The appearance of the great f m-zfu j1*got.5pa9 qut +bu+range of brightness among stars is due to

  The absolute luminosity for most starsy g(p5vwt,cx,/wt fk 8 depends on the

  Four different main-sequence stars aj r+yb.o4rj psw*fjb:1-nfe.re colored blue, orange, red, and yellow. What is their rank frbn r :bf4rjpe .fsjow*y-j. +1om coolest to hottest?

  A Hertzsprung-Russell diagram shows starznqud on-5 v) )zb( -xjbl9r.es on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the size oalr7 uommi+8 jjz 1kmt2j: +.3dxd/ud8-zm o cf

  The Chandrasekhar limit of stellar mass (below w)1z:jpg(c fbm hich a star will collapse into a white dwarf) is, if the masfc1(j)zg:bp m s of our Sun is M, about

  Supernovas are thought v(5dl js)1qorto always result in

  Black holes

  Pulsars are rapidly spin6 -pe) nhmyqfum9 bt.0h rju..ning

State Einstein's principle of 4 lf+rh k2t nx*:cltno29im7qequivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cesd2q13zg; a7f+ngujf ykf6 ,i nda;2pnter of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Eins2 6 3 j; gdgy72uapi,d +fsfzk1nn;qfatein 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 emits light of a particular wavelengt .7t1wobqx 2ylh in the visible, and the source is moving away from us, the color of 2xyw t1l 7.bqothe light appears to us to be shifted toward the

  The cosmic background radiation corresprsfp -n dr5-(honds to a temperature of about

  The Sun has apparent brightness at E ua:l + j7-) k/xweyqdgg eh8-dx*fk/zarth ($1.5 \times 10^{8} \; km$ 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 the9qu-b4jw:u zlik11v6 t9add v 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 radivjmgu 18 wkd09 6dqkkhm;pr 7u0msn/i4 l2a z:us 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 meann:a3;mymjm o g,r2 u0t 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 iu5b .kf3j1i:pr 2;p9pk3k srl0rw veps Earth's nearest star atie.urlrv0; wpp 3f95j2 rk 1ppk: ksb3 4.3 ly?

  The apparent brightn7-ytbz;1q:gthmk,mvd0/ i dv ess 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 thp6,d su6eh06-sia yaxe universe is 1/H, where H is the s6 ad- ,x0ieus 6p6ahyHubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us a0d lhj w/v7 znk7-(tsct 1.0% of the speed of light, how far away is it from u7vsnc-j(/ 7wk thldz0s?

  Estimate the speed of a g+z7,gh zayx+ yalaxy that is 10 billion light-years away.

  Estimate the observed wave h* g2rfakd v+i9;slh9length for the 656 nm line in the spectrum of a star which is 10si9 lhrh;k9d2avf*g+ 0 million light-years from us.

  About 1 ms after the Big Bang, the temperatuioihda5l 3 5(fre of the universe was about 1013 K. What energy (in5aoli d 3f5h(i eV) does this correspond to?