The appearance of the great range of brightness among st ( ;xngkg1;reuars is due to

  The absolute luminosity for most stars depends on th 9z43ppn*lvug e

  Four different main-sequence stars are colored blue, orantc :oa*0wbw 0pa;0zwh ge, red, and yellow. What is their rank from coolesbh0aa0;*:wo c0w ztpwt to hottest?

  A Hertzsprung-Russell diagram shows stars on a ploqet, 5ogn7n2, sj1umj t of

  A white dwarf star with a mass equal to that of the Sun is about thkj w3304opqqdd d9/ cewcqr0 0e size of

  The Chandrasekhar limitm-u .a.1jt 2mrri6d/zecd.xtp i v)6o of stellar mass (below which a star will collapse into a white dwarf) iscjv-.z1.6 rtx i md2trma .e u/i)6opd, if the mass of our Sun is M, about

  Supernovas are thought) krc a-gezy9a3/pa v3 to always result in

  Black holes

  Pulsars are rapidly spj9g0l2g ;59rsfan dl7k u(a(tfoxql6inning

State Einstein's principle of equivalejm6p)w 4jm cnf3 cc:h,ftjh/pa : 9hr;nce.

  The Schwarzschild radius of a black hole iyb3.ba0l/j e 01e , rskngts2fs that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 afterka geyb.st0n2er1/s f ,j 03lb 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 wavelg0:: rqhoiv*kyzz8yags o h1c9 +p.8uength in the visible, and the source is moving away from us, the color of the light appears to us toog808 :hcq9y: o1*zhgu.ry+akizp sv be shifted toward the

  The cosmic background radiation corresponds to a temperature of about;ypq;cpf41/2 yk vc kd

  The Sun has apparent bright4mxwss jp0 rb802a ke2ness 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 to thatfo 03e idront9c4:u8 r 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 hasc+dby )8xw0d yl3wv9lziju,) 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 -dbuols3nqqy7( el( *h4v* fd 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 Ce 10p(wq(pfw s/ 6o:fc*ldr7ax ntx a:entauri, which is Earth's nearest star at6f(s71f o:nlwp q /dc0w*:xprex( a at 4.3 ly?

  The apparent brightness of a.0k zuc/hvb)x sf+5uw 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 univwye6r ip,p7y/2y9 :a er0c cederse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate theipc 2,ay r07dwce:9re6py/ye age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the89 yxqz8d 5 0q;znwljj speed of light, how far away is itxn; 0yd qj59q8lz8zjw from us?

  Estimate the speed of a galaxy that is 10 bill;f9oic2*2ucwarw c( jion light-years away.

  Estimate the observed wav9h4el6i.ly yo 50t vdgelength for the 656 nm line in the spectrum of a star which is 100 million liy t 69oilgv0he5y ld.4ght-years from us.

  About 1 ms after the Big Bang, the temperature obu8b.i; z 6ee7pt g25by3zjoif the universe was about 1013 K. What energy (in eV) does this correspond toj62 uy;e 3zobgi.tbpbzi 785e?