The appearance of the great range ohx2 :d qfw;st2hd +db/f brightness among stars is due to

  The absolute luminosity for most stars depends on thg k9e)4tmms ;mwjdq*2e

  Four different main-sequenct tk0dpy)z-4 w6gb4zu n3 7zewe stars are colored blue, orange, red, and yellow. What izu) nkzwpbe-z40473yw td6gt s their rank from coolest to hottest?

  A Hertzsprung-Russell diagram s )ygtls 2-mv;n,0gktx hows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the s8q5qiuipb4s z 16ww4 zize of

  The Chandrasekhar limit of stellar mass (below which a star will collaps:e/x fep3 zxg5e into a white dz3x xgfe/p 5:ewarf) is, if the mass of our Sun is M, about

  Supernovas are thought to 6ifqe)pb7 qq d.qd-8/hl pq *walways result in

  Black holes

  Pulsars are rapidly spinningd v (2u3)kycsl1 sydw4rl )f6l

State Einstein's principle of equivalenct o7-/6-chdumks k 9ece.

  The Schwarzschild radiusgvq56wyq.rsgsb 2); h of a black hole is that radial distance from the center of a sphere within which not even light can escape. It was first dsqg6)g yhrs; 5q.2vw biscovered 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 waveleng1d0(z whnu ) +xee5 9ade )g3sb;auawfe9-oc ith in the visible, and the source is moving away from us, the color of the light app9beee c zuxdg5(aaow + ef31u-ih); 0snwd 9a)ears to us to be shifted toward the

  The cosmic background radiation corresponds to a tempe5tfxh41k d)a vrature of about

  The Sun has apparent br+tw yc5swl/47z pl ) /yc7qnsdightness 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 Sunk nhj;h24rzl.* enqq 2 ($1.5 \times 10^{8} \; km$ 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 has2 gcu tm()2hhv 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 km?

  The Earth's orbit has a mean radi..upo+ dq2fk sus 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 Eayi q(81(eczjvh )g0h arth's nearest star at gi0jhzc (v8 qa(hy)e1 4.3 ly?

  The apparent brightneszaey6 7af8 sem(;9 x.xkncy*ps 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 universe is 1/Hsg ,gh;*6b) ot 1bwyti, where H is the Hubble conw *,yo)tst6;bbi1h ggstant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us a0 kat7e 6tq ,j/qqgj+gt 1.0% of the speed of light, how far away is it from ge6 q0g qj/+t7kj,tqaus?

  Estimate the speed of a galaxy that is 10 billion light-ynlmdq +ed.bh.pft/,;( 7ebi nears away.

  Estimate the observed wavelength for the 656 np.q;wjvfp, p5 v.195 .cfb qqii pfizl 8i50ysm line in the spectrum of a star which is 100 million light-years from us5,b.1p..fcsi 5ljpqiy q;f0p58 qp zf 9wi viv.

  About 1 ms after the Big Bang, the temperature of the universe was abou*640luce xxh pt 1013 K. What energy (in eV) does this correspond x4epclh *0x6u to?