The appearance of the great range a:yhhpoo: *7f of brightness among stars is due to

  The absolute luminosity for most stars depends on the dtap288gi9mq

  Four different main-sequence stars are colored blue, orange, red, and)7 w*dhx30qxwe*ah3y9fy ogi yellow. What is3ya0d)ex37ghx *ywwf9oih *q their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars o7.g9cvrzeks*eo0yy3,u a p 5rn a plot of

  A white dwarf star with a mas)3u)zo y( cdlss equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collatvaed+ge)2gs3 l h4z/pse into a white dwarf) i lh)2gg eva3d4zt+/ess, if the mass of our Sun is M, about

  Supernovas are thought tofde;ba5 a6(g*btylh i4g :03f*wpooz always result in

  Black holes

  Pulsars are rapidly spin.hnxfnip7m-1 d x2jtc3: mlp 1ning

State Einstein's principle of equivalu/ v2 y r3zcp1z+5bhaf7-an wmence.

  The Schwarzschild radius of a black hole is that radial distance from the centeq pf)y3e wly 4727ibdbr of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general i7d lbby)qw23fy4e7p 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 visible, an3 -cwhy7b (z4w tl ztwbys/raa: a936md the source is moving away from us, the color of the light7 4 c-ata3y t zsw/mba :3hry6zlw(b9w appears to us to be shifted toward the

  The cosmic background radiation corre;sfh-c6)vysj fx* 0jzsponds to a temperature of about

  The Sun has apparent brightness at Earth ig*ura 3vg(*rn vvx veiam+98b;9c( d($1.5 \times 10^{8} \; km$ 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 gi d,6s rq)1 s9h9qlff7 u)chuequal 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 g9e ) om0yn2(mqk-dni 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 radius 7;sm:lfce, )tm6e6p tfbmtl pw7xs7 )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 Earth's nearest star ,g na sb 91vk)xqij),h5o8 xq8y kj/cu;wc5dqavq x5j,8 )hcc 8qa/;gqk )ki9n swj y1,bouxd5t 4.3 ly?

  The apparent brightnesss,wl7vc5u-v) e zpm.p 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 uepl3q; d4j 85dv da4:npdbv/ age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age 3n84a ;v5j bddedl/ :vpq pud4of the universe, in years.

  If a galaxy is moving awjsi lu 1 83cvk28.vv ,oapi+g m3as6jhay from us at 1.0% of the speed of light, how far away is it fris oj2 .i,1la8 pv 3 s+k8vcgm3auhjv6om us?

  Estimate the speed of2j- )doo7ydq w a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in fg7 1l67 9rsg fis6p/tv v*ewsthe spectrum of a star which is 100 millio e7ss i6t/w1vvpfs7l g9fgr6*n light-years from us.

  About 1 ms after the Big Bang, the temperature of -mw;l a*v+xof the universe was about 1013 K. Whamw- l+a*ov;x ft energy (in eV) does this correspond to?