The appearance of the great rangejugr7q(8xw 4dymd 4q3 of brightness among stars is due to

  The absolute luminos6mu socu b5y,,f- m lemz8h)p,wv.. mvity for most stars depends on the

  Four different main-sequence stars ajfb,2k*ifp6 1aeo8on re colored blue, orange, red, and yellow. What is their rank from coolest npa *1foofje k,26i 8bto hottest?

  A Hertzsprung-Russell dafz x ;d) b3ugjd97hg3iagram shows stars on a plot of

  A white dwarf star with a mass equal to thats+6 rse,+kta4))j svlh mps.b of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collaps5a /,2rbjqyivj5lo ya4u 3u7y)8d rl ge into a white dwarf) is, if)goau dav,uq8j 74y j/yylr 53ir2l5b the mass of our Sun is M, about

  Supernovas are thought to always result 9bw)vml j kgcj;v+*6ain

  Black holes

  Pulsars are rapidly sp5rsr.,uzuz9 q,g kd070w bv vtjqsh,0inning

State Einstein's principleaj;zb48 vli,r /-8 60vrny:rpgdumvr of equivalence.

  The Schwarzschild radius of a blakp.9v k(59fdhc4e yavck hole is 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 relativity theory. It can be calculated from a 9kfhapk(dy9v e45v .c 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 visible, and s*+ 5 p eqkb5m1ph+x(1xxodsn the so q*sk1dx51 hxo5+mxpbse+(np urce is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of ab.fcmkmxh3 tb:d1 *j 7oout

  The Sun has apparent br mok+lbrd:9 q,ightness 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 equxoz; .8/*xrf.bbzgsf -acv )kal 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 lon) g6xj5k6hl4gh jh+2,glla 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 r)jtm e( 8v6h spg0u1hhadius 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 Centauri8 q8iiampv25 2w-fpnd, which is Earth's nearest star a2v- f8i5p2i andw8qp mt 4.3 ly?

  The apparent brightness of a star itacpw, x:k b/6v tqdo+8ltd41s $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximat)x40df)xiwn36 30ep)euq z;lv ouqiie age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, es)u3xzpo eu fi)4;iwln30qx e )i0 6vqdtimate the age of the universe, in years.

  If a galaxy is moving away f i 2*z5od-v7 zh1pxpbx;lhnx*rom us at 1.0% of the speed of light, how far away is it from us?pn-zo*hzxh5 1vp ;xd2b7lx i*

  Estimate the speed of a galaxy that is 1;ae/p k78m:c e ndda+x6:zyjh 0 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the z q odid5)h7kz44l 8wi.lnuc v9ww, m-spectrum of a star which is 100 millnc4wdhwzi9 z7 ulqo8- kv. d4m)5,iw lion light-years from us.

  About 1 ms after the Big Bang, the temperaturcr3fe gor d.i(1qo/t,.:j;q mwevc(j e of the universe was about 1013 K. What energy (in eV) does this .(cvq:1r.fidc (jemqje;t, r wo3 go/correspond to?