The appearance of the great range of brii ,adx2b9v aq7ghtness among stars is due to

  The absolute luminosity for mo 1sskj0q52x8oe(h td vst stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yellow. lq)v,2vp82c c*eniapsn0 *wa What is their rank from coolest p2p 0v )e2ivl,q8a*wcncs an*to hottest?

  A Hertzsprung-Russell diagram shows starshpjhx( epc31d+ f,a2/sto q.s on a plot of

  A white dwarf star with a mass equal to that of the Sun ic2a3sg* cunu0)/ z e5*yg.uz r.artces about the size of

  The Chandrasekhar limit of stellar mass (below which a starnd;woytk1b9q 27 bj8e;b lmq, will collapse into a white dwarf) is, if the mass of our Su1q8b b 2tqo; ed njwby;k7,ml9n is M, about

  Supernovas are thought to alwayhsmx :t/ fy 7rtwaq ;6vhhg3 18iitp:*s result in

  Black holes

  Pulsars are rapidly spinn5asg9xclq. k/ ing

State Einstein's principlp( yl()0vjuo me of equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the centiwceq3 my*l ewsz381- er of a sphere within which not even light i*31wsmc8yel-wezq 3can 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 pgfus4 *69bve u6yks9har/ gwbt+x hy3e4k w09 articular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shiftx 4e 0u9bw /gty vk+bw9 sefkurg s*h636a9hy4ed toward the

  The cosmic background radiation corresponds to a temperature of ahplwc)fo v/ mv501eujd b t)/5bout

  The Sun has apparent brightness j42/qs;jkpji 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 equal togp:7+ upwh0m nurgk- ) 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 mean rlg/cy8 m mw5 nat9bu;8adius 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 atsmiszr(ou6 535x ;0uj ktu1j 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 Proxima Centauri, which is Earth's nearest syc qsvih 9-,q;tar at 4.3 lyiysvqqh 9c;- ,?

  The apparent brightness jf4zr;pqn* 8ba h 9z njgs67n/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, uiq yh4w v2 mw3bniy:b160 d3rwhere H is the Hubble constant. Taking H = 20 km/s/Mly, estimavbu16 3rdw:0 iqmhybw4n 32i yte the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far awa 6vzc0rw- yrk-0zn pt;y is it zvy--rwp k r0zct;06n from us?

  Estimate the speed of a galuf 3wku .of1f3axy that is 10 billion light-years away.

  Estimate the observed wavelength for the 6jw- iayo6 y)9n-w7a wy56 nm line in the spectrum of a star which is 100 million 9yio awayny --wj)76wlight-years from us.

  About 1 ms after the Big Bang, the tempe*wgrvx h ,c )xy3(nc.prature of the universe was about 1013 K. What energy (in eV) does this correspond to?g *n(whr cpy.vx),xc3