The appearance of the great range of brightness among 3jpidt-nu walo +tiid66 :/a,xrpm4. stars is due to

  The absolute luminosity for most ;*-) j0bks-o6cef+goad (wx z brdc4 gstars depends on the

  Four different main-sequence36mhbysy8 ct1i: 1 ozy stars are colored blue, orange, red, and yellow. What is t 6oc 1yzy 3y:s81bhmtiheir rank from coolest to hottest?

  A Hertzsprung-Russell+ypxq*b(q xc 89c,: s94uh gp jm5o4p 4dhtceq diagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is abouh .(syvvm n7yb-1ebndga )a7-t the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse intoi +5aat0twr )c a white dwarf) is, if the mass of our Sun is M,i+ w)tatca50r about

  Supernovas are thought t qf qvb j..+uyhz6xz7r 85utw:o always result in

  Black holes

  Pulsars are rapidly sbsb9d /mwr, 796z74jjh d tw* fgktzy9pinning

State Einstein's principle of equ-b k8 u; 0c:ryykgegh)ivalence.

  The Schwarzschild radius of a black hole is that rad(jlnt9tq rt4 1ial 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 c9ttrt4n l 1q(jalculated 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 r8tbbaj* kaks*, (0)jq tsm7la particular wavelength in the visible, and the source is moving away from us, th t*sm,jqkbka)*ars0l 8btj7 ( e color of the light appears to us to be shifted toward the

  The cosmic background radiation corryqq31 7pq1ler/9vhg 8pji 9e 0gt i/iyesponds to a temperature of about

  The Sun has apparent tf4:u x*sbqcvqf8d / u(g8dk/brightness 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 to that of tp ** gca4b-shfog6 gq9he 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 radius ofdo e02guf rf*;,a0j9c6wwr v f $1.5 \times 10^{8} \; km$. 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 fglm0/be)e zb 8 .vu9ea 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which8kxbqhi ,h 97:v mae(h is Earth's nearest star at x(h h8q79k, :vamhbei4.3 ly?

  The apparent brightnep15 hmcp8lw g1ss 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 th.6g wm-+aqa 8yblzts m)8s5ype approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the a6+8l5bmy- yw aqtzm .)gsps 8age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, hcpa4z0wtxt u8 .qr9 )yow far away is itt8rywc u4x0 .qa9p) tz from us?

  Estimate the speed of a galaxy that is 10 jtkmq p0 ,fn22billion light-years away.

  Estimate the observed wavelength for the 656 nm line 2ilw +7ke1xhqin the spectrum of a star which is 100 million light-years fromeiql271hx + wk us.

  About 1 ms after the Bgxac4(7y3te5 w f2m fhig Bang, the temperature of the universe was about 1013 K. Whhwmf 5x yf2 47a(get3cat energy (in eV) does this correspond to?