1fy52w gf:js:bl y:ml t is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows 1alz )r;tsva 47uq.oo stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is c5c2 bs1zmg1 rabout the size of

  The Chandrasekhar limit of stellar mass (be25 ivpp. yz14ucttu1 tlow which a star will collapse into a white dwarf) is iu.4y p2 1zt1tv5tcpu, if the mass of our Sun is M, about

  Supernovas are thought to alway h-o.tx((vjl rd j 3;xsk 4ls7f90rajzs result in

  Black holes

  Pulsars are rapidly 1fg90w6a a cqmizz )4jspinning

State Einstein's principlekesys, ,(rs-pt*5 onxe/o n v/2bhh, d of equivalence.

  The Schwarzschild radius of a black hole 570weuoamg a3asm 6ce 7hth ys6++( yjis that radial 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 re7e a6(yshcm0h a36+geswm +oj7y a5 utlativity 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 emitg:tdfy *7w0dzb w3yh/s light of a particular wavelength in the visible, and the source is moving aw3td y0h: gyfzdbw7w* /ay from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a tempe-l 3 4iw54xsia*vlciyrature of about

  The Sun has apparent bovg/9g.cbk4 iic f m+q2:cy (prightness 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 xg2fa 5. t 2twkct:y tes2t.wg-:v ymn1z*)p vto 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 meaqrf6;:f f ifn(y xs.2kn 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 n* /id5j4kza s1zrkr 9radius 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 nearest star a1j+0u1,3gs * qrr blm.wl z0cprsbh3n bb00+s3jl3 .q cn*,rzphusgrmrw11 lt 4.3 ly?

  The apparent brightness of a star 1-xvsrsn q-ep6 r )y)xis $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the av a1(0;p7xo2 lu(-ycp5ozkb (vmw bbkgxs+i 4pproximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the ag715gicvvowpo4a(l+- ; kks (ybuxzbp2x 0mb ( e of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speej 6+vq::ctm qhd of light, how far away is it from utv:cj6q:+ mqh s?

  Estimate the speed of ah sk2aa ;/ hxkc7vh86),it tnw galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the sp1aqfuam 6h1 bb :rxch,/yfo: bml0,auz a+ (;nectrum of a star which is 10 muf/o :n1z1 6rachf;:ba(h+bm0auq,a b,lxy 0 million light-years from us.

  About 1 ms after the Big Bang, the ttryx3qdxa3*+x6c c0 zl6)l szemperature of the universe was about 1013 K. Whqtlx6 3xc +z6*s lay3zc xr0)dat energy (in eV) does this correspond to?