The appearance of the great range of brighq1 n0p z0uy3zsiog /e3tness among stars is due to

  The absolute luminosity for most star2zz8g, iasxvp6 .)vjls depends on the

  Four different main-sequence stars are colored blue, orange, red, andsww:4;ie c tn:ut *b4n ipkw-* yellow. What is their rank from c4nw- e:k;t4ubi:piws *ntw* coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plih(t( j8x cukmb8p(+uot of

  A white dwarf star with a mass equal to that of the Sun is about the sizt)7udxfi3vt-x r8 /p y( +ztfye of

  The Chandrasekhar limit of stellar mass (below which a star will collapseqx0i ) -4rjipv into a white dwarf) is, if the0 -j)qir i4xvp mass of our Sun is M, about

  Supernovas are thought to always resu-- +7vvdv nf+/iigsz(4 kysx pgo(sg0lt in

  Black holes

  Pulsars are rapidly spinningd z;;rgjy dy7-

State Einstein's principle of uld 278 c wb63njdo :ltju5k-n12n hw)0vytpp equivalence.

  The Schwarzschild radius of a black hole is that radial distaunw*qwzuad6 u) e( i;+nce from the center of a sphere within ewa6iq)w *+ud uu;nz(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: $R = 2GM/c^2$. 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 lijgjy nu 8njim:x)l* +3ght of a particular wavelength in the visible, and the source is moving away from us, the color of minyn3:j +jx8 ljug)*the light appears to us to be shifted toward the

  The cosmic background radiation correspo ixdcq .02iue;p+)5j tdix-c cnds to a temperature of about

  The Sun has apparent brightne l61,jdxwp9b yk-0z (xbsm5u kss 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 luminositv )u3 ky6 fenpu65+wwoy 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 xuao 7hkyco4.czy ax 7+ 9(g4xmean 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 d45u t9ldy6jca 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 Pr:8 p 3pldzuvmcfj * 7;xpu;wjvh1), aooxima Centauri, which is Earth's nearest star au: ;,*w jhopfv zcmxdp)ujv3a 8p;l 17t 4.3 ly?

  The apparent brightness of a star is io fd+69i3sndgp7rd5 $1.0 \times 10^{-12} \; W/m^{2}$ 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 ih;t94,l tly( jjxzl) H is the Hubble constant. Takingl;t,hzljiy4x t( )j9 l 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 speed of light, how far away ibjt nr-0y txn4 wh82a;s it fromwtbrhxa2t -0 8n n4yj; us?

  Estimate the speed of a galaxy that is 10 billi,wggt qgj(lw1:md/o)4bh9n6t y, obpon light-years away.

  Estimate the observed wavele5d l4xzkah kd;mk eq7-):,79py otssrngth for the 656 nm line in the spectrum of a star whickek t;:4hk ,yr9sd xdo-s a)77ml5pzqh is 100 million light-years from us.

  About 1 ms after the Big Bang, the temper o8uo(sc:0hd vature of the universe was about 1013 K. What energy (in eV) does this correspond to?s 8vo :h0udo(c