The appearance of the great range of brightness among stars is dna. bxdpc:g1+w3 ft6 1mij)bdue to

  The absolute luminosity for most stars de bax43 takl7 pz8s-eh5pends on the

  Four different main-sequence st:f xs)ylwlv +1t0 jh9kars are colored blue, orange, red, and yellow. What is their rank fr)ljw1v:+y ls9ktf 0h xom coolest to hottest?

  A Hertzsprung-Russell d2rf+ h0pbr1s pqbz h82iagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is abou*k6itko w -v*f( wv7uht the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse iw cqhoz0r(*/i(c hgr4nto a white dwarf) is, i*(o z wi4rg0h (cr/qhcf the mass of our Sun is M, about

  Supernovas are thought to alway o2y+ 7eu-k/bgcfzkh .s result in

  Black holes

  Pulsars are rapidly spin am0wa s 03-szy:ijr4cning

State Einstein's principle ofzt49 hn+l lmf2 equivalence.

  The Schwarzschild radius of a black hole is that rad,jc0 8zfc6n eaial distance from the center of a sphere within which not even light can escape. It was ffnaj80 zc, ec6irst 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 wavelength2xa-(u x5p n1 )n p.q38n:a la;lwdzrmphkg+ k in the visible, and the son1);krk3lw8hndauapxlq:pnzp.g-a m+ 25 (x urce 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 tempeju+ cmzov0v7:rature of about

  The Sun has apparent brightness at Eartgmd/ dcnl2d( p/ejf3,h ($1.5 \times 10^{8} \; km$ 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 i/ytwfq*-) nnto 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 me)qelxpoty2nj*2v 8 9psi/ -qgt,u us,an 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 radius of ra k h2ety+:)p$1.5 \times 10^{8} \; km$. 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 zt6 8ro+tr ao1for Proxima Centauri, which is Earth's nearest star at 4.to 1zt+rar8 6o3 ly?

  The apparent brightness of a+ oqd2lg09/dpx3iwqs 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 univv;wfj 4)ka au-bg 6bl9+pmfk )np.fq8erse is 1/H, where H is the Hubble constant. Taking H = 20k wf.jlngap)8qba-9 b uk;+)vf4fp m 6 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.pe) dca( *eh;a(t9o eaa jx8r:/x1 drj0% of the speed of light, how far away is itd (9r*ao e a( ar ;:/pxa)1ejthxd8jce from us?

  Estimate the speed of a galaxy that iz0mk3:;e wt -1hodngus 10 billion light-years away.

  Estimate the observed wavelength forj8bke se.4a--h* h a.xyn.(pxp n8m- (qzgqpe the 656 nm line in the spectrum of a star which is q e hy*a(nxkpebq8sg(p8.xn--pae jz-m.h 4 .100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 4tnx 5p*ki-x fj+v qk4eq(e g9np,go. 1013 K. What energy (in eV) does this correspt ep nq5*k oqfgxpx(n.4jk,49 ievg -+ond to?