The appearance of the greaq2 / x5d1jyzuat range of brightness among stars is due to

  The absolute luminosity for most starejsban0rq2f2qtfe8 zu14h5) 3s bvs . s depends on the

  Four different main-sequence stars are colored blue, orange, red, and yellow. W9+k+xd 3 gab+5 miwivw/lnt; ehat is their rank f; ++ginm5w/+la xved t k9b3wirom coolest to hottest?

  A Hertzsprung-Russell diagram hm ).ga0x 9thbshows stars on a plot of

  A white dwarf star with a mass equal to that of the l.bhxi ;7ua512n qg gmSun is about the size of

  The Chandrasekhar limit of stellar mass (below whicm,lt0f4pn i2 .wqpv -nh a star will collapse into a white dwarf) is, if the 2 wpl4,n-.fpq0v imntmass of our Sun is M, about

  Supernovas are thought t(hjvo yzsbel mi,4u v3u7le . (/)lgm:o always result in

  Black holes

  Pulsars are rapidly spinr+s mv,;1s ujifa -id-ning

State Einstein's pri;efj8ygb+/e,otd)+wqb 2d.p ht uq e. nciple of equivalence.

  The Schwarzschild radius of a black hole is that r 88cwn g2giio,od jg7/adial distance from the center of a sphere within which not even light can escape. It was first discovered ma wgcn g/gdj8,o28ioi7 thematically 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 wavelekqa3j, 8 0d-hm omog;yngth in the visible, and the source is moving away from us, the color of t 0g;o, mjq3a8hm-oydkhe light appears to us to be shifted toward the

  The cosmic background rad5kzg b vy091*jcj :lrwpi :dqw18hh k-iation corresponds to a temperature of about

  The Sun has apparent brightness at (o-)ra :z. osbfxq.krEarth ($1.5 \times 10^{8} \; km$ 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 equ+7obsl1 v5tu17iww qe r jx9)bal 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 f0m cmx4ec xoc+0a l50iheu79a 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 v vs:k-f /885o intyhsradius 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 Centauo6 .nkbc5 rzfe:mf1x2ri, which is Earth's nearest star at 4 kr. 5xbf21f6 ne:mzoc.3 ly?

  The apparent brightness x714d hufd; 83v.brsu5c(c uyd(abaz 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 approxi2zbawj((q1 esep7(u lz,; iyimate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of tqwaee b;ls27( ( py,iz1(ijzu he universe, in years.

  If a galaxy is moving away from us at 1.0% of t;(bs+guwt5y dubw/4krmds 3o/ qg2rgmr:i/0he speed of light, how far away i;/twyq 4urgb+3mr/ m dsdggr2su wbi / 0(5ok:s it from us?

  Estimate the speed of a galaxy that is 10 billion light-ylxad9ri(0+p94l; kc jf qagu- ;fzka/ears away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star ede3wew6 2g/ yc9bl6,ukuui vc -a; 3cwhich is 100 million light-ye/ic3, 9yea ve k6cg3b6 w-lu2c eduwu;ars from us.

  About 1 ms after the Big Bang, the temperature of the univv/zz l-*p*usberse was about 1013 K. What energy (in eV) does thz/-l*b*vsu pz is correspond to?