The appearance of the great ran ;j:18v .bsvy) qetnswge of brightness among stars is due to

  The absolute luminoskvuz1b* ;z r 9ek*qzq3ity for most stars depends on the

  Four different main-sequence stars are colored blue, orange, red, xmxg q(ofvdj9u+1x,* and yellow. What is their rankxmx+f oj9,1dvu q*(xg from coolest to hottest?

  A Hertzsprung-Russell diag2 lbw 1as 2q0zx53wjlqram shows stars on a plot of

  A white dwarf star with a mass equ7 t46xkyttj rx4zc1r*al to that of the Sun is about the size of

  The Chandrasekhar limit of stellaracs l 2n,lg6;pu2kl5- ;+dpnc9b tcc r mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun k+9lncl ,lcu2;gr a 5bt n sp2c;cp6d-is M, about

  Supernovas are thought to 3h hg)4:zrb0hv3uz qzlx2w.balways result in

  Black holes

  Pulsars are rapidly spinnxasztf o 7+pb ):7dth8ing

State Einstein's princnnp 46s lss/vqsc/(sil1 0an2 iple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance fro c cnzws(9 xbrr j-*8u4f)ot9pm 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 calculated from a star's mass M as: f (4xwror9zc u*nt)8j b- 9spc$R = 2GM/c^2$. 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 6gtu+ipc z q/+particular wavelength in the visible, and the sourzi pc6q+t gu/+ce is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation ckrts*s 0 ;.rlaorresponds to a temperature of about

  The Sun has apparent brightnes qsqui+i- dvq29ks/: ss 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 luminosityx 11w d-afsah1(/ ejnyv as)j9 equal to 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 has a mean radius.k)0,ao b /tn0efmo pe 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 hass2 bhjks4s; n-ic )cd ;9cm:lh 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which is Earth's neq0 hgx7.uoh g-arest star at 4.3 q.h-hu7o x0gg ly?

  The apparent brightness of a): h)t4mm)c 6s.j peieb;jsoc 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 the0.ifr;t8 doqu8q hzhjj24 ulh :+3c vt approximate age of the universe is 1/H, where H is the Hubble constant.th8qch4 juqo;0hl2:vzit3u fj. 8dr+ Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speedfe-y.b6x ibbl u:v8 o3 of light, how far away is it from us? o8iv .xelb6-bufy3:b

  Estimate the speed of a gahqtn9526a v*cu ( ixrglaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a55 v8dtgsts-cd elp71c 3v3mb star which is 100 million li5v 7 mdegs3d t8v1 -t3b5lspccght-years from us.

  About 1 ms after the Big Bang, the temperature of the univslrtzr 5n u0+.xqr:;r erse was about 1013 K. What energy (in eV) does this correspond tou ;r0lr rz5.qnx:rts+?