The appearance of the great range of brightness a xqk;:-8nn.*nwmprv jmong stars is due to

  The absolute luminosity for most stars depends kh s,g- gpl5zd,i).y xon the

  Four different main-sequence stars are colored blue, ora vvez+t5/cows8 y+jv ,nge, red, and yellow. What is their rank from coolest toov,zcw5 vtsy8+/v+ej hottest?

  A Hertzsprung-Russell diagram shows stars on a plot *t0v rmoz 4ke3of

  A white dwarf star with a mass:-/yx:zg7r8 yjo o lqs equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below whim2x9q 6v1h k;s oot4zich a star will collapse into a2s 941x6ihvt o;q kozm white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought mikn9-klf.u62o3xgz -1k;tb v0yiqh**ussh to always result in

  Black holes

  Pulsars are rapidly spinn8fy/;n:amp fz5,ir lding

State Einstein's princip/zhu/i hyk u5/le of equivalence.

  The Schwarzschild radius of a bla5ebzl6t+ u n4gc2kk, ack hole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically b,l2ketng5c u k6bza+4y 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 particular wavelen;n4a:kaj-k,(ig m;f.w: tfxho u1dw dgth in the visible, and j:ki4oma;k;1wf:n(dt fa xwg,.duh- the source is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temper :z53 u-p9yt isdmhe+e9:zdor ature of about

  The Sun has apparent brightness at Ea-s klf0 gotpm8 9ft7(ny2mn6erth ($1.5 \times 10^{8} \; km$ 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 ofs 7vlo i-*x;ak-lur j( 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 ovlut7 7yiwy*8g()alp +bhz iebypj 8b9c(; .pf $1.5 \times 10^{8} \; km$. 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 of+nx:/*i v j2ebehqy .km:vp5l $1.5 \times 10^{8} \; km$. 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 u+em(u /pkne.is Earth's nearest star at k(e.puume/+n 4.3 ly?

  The apparent brightness kot8a( g5)lb hof 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 the universe is 1/H, where Hztl7(1 5sx/* vo z6sc gzqa;rv is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, iv 67z*(qstxzs oza vcr/;1g5 ln years.

  If a galaxy is moving away from us at 1.0% of the speed of light, hbw)vj su/ kq.8ow far away is it from u/.8vks )jqb uws?

  Estimate the speed of a galaxy that is 10 billion light-yeut))ve+t, he xars away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of dnzrn,:m7q 5apacku4,xvo g 5 (+ zzb5a star which is 100 million lightx, az5z a4+dpog(c55quvm ,:r7kzn bn-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 K.c1xjt*054n)m6 qg3h ek yoft y What energy (in eV) does this correspond t5 qetf xymn 4j6hy*t)g3 0ock1o?