The appearance of the great range of brightness among stahpy4i; / pubt2rs is due to

  The absolute luminosity for most stars depends vz 9;zye*iin1 on the

  Four different main-sequence stars are colored blue, orangel :usn);o0f hshl8l1 a, red, and yellow. What is their rank from coolest to hottes8ha l10sfl;nuos )hl:t?

  A Hertzsprung-Russell diagram shows st*)zt,*lg50qearcv nzh,b surq/9ry3 ars on a plot of

  A white dwarf star with a mass equal to that of the Sun is avn 0 chbtf-gin6y,2mj9(z ( 4h(za pqgbout the size of

  The Chandrasekhar limit of stellar mass (below which a star will colla7s 7ppy 5z)nou m qmxm-,1db+tpse into a white dwarf) is, if the mass of our Sun is M, amdup1pq 7b)-,txynsz+m om 75bout

  Supernovas are thought to always r)6zr );kxv x xftnfw+-esult in

  Black holes

  Pulsars are rapidly swj ,/38j npgt4l7rexjpinning

State Einstein's princm)z;y(detja h qtb(d;: gi 7.wiple of equivalence.

  The Schwarzschild radius of a black holez/lnwc pj4hl0j0qg 0 :t mzb r6m2i)z2 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 Einsteim:zq42mh 2z rjji0 b00ctl /) zpn6gwln 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 exd,j.z(z mv) 3nglmfbwp *3vp0:my;p/h y*mfmits light of a particular wavelength in the visible, and the source is moving away from uyzmmm0fw3dp.p : ,*zl vv mh;pb/yjxn3fg)*(s, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of y1 5a):x1mstf)zuqve3o2* f ns kpg 4babout

  The Sun has apparent brightness (z8z04 wx,o+e+q bom m2troyrat 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 toqwm2ud7 kds - . 8wxi4ts+hiv1 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 haczf*;93gcrg m 4dfr q1s a 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 o;4qd p /*zgm+nb-4nof59rkqjg8 oe za 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 angle9 zi/:t)d/zzg*j ou)zbgeu uu xuh8(1 for Proxima Centauri, which is Earth's nearest star a u :8ouuth*ix/z /)ggbed(z)j 9u1uzzt 4.3 ly?

  The apparent brightness of a star is 0vvy43mw 1 m lu4yk 5goju h6pvn3hn/;$1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universe is 1/H, where H is v*, q*n7f 29/ezf 1hiorc brbzthe Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, r hz/v7fi*qrf*bb21c neoz 9,in years.

  If a galaxy is moving away from us at 1.0% of the spha rs j.)jh r*5hn02: t3hztafeed of light, how far away is it froa :5z*j3f0jr2 hsh)hnh.tartm us?

  Estimate the speed of a galaxy that is 10 billm4*q;vw3m*w s eps/kf ion light-years away.

  Estimate the observed wavps1zq3 1qiw e0m 2pn;zo:fc 5jelength for the 656 nm line in the spectrum of a star which is 100 million 2oi130z1cs5z;w ppe: j mqfnqlight-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 qw0 pmfx7 c:3g*+gt vbK. What energy (v0m*gp +7xg: w3ft cbqin eV) does this correspond to?