The appearance of the great range of brightness among stars isf-sn9*lsb2dtx y(y k; due to

  The absolute luminosity for mosnv3v fx 6.liemq /hw*2cl+*lot stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yel jb2hvzj:l wi9ljaz 06:z x3d6low. What is their rank from coolzjxd 6lai 3zbh:wj2v0z:69j lest to hottest?

  A Hertzsprung-Russell diagram shows staf.09 z9kg aaxnoc98cs rs on a plot of

  A white dwarf star with a mass equal to that of the Sun is -zvn.-i ,uuf oabout the size of

  The Chandrasekhar limit of stellar mass (below which a u *bu hos;hx/dg2a-ngwek8); star will collapse into a white dwarf) is, if the maseu wx a)/*- 8huo;d sgbnk;h2gs of our Sun is M, about

  Supernovas are thought to always 8bh*b tk(lzt1result in

  Black holes

  Pulsars are rapidly spinnijg1.0e0tw+ ytg;*r oy rcf/mhng

State Einstein's principle of equivalence2d+p 1jkghh.j .

  The Schwarzschild radius of a black hole is that radial distance from as( zcfgppwc 81cv:0, the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativity theory. It can bep:8c zg0vwp,cs1f(ca 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 particulara(w93kocb m d, wavelength in the visible, and the source is moving away from us, the color of the light appears to us t mkd3o b,w9(aco be shifted toward the

  The cosmic background radiation mhh/n;;vni: o8iv3t.eq6my x corresponds to a temperature of about

  The Sun has apparent br5 b )ex/i3ia:b.cd nlpightness 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 that of the Sun (ra 12 /1/irkqml *wouc$1.5 \times 10^{8} \; km$ 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 mea )6ja/jxxd4, q: jkrql8rmv-wjxo m3/n 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 rahnh5p(i x2 tlxnq;dosj7-8 *vmpr (a- dius 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 fotj. rb(8aus *q h6rl*er Proxima Centauri, which is Earth's nearest star at 46(8 tl*es abujrrh *q..3 ly?

  The apparent brightn5s :jdjlnu-y0 ess 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 approximate age of the un4r :rt 3gw .,i,w iwevrcx+0vpiverse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, esw4vr0trwg i v, ic:,r3.xwpe+timate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, hk0(h7d8 r3 gcpwewg3 iow far away isg0pd3w(3w8ic7r k ehg it from us?

  Estimate the speed of a galaxy that is*.5 1g(zuczbp2rqx 4ox e-yiq 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spect1tz5k1hoop 6az n6pk4 rum of a star which iso6z 54pn 1o6hpk kza1t 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe cshui:yq6(9 7tb4 oxt br)/mg was about 1013 K. What energy (in eV) does th6rt7yxb 4) bmios9/(cugh:qtis correspond to?