The appearance of the great range of br:bp /o.7nebfi ightness among stars is due to

  The absolute luminosity for most stars depends on , f*-zikpenvo7az4( s;wwdyt; 2umc 0 the

  Four different main-sequence stars art(5bltsaz*rr *lmi;ox8u(mu,j 9) ns e colored blue, orange, red, and yellow. What is their rank from coolest t r8)5uo9,(aismn x(jm**b;sl lruzt to hottest?

  A Hertzsprung-Russell diagram shows starr2pzg-9mm-htb+kd k-2u l:ibs on a plot of

  A white dwarf star with a mass equal to thatzdh(9/fxv2y f of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse izxnu262c+ za vbknu02 nto a white dwar cbxvzn02 k n2auz+u62f) is, if the mass of our Sun is M, about

  Supernovas are thought to always resu1sr frfq1v z;*n6zb n:lt in

  Black holes

  Pulsars are rapidly spinni2qtf10j cc-9jslcj9 hlmjp*,- g6+ zphkbx9 ung

State Einstein's princr4ot/ 4 yhl7pmmxbkj:yp 6c5)iple of equivalence.

  The Schwarzschild radifay/g5ot - xo9xur).sus of a black hole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically byuf. )5atx-/oygr 9o sx 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 partic+s/iwz)8s qyx q, q3saular wavelength in the visible, and the source is moving away from us, the color of the light appears t,qi sq)/wx a+y8s3qz so us to be shifted toward the

  The cosmic background radiation corresponds yh)afj63n w5ampnwiy91m97+13iylu8a guds to a temperature of about

  The Sun has apparent brightness at Earhpxwv8e 6tg0- th ($1.5 \times 10^{8} \; km$ 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 the Su z-rzlis2-lo6 n ($1.5 \times 10^{8} \; km$ 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 r 4gz(t) ledpx+adius 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 zxt .m73m(zn zn s5)rvof $1.5 \times 10^{8} \; km$. 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;ok/bp8 x-nhpiije:. d)ho,v Centauri, which is Earth's nearest star at-k;. pnheb oo:p8/jx, dviih) 4.3 ly?

  The apparent brightness pxz8s 8grd03dof 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 5x -n5 w vy-wordlwo7.approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, y5.5olwnr7 wvd -wo- xestimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far(q77 wm cmv4dr away im 7dqvrm 7(cw4s it from us?

  Estimate the speed of a galax-iw5t2cwk;qe a293qkj( u mb hqfvr64y that is 10 billion light-years away.

  Estimate the observed wavelength for the kmgq*24+pmz *hojcw: 656 nm line in the spectrum of a star which is 100 m4+h:zcj*p2 go *m qkwmillion light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was abo wvpg,ypob yk0 ihbhse9sqe .7j6:c*9y )o4 u)ut 1013 K. What energy (in eV) does this corre yjc,kwu*ps e: 7siqob0goy9.)4y )peh hbv69spond to?