The appearance of the great range of brightness among stars is due k ek jp5rq;x43+i 4ldmto

  The absolute luminosity for most sr mqm3:j5g go+ 6oxz:otars depends on the

  Four different main-sequence sn x bwzs/x3 mm5;m8il/tars are colored blue, orange, red, and yellow. What is their rank from coolestwi3 bmsmxl5n;8/ z/xm to hottest?

  A Hertzsprung-Russell diagram shows stars on a plf c9 (o; ,:wl6btuwyvzot of

  A white dwarf star with4i3ta c u/w-hn a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse in0966d t z1 b/gwtm6xvfpl9 zzfto a white dwarf) is, if the d 61gf6 6z09fxlmtwz9bt vp/zmass of our Sun is M, about

  Supernovas are thought to always resulk/2 qe0yqelnfrda8,7 o hyb+,t in

  Black holes

  Pulsars are rapidly spinnindm1a*r( .1gnw ayrki59pbv3lg

State Einstein's prinkeg .-h-a b4p- i,iweqciple of equivalence.

  The Schwarzschild radius of q:fk) 1oa5 frja black hole 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 Einstein published his generaoj:faf1r q5)k l 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 wavelength in the v .7gr1 3l6z8.n6pht/,n:e urq2rspof reblt xisible, and the source is moving awa r. g/ 6lrn3qrpe bh8p2l,s1tuotx:z 6nrfe7.y from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a tempernk 0 yiwgp/p)wxq5o- v3 vl gy4)b4fj2ature of about

  The Sun has apparent bri3)x3nx vuzsy:x,vz s.zi+zw82.v mz g4o+we qghtness 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 lumco9j q(bxj:m+b0by 6 finosity 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 of b-rwvh5 * waw .jw)it9$1.5 \times 10^{8} \; km$. 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 meanl2;,v+- rn 8z0at4fz; y usl26, xkwogbtfdbc 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 Centauiyn jy,a7mwsy idi5:r6 x xd8j3;*dw 9ri, which is Earth's nearest star at 4.3 ly?86 mixjdj9aw* ni7x ysyirdw:,; 35dy

  The apparent brightnes0r2qp)a l /vwm+ v)urfs 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 tj. nni;jaa7 .ahe approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of t. an j;a.iajn7he universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of ligpzgl* m ;j9fy.ny j667 oyko9dht, how far away is 6 9gnjo9; f7.*zolpyjk my6ydit from us?

  Estimate the speed of a galaxy that i.juvxr8(( ed js 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in thev9kbm aze. o-, spectrum of a star which is 100 million light-yom ,b9 vke-z.aears from us.

  About 1 ms after the Big Bang, the temperature of the universe was about fy c)8j:)q wzf+i3,g*18 kvajp djqls1013 K. What energy (in eV) does this correspond to?1:jqj idzqj)8cw)3k, pg svf fyl*+a8