The appearance of the great range of brightness among stars j;4hc lij p66wml* gr1is due to

  The absolute luminositipe.5ofr +vlto8; y)* tv7n wer7d5fzy for most stars depends on the

  Four different main-sequence stars are colored blue, orangex6f7.fh edx -fmn52aty)4kup7 q a (nn, red, and yellow. What is their rank kannfhn72 qa76f4xp .dx-(5myteuf) from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a d 5g8ajo1x/zy plot of

  A white dwarf star with a mass equ c-:mse. hapkldhpd v5 mmk*+f23,rh9al to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below whitv*w y)ise*n 5ch a star will collapse into a t 5)sey*iwvn*white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always rob a55ii y:hj gv4f4t)b9gq l0esult in

  Black holes

  Pulsars are rapidly spinni*6eyd4gu 8fm hd9fd p k/3(kr + v7scjmaqp7m7ng

State Einstein's principle of equivalenoqi4q8j :eu)nh :kj.x ce.

  The Schwarzschild radius of a black hole isf mnfcdm6: k 2;-*ugwo that radial distance from the center of a sphere within wok dcn*m2fw-f6; gm:u hich 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 v6hf 6gws f7:rsfj-8f risible, and t-:6wh6s f78g rfsfrjf he source is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperaturcox*+fed.p0jfyujo*t u 18 ,/ti yjw(e of about

  The Sun has apparent brightness 6bzl4z ow4s d twb9r34at 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 that vt0/mj9now86pulcu 0 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 radius d4 2v1v, twpzvof $1.5 \times 10^{8} \; km$. 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 zef. ynl 667t3 wkk8+mes0*r8jsshi da 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 1ziy (ear+h 3qv8wfs+3x gd5 tProxima Centauri, which is Earth's nearest star at 4.3 ly?gh+335it+8xa q rz( 1wdsfeyv

  The apparent brightness ofj9tzca kf):coax n-r d*;5og6 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. i6jk-g 2zolc, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimak - j.zoiclg62te the age of the universe, in years.

  If a galaxy is moving away fr(ll kkfb)uf,+ tlwj7 (om us at 1.0% of the speed of light, how far away is it fk(k, lwlf f(t lu+7bj)rom us?

  Estimate the speed of a galaxy that is 10 billioh eb;1hge:p2u9 kmc6h)tta-vn light-years away.

  Estimate the observed wavelength for the 656 nm line in the sx+9gvxd v1q(p7ckbx:ds p2o3pectrum of a star which is 100s2gq:o ckx7v+(b x319vdpdpx million light-years from us.

  About 1 ms after the Big Bang, the temperatur 5myc++n(kcm-4t k yiqe of the universe was about 1013 K. What energy (in eV) dotiy yq-+ckmm5 +(n4ckes this correspond to?