The appearance of the great range of brigkfrz;fk gq:e6t+ i27 lhtness among stars is due to

  The absolute luminosity for most stars depends on theu.q2-*5mf qfifw (h cn

  Four different main-sequence stars are colored blu* z2t/dvnpq y03z w1wrr ,tzg8e, orange, red, and yellow. Whaz01 yvqzn tp2/ t3dg*,8wrwzrt is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stavoaqmag 0e90ij 5ji ;6rs on a plot of

  A white dwarf star withflfn6k wm ff +k2),,n 1uxlrs: a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellq7t-x.z t79 pp5cs :mgdo+li bar mass (below which a star will collapse into a white dwarf) is, if :7xgpd 59q7+. - mtoistlcpzb the mass of our Sun is M, about

  Supernovas are thought w6.xo 8xj2vw-+giprj to always result in

  Black holes

  Pulsars are rapidly spw ) fpbp3erivx0 .mxfk(k92p2 bg 8:yuinning

State Einstein's principle tqx /,*n o3xu nz6l*dkyg/nrf:o,;wb of equivalence.

  The Schwarzschild radius of a black hole is that rf fj11gr6rnjy/9 vc 5uadial distance from the center of a sphere within which not eveun j rf9y 51fjcvr1g/6n 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 t5y/w, drvdsma+ z0o/lhe visible, and the source is moving away from us, the color of the light appears to us to be shift d+ rysm,05zlvo/w/ aded toward the

  The cosmic background radiation corresponds to a temperfi tgbu:.d-5iature of about

  The Sun has apparent brigouqe4p 3 4-+xzsw8gln htness 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 lumixu *nyskku(6(+e2csq4ewg +c nosity 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 mean radigboh-1 hfirx 22ob 76obn+y )qus 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 mezao0a1 c,flrw +pj 6bp:e70mvan 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 Prox o ) nmdl/i8iqa2q,g*jima Centauri, which is Earth's nearest star at*/ qmojiqdnl, 8i) g2a 4.3 ly?

  The apparent brightn-p,i98b6z-z7fkq;vrqi b 5ek rdn7h 5vx2lxoess 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 approdi l+n0d0., pntwiluo.2 g z;25czmrpximate age of the universe is 1/H, where H is the Hubble co;t2502rlio,zgz p d+.mc0i pn uw nld.nstant. 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 thiw: st5ob;xs8b tfttv+w fhxv, (o zz+(b:;8b e speed of light, how far away it( vb(h:+wf; :zivto t5swb8+ txxs; bzfo,b8s it from us?

  Estimate the speed of a galaxmc *z)/ lvim+sy that is 10 billion light-years away.

  Estimate the observed wavej( cpybc*0eh6 (sezii 3 843 jd8l-m6kfwfhfz length for the 656 nm line in the spectrum of a star which is 100 million light-izje4 smw(63 (cff*0 b3ij- h8ch plzdye6k8fyears from us.

  About 1 ms after the Big Bang, the temperature of the universea2rv/ kl01hd *d2/zp5vwl; baxqnj z9 was about 1013 K. What ezpdj/aqv2klz*91 /xa w2lr0 hvnd5; bnergy (in eV) does this correspond to?