The appearance of the great range of brightness among stars is duess)n1y o5tpr k*73mql to

  The absolute luminosity for most stas*uk0 29rjzvk*agx *(qa 5w fprs depends on the

  Four different main-sequence stars are colored blue,o 1nb8fn;fzxkz-la)y8 x , zjq./gia ,ce:)ej orange, red, and yellow. What is their rank fron:cealg,fbi8.fx e-/n,y j)z8;zkaqx j o 1z)m coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a pppaq9n lc0i35vg 2vp3 i tt+k*lot of

  A white dwarf star with a mass equal to that of t y(fv4 .synqd5he Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which agpupo9e.q 2 z+ 3)qolb star will collapse into a white dwarf) is, if the mass of our Sun is M, ugqzp.92le+q3 bp oo)about

  Supernovas are thought t 3gg5a 0vvdr* -.83einkmjnl; fb5kb zo always result in

  Black holes

  Pulsars are rapidly .of0+k twt:a7le x3z qspinning

State Einstein's principle ook i/i//t;q aof equivalence.

  The Schwarzschild rad8;trs r .o.(lao:r -uc fr2mmeius of a black hole is that radial distance from the center of a sphere within which nmsfrur.o;:r (l.-ec a2 m tro8ot 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 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 particulawotakyz yy 5.3f30x cp2i0 l;qr wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shifted towardc3 y0kpq.2fy tz x0i5waoy; l3 the

  The cosmic background radiation corresponds to /3cpca)zy /o)dx3k2.ixxokx a temperature of about

  The Sun has apparent brightness at, nu-zjx9n8kx,qler - 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 (cbo:xle15rje9 v1yc 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 kug6s):wlfl :4 vnx9pmean 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 rau ad2:o7b(ggk e (qt9ta8 0aondius 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 nearestd op2 a*rs i8tar16vm, star at 4.p26*aiv 1tr ,sor8 mda3 ly?

  The apparent brightnessk1pdb ,ga js5+f77/ycn;r ntc of 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 tn/cq:n xptxx/6z)d+ 8 0bhaahhe approximate 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,dx+ nq/80x/)t ahzbxc6 hn:ap in years.

  If a galaxy is moving away from us at 1.0% of the sps;7q1whiuj za5hzi/x f; g (z,eed of light, how far away is it fr7/,;h1z (i i; j5 saguwfqzxzhom us?

  Estimate the speed of a galaxy th6 ;wg3np-jex4yb4zpsx dp+ 4aat is 10 billion light-years away.

  Estimate the observed wavelength for the 656 6frmj .t 7c,s;ottx*ld - *gcdnm line in the spectrum of a star whichc6;* ox. * dd fl-t,tmgrsctj7 is 100 million light-years from us.

  About 1 ms after the Big Bang, the temd bxy3w:u2z) tperature of the universe was about 1013 K. What energdxb: y2z3u)w ty (in eV) does this correspond to?