The appearance of the great range of brightness among stars is due )q7f -dcb *6qqf z:x.yeij 4into

  The absolute luminosity for most sjf47 jq5ks 7.knqek+lfno 5u+tars depends on the

  Four different main-sequence stars are c,uv(8nirh + 8og ;qytn5i mc9oolored blue, orange, red, and yellow. What is their rank from cooln vm+nuq; i5,cy rhi8go8to9(est to hottest?

  A Hertzsprung-Russell diagram show/aqu6e f)( xya cd7*of 2b;wnzs stars on a plot of

  A white dwarf star wi /lp,*pg,hbzk th a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star ws z;oi tjp,w41 7)k)pxr)gpdeill collapse into agzit)pj4 wxkp d,e1 )os)p;7r white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thougw-1wk,/t arks 7hjy;kht to always result in

  Black holes

  Pulsars are rapidly spinlc9daj7g, zs;uy5* 8r t exts/jvqo*;ning

State Einstein's principle of equiz:7xiq),qy:5w g,; dhw ykmvavalence.

  The Schwarzschild radius of a black hole is that radial dij n 9i(q+hja;sstance 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 ge +j9q;sh nia(jneral 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,ojm(k pdr(x/ m csww;5l;7f a) and the source is moving away from us, the color of the light appears to us to be shif;(x; fw7ap(/)m5krl sm cwojdted toward the

  The cosmic background radiation corresponds to 8-a zt8d0cdg90j fxqga temperature of about

  The Sun has apparent brightness at 6bq1m-bsmd(hyf - v0oEarth ($1.5 \times 10^{8} \; km$ 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 lu,vz9+s)i wk2o1 ur dajminosity equal 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 mea: w3wqr1zyg) oa,wg.bgl*1eyn 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 radiust .g r89hok (f yd(03v scy+hd x5nj:4zwr:lqw 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 neu cz8m r,)t-jdw)org;arest star at 4.-c rmog)w8)rjtz, ;u d3 ly?

  The apparent brightness+n52wtzsez3:6z+y nz ux58.l yofp td 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 appk bc/vy3fm h 6o u;+jptjd gw2dx;;5v3roximate age of the universe is 1/H, where H is the Hubble constant.uvxm; d+6;wf /b oydh33; 2 ptcgjj5kv Taking 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 the21 ns3j/cxl 0lz9; vt5g(sz7 jxp xqhy speed of light, how far away is it9jxx 1;0/l z(2 ypls7 xz5hnst j3qcgv from us?

  Estimate the speed of a gal7kjr/(mr, w q2;wpvs3sb 0cbeaxy that is 10 billion light-years away.

  Estimate the observed 7bb9sscp )8fv wavelength for the 656 nm line in the spectrum of a star which is 100 million light-ypbbvf ) s97sc8ears from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1064x9h;2bl:yvxzn zvrv t9f y gl1s -z513 K. What energy (in eV) dlfvgntvy;6xv:s 94 2 z5b zyl 1rxzh9-oes this correspond to?