The appearance of the great range of brightness among stars is due to .td2p fxi/gg3

  The absolute luminosity for most stars depends on thmfb95 ;7s u0coh-h2 4zz8d( wqglrtr7 xq;eele

  Four different main-sequence stars are colored blue, orange, red, agx /jg ;( bgs6q r77x5eg8aiymnd yellow. What is tgrg( sx7 7m;g a/gx6y85je biqheir rank from coolest to hottest?

  A Hertzsprung-Russelll l :hlmf-bx407h .apf diagram shows stars on a plot of

  A white dwarf star with a mass equ.9l21 rer8xdom q*byzal to that of the Sun is about the size of

  The Chandrasekhar limit of .* e 5qq.z(z7hcxsn ggstellar mass (below which a star will collapse into a white s qzcqn*x..hgz e7g(5 dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to a xno4;cfzu4 e 7i(j/x zq tlv-:d9j3uylways result in

  Black holes

  Pulsars are rapidly 7)*,hwhkcc iv0y/ jcm spinning

State Einstein's principle of equ+sv2r6ozo9 z f;:hj mhivalence.

  The Schwarzschild radius of a black hole is that radial distance fromjnr3ie7 9j,z* +k rbqv the center of a sphere within which not even light can escape. It was first discovered mathematically by Sckj7i *,zvrr jne 9b+3qhwarzschild 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 wavelength in the visible, 74hqn*h:qo(7mcy a8 hrwrvb:and the source is moving away from us, the color of the light appears tmc:n4b7(hhqr8y*:qroah 7 w vo us to be shifted toward the

  The cosmic background radiation cora u d.k+ 20c3xqrvk:hpresponds to a temperature of about

  The Sun has apparent brightness at Earth (gwp e 4w;zg75d$1.5 \times 10^{8} \; km$ 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 thbyk1 ilre s+.8+/ubd qe 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 mea9jr6qus3gys ;kndv kq4j bupn j:( c6;fm2s/9n 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 radius (fihyl g)y9q6 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 Centax5 bqdqzjs q77w zl/;,uri, which is Earth's nearest star at 4q7j xlw qz5z7s/,b ;dq.3 ly?

  The apparent brightness ofp ;fj,tx),(4e odjf7+k ce zom 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 approximate age of thqy94 ojr a9,mre universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate th yo9rm9 ,j4qrae age of the universe, in years.

  If a galaxy is moving away from ut)gy n5 trqjrryqh8k.l0k 3)w rt3 6fa*wq f21s at 1.0% of the speed of light, how far away is it frlwwg k)qqh5qa13 y n 6.jtkf32r)r ttryr8*0fom us?

  Estimate the speed of a galaxy that is 10 bilu o /y9/tialp-lion light-years away.

  Estimate the observed wavelength for the 656 njj.nt v2tc1i 6 6ulm-mm line in the spectrum of a star which is 101 lit266 -mmu.ncjtjv0 million light-years from us.

  About 1 ms after the Bmkyvweg2 -ujv)7o o 66se b;r,ig Bang, the temperature of the universe was about 1013 K. What energy (iw),6v ee;-mjb7oy6 us2 gor vkn eV) does this correspond to?