The appearance of the great range of brighws 3w*)o:r +:lk.+sg)fpq gb -yml wdetness among stars is due to

  The absolute luminosity for most stars depends on th zcv(rk(k:gt.e

  Four different main-seqytxcu( ;qets2+ .c+la+yxeq, uence stars are colored blue, orange, red, and yellow. What is their rankx (+s ;x2,cac qu.eqt+y ety+l from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars oni y6jv7eg1fc4 a plot of

  A white dwarf star with a mass equal to that of the Sun is about the size ofnw9ud9as5 ;s pd 4 mc+*gurd3m

  The Chandrasekhar limit of stellar mass (bel1q/oya crxn7t9c(oo* gw 9/t,iy) k stow which a star will collapse into a white dwarf) is, if the mass of our Sunw, )rn 9toagiqk 9 7/tco/y* cyso(t1x is M, about

  Supernovas are thought oqyx9j*6 lp*xy 0fcb* to always result in

  Black holes

  Pulsars are rapidly spinni-:sf0 za-g2 t: eibjking

State Einstein's principle of equivalence. 4ygt xu t dqys3:la;+sl4lgw(z). :tp

  The Schwarzschild radius of a black hole is that radial distance from the c*:por .kfn8g6 yonlge8wz c;, ojao6) enter 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 be calculated from a star's ma8y:po.jr* z ,ol6noc k6gfo)wa8 g;enss 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 vis9dhm4)gsl(smbxjx6;.1xc: f 0c gw zlible, and the source is moving away from us, the color of the light appears to us to be :s sh)4b.mf1d;90x6 mzxg wl x(jclgcshifted toward the

  The cosmic background radiation corresponds to a tempera4,c * va. /8pp ryj7l*t1 bczbsfpi-r6u,igckture of about

  The Sun has apparent brightness 8r)jlngl; v*wat 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 n91a.*dm vglz,. 1ya pwpgmcn p)lx6 .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 aiipgcph- sk q86u(.7r ei 7mbi701x/zjimr ,m 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 ha65so 7 dqi w/;ha;lq.pqgcez0 s a 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 Proxima Centauri, which is Earth's 7 lh e-bz(3tp)i7gjvdnearest star at 4.3 eg zl)h 7- 7vdp(bjti3ly?

  The apparent brightness of a star sxn/0jn :me a7is $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the uashp +-g+r :uz urf8h3niverse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate 3-r agu rs +8fhhpuz+:the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far t:e91 tj 2ih*t da)ty hova9m*away is it from a1:tt9 jvmta* h tody9e2)i*hus?

  Estimate the speed ofmb/ca30ml -pw a galaxy that is 10 billion light-years away.

  Estimate the observe3r , yu:(ysfxfxhu*; otst5c)l yty23d wavelength for the 656 nm line in the spectrum of a star which is 100 million lt ,f3y r2xhy*y;5(yul3:f utc) tso xsight-years from us.

  About 1 ms after the Big Bang, the temperature of the u gr6;vcx vutcr91s.;9 .ym mlbniverse was about 1013 K. Whatvmmc.1 ybg.6u t 9;v9xrcl; sr energy (in eV) does this correspond to?