The appearance of the great range of brightness amongx3qslnjq 65;f stars is due to

  The absolute luminos:l9 y:1xu0z3ntp4joulj3 +oy( ayfrcity for most stars depends on the

  Four different main-sequencc,, afdwxc3+3zwoxc7e stars are colored blue, orange, red, and yellow. What is their r xcfcdx73cww+,o ,az 3ank from coolest to hottest?

  A Hertzsprung-Russell diagram shows ; vjuw:xq1sxe7wt(0c :;:vskkf cqv)stars on a plot of

  A white dwarf star with a mass equal to that of th+bj8i.om qv i;98 pueq 8h2utve Sun is about the size of

  The Chandrasekhar limit of stellar mass (below wh yv0m+w.(ryd:jdlb0:sz2xi i ich a star will collapse into a white dwarf) is, if the mass of our Sun is M, abd2 i.mi dr:0zjw+bsxyl: 0vy(out

  Supernovas are thought to acq.g;hr f)pf yql3zx 1,vb33g3oqg+iu7: hrnlways result in

  Black holes

  Pulsars are rapidly u*49z . ep1qn9* clmvfce4mo-blt 2uespinning

State Einstein's principle of eo.py/aflyus0yp6c i 5g + -:yjquivalence.

  The Schwarzschild radius of a black hole is that radial7 *cvqbrtg8su/:dlc;- k7las distance from the center of a sphere7gs7d* a;:8u-tqb /src llkvc 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: $R = 2GM/c^2$. 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 em9i4s7x,0eujaxz +saq its light of a particular wavelength in the visible, and the source is moving away from us, the col q7uazi9j asexx,4+0 sor of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of ab thf2d(+cj 5eo .s*oeqout

  The Sun has apparent g 5i+dx8lg8gt2j +bgzc6r dmf )57sskbrightness 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 luminosit8+ cd. g1w (jwxnyk9ray 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 r7zw vc 6gtqr7md/ej75 adius 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 a mean rad.oihnm f4 fp9 ,g 0k8/ggdq/hcius 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 ;dyymr 0x..gfis Earth's nearest star at 4.30ry m.x ;fyg.d ly?

  The apparent brightness of a star9o014mwz c ygu 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 appro+k;iu 9 rm: omx)q6/v)dot mmoximate age of the universe is 1/H, where H is the Hubble constant. Tako9))6trd/kmo: mmqx uov;mi +ing H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% o bdi d*1p1ll*kf the speed of light, how far away is it from usd11kdlib p**l ?

  Estimate the speed of a galaxy thath 3y4p)5cn*in,n lkefv7bha* ul1i 0e is 10 billion light-years away.

  Estimate the observed wavelength for the 656 e7mrd wx-r,/3oni xq /nm line in the spectrum of a star which is 100 million light-ye,or37i/ xr/ed- xnmwqars from us.

  About 1 ms after the Big Bang, the temperature of the uniosb xu0am/ )c;/0,lp dgfy4r fverse was about 1013 K.mx0lc4fdb,);r/ ouy/0a s g fp What energy (in eV) does this correspond to?