The appearance of the great range of brigh6e8 xt5xy uj sd4cc+l) ihtwe*d z7)5ttness among stars is due to

  The absolute luminosity for most stars depends one2dng l pu6s,x)-scp: the

  Four different main-sequence stars are colored blm,1 yraor8i tz6yw :yxsi/i) p7q/ u-lue, orange, red, and yellow. Wh6xr):m8/u 1wroi-p/ii aqy,y ztsl 7 yat is their rank from coolest to hottest?

  A Hertzsprung-Russell diag /v pmx;nw9m4+f uhpg6ram shows stars on a plot of

  A white dwarf star with a mass e 1q6 rax2 hu+u5mceo2xqual to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star (mzwxk2m8y3w *vwlm)9 a3mp r will collapse into a white dwarf) is, if the mmk8p3*vw ymmww (xz)2ml 9a3 rass of our Sun is M, about

  Supernovas are thought to always resuv.h r-h.f8yx ria6vi;7r su3dlt in

  Black holes

  Pulsars are rapidly sx4)fflg f; ::w 1eaekdpinning

State Einstein's principler7 jp:j7 wmm/d of equivalence.

  The Schwarzschild radius of a black hole cfd p1n 8/ o+s/t2g he3fvtpu761lp owis that radial distance from the center of a sphere within which not eve3hp1l68up/et1sfcodvt p fn+og/ 7w2 n 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 emi(n962a 5uwlt 6h5rriaiftv0pfq58rm ts light of a particular wavelength in the visible, and the source is moqupiaf0nrirwt9 28ma vf6lh 65(t5r 5ving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperat7x6rdx *i,sjhym) y* ln0(x jnure of about

  The Sun has apparent brightne mp 1heg)e+2rsss 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 eqmgvftm2n,mg,/w 2l0z;;h y neual 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 y7mpblqc -(q g(s2x0za 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 km?

  The Earth's orbit has a mean r+wd, u5d xjjy/(+ spriqn0z7mb,0azicc 8( vs 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle vik4 rcj9)hg -x3g0wdezl )f1 for Proxima Centauri, which is Earth's nearest star at 4.3 ll0rvfhk z w gje-134g9)i) xdcy?

  The apparent brightnd lh3 ken/u, ;+lwoxy6ess 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 the approximate age of the universe is 1/H, g0u4nzlub- ,j u7ltbyv; q:1pwhere H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of 40bbtlvglyp:7 n;, j1u-zu quthe universe, in years.

  If a galaxy is moving away fromsmin:rl+p )pxci 8u :) us at 1.0% of the speed of light, how far away is it f:cr+m8p i:)nilx s) purom us?

  Estimate the speed of a galaxy that is 10 billion light-yakytxg6 56fb (ears away.

  Estimate the observed wavelength for the 60abej3olxw ( .l j) sriyv4/v(56 nm line in the spectrum of a star which a3vlsovbjx /ew )j(y(. 0li 4ris 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 10 e,dy.k dr8z)c6js; gu13 K. Whak,rdduc;8zj )6s g.eyt energy (in eV) does this correspond to?