The appearance of the great range of brightness amon+e.l p:h)scpu g stars is due to

  The absolute luminosity for most stars depends on ths s3 7qn:tgvk4srsa-x5w6v -he

  Four different main-se sr3 3zatu/q:j nxx1*ym r+uk8quence stars are colored blue, orange, red, and yellow. What is th+ uzrarmq x s1:n33/t*jyxuk8 eir rank from coolest to hottest?

  A Hertzsprung-Russell diagram shrieo-wv tmll a.b88 1(ows stars on a plot of

  A white dwarf star with a mass equal to t gf+ w9wja*8se. 7syzcp1-kuohat of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will r(p fsc0/.t gr*d2x/oa6u y cbcollapse into a white dwarf) is, if the mass of our Sun is 0sd pfx.*rcr(ya/2 /t6 ubogcM, about

  Supernovas are thought to always resula b 2/e5,crwj;gj8 owit in

  Black holes

  Pulsars are rapidly spinningn fi) 15clr dlx4btwjm0d,gl.,4x pb tn:ou0.

State Einstein's principle of equwc48 tafrhpg:97hn1s fym9 b5ivalence.

  The Schwarzschild radius of a black hole is that radial dist0(z xd(ea f)fxance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativity (dzf( e) xx0fatheory. 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 +3ma*bv ucbwti 72jug,o4xs.the visible, and the so.sb ci3ub og4, u+7x2m* wvatjurce is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperatureclns)o2gd w28 t0kq4q of about

  The Sun has apparent brightness a rcdfh-(6n8kigu,r+t yqw zw;gz, u/0t 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 the Sunwj ,t un*.53rnyp-gc x ($1.5 \times 10^{8} \; km$ 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 rad,8amxc p,6 bg1c1obvm ius 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 hast yu8bevm9x0leohh2+o7w85a 2/j cs m a 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 Prp85blph9;y3*ivqujo p n *i1moxima Centauri, which is Earth's nearest star at 4*obmp 38 uqpp5nl y9;ijhi *1v.3 ly?

  The apparent brightne1ud5 )9nfffe jj cvx07ss 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 approxim*x sk3 yy(u*6y ic4wbh)o:k*y3zi wrjate age of the universe is 1/H, where H is the Hubble constant. Taking Hzsjykou*xki icby h): y rwy*33 (*6w4 = 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 ,9 run8oktfc4wi0wc7 speed of light, how far away is it from tiuf c8on9k07c4 ,wrwus?

  Estimate the speed of a galaxy thx1vc z h8wk 6.ma0qvr(at is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrumxrtmp9 wo6fx/ nq8n)7 of a star which is 100 million light-years from us. 8)m7wn6 n9 rxtpqxfo/

  About 1 ms after the Big Bang, the tempera+g1( 1hx btfmr 7q8lkjture of the universe was about 1013 K. What energy (in eV) does this cor(fr t1 x1k+hbj7ml g8qrespond to?