The appearance of the great range of bh)rjj3a2 9b/.dus qfcrightness among stars is due to

  The absolute luminosity forptsm pc j3 h3-+mnh4aa-6ck 4k most stars depends on the

  Four different main-sequence stars are colored blu6bi:x5 57-knhubzb ore, orange, red, and yellow. What ob:z6 -xb u7n brik5h5is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot ofh 5hv/0);rkwk( r xaik

  A white dwarf star with a e1*r k2n1vsu pmass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar ma6 82rrfovo y3kss (below which a star will collapse into a white dwarf) is, if the mass of 3 yorrfvko 826our Sun is M, about

  Supernovas are thought to always resub28gq; jt*x2hxw ej,7m,ge nslt in

  Black holes

  Pulsars are rapidly spimzv ngdz,1: :,vyuif: nning

State Einstein's principlr;:4q8ev 7 ig m*y-iqjn v9+m3xiou vie of equivalence.

  The Schwarzschild radius of a black hole is that radial distanc0rxvb e9y0)mmferd m3 j-0zu6e from the center of a sphere within 0xz3 )9vjm-e0rrm fu yd6be0mwhich 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 emits light of a particular wavelength in the visible, a16-sa m 40xmu/ylnjhznd the source is moving away from us, the color of the light /uhn6m1lx0m-4yza sj appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of a (a(v 3wzceu5plmv/ 5fk0ucg .bout

  The Sun has apparent brightness a s-lkw y(9wsw-t 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 y;(6ib acal+ff7sj 1dequal 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 hasd.b5c) a ju3zl 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 km?

  The Earth's orbit has a mean r6(; hqxg2fflx.tzy1eg f,s2u a+j1c 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 is Earth's neal* pb8*gm+l mm(eyrvwx+ pq1 3rest star atm lvbr qwp(egx ++8y*3 mlm*1p 4.3 ly?

  The apparent brightni, luyi z)us2s+j5m f+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 s5,x mveqll* /of the universe is 1/H, where H is the Hubble constant. Takieqlsvxm 5/*,l ng H = 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 speed ofjnc, njdl.. tl+1p. mo light, how far away is it from dt +.po,nj.mj.nl1lc us?

  Estimate the speed of a galaxy2m q4 a4btav;-a-zfh c that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm linetflx .*.pb dj70-nxu w in the spectrum of a star which ispnl *7 .jfxu0-. bxwtd 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was aboutc*3ng9h mr7kd0w 7d j z:qf.pp 1013 K. What enerfwkpnm q p709*c3 .7g:rddhjzgy (in eV) does this correspond to?