The appearance of the great range 9 iua mvb,9u7wof brightness among stars is due to

  The absolute luminosity for most stars depew:xr-/zfg -wl nds on the

  Four different main-sequence stars are colored blue, orange, red, and 8qi1bigqs,p3kze s2 .l) au(kyellow. What is their rankq)gbi 38zs p sak(2e1u.k ,qli from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on amsiijub;11* 5gz9q8scm2u m 1uk wb. t plot of

  A white dwarf star with a ma uzsyqaf.jbv -e p8)2w :-kcxr6(rrk(ss equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will co-.nan2xmzbc hh,* c1,ao* pemllapse into a white dwarf) is, if the mass of ouh -*nh* manbc12xoma,z.p ce ,r Sun is M, about

  Supernovas are thought to always resul;qrunp7cxw )* t in

  Black holes

  Pulsars are rapidly spinning+ n.*ecefhh 50jfg6w,uw a2sf

State Einstein's principl6mxu;n3iy5s2c5 ltq .t p u72tru6apc e of equivalence.

  The Schwarzschild radius of a black hole is that radial distan0 5go1oe4*yy ew+k(osfbw2 jy/lp0 ii ce from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein publki( f/ p02s 5y*ybjw4 olwyog i1o0ee+ished 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 w;elpqi2, ,ci vgz:0mbavelength in the visible, and the source is moving away from us, thez q,;2:ivemibc,gl p0 color of the light appears to us to be shifted toward the

  The cosmic background radiation +s(*x 7hjaiq iu g+veyb195ymcorresponds to a temperature of about

  The Sun has apparent brightnei 9uwutat4)l2 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 luminosity equal to that of toy7nl6 74rp )sv 0tfsjhe 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 off m yd3 /ps-sxvj1)yr (7gd4tx $1.5 \times 10^{8} \; km$. 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 ac9 ogxso:m 44mq u/m0, rw/zdb 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 vc nrwbz98 q23cn25hv Earth's nearest star at 4.3 3 z2nv9nh85c2bvwrcq ly?

  The apparent brightness of a starjagvy6n +8tlg/+qt( v 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 thatwyds7n d k mje(cl,.*eq*:ah9gy + (wa the approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the ageqac 7w+*k:ea* .n(9yhswdjdel,m g (y of the universe, in years.

  If a galaxy is moving ;cps (m) p3nham) ys;raway from us at 1.0% of the speed of light, how far away is it from us?y;)s pm;m)s pn3ah(cr

  Estimate the speed of a galaxy that is 10 billion light-years away. +6uuz 7zns:ao90i0k u5jdqz r

  Estimate the observed wavelength for the 656 ljazb+j5g 8 3enm line in the spectrum of a star which is 100 million light-years from usj3g l8a jz+be5.

  About 1 ms after the Big Bang, the temperature of the universe was abou s f+-7rmqlvj )7cfud us,m;x-t 1013 K. What energy (in eV) does this correspond to?+ x ,-svjdufrqm7fsu )c -ml7;