The appearance of the great r.qzem9xtp bpw07fp ,*m t*f;x k6m of*ange of brightness among stars is due to

  The absolute luminosi kkp 7dw;3za hkg.+qoryxn8-; al5)hpty for most stars depends on the

  Four different main-sequence stars are colored blue, or1c nivq5gjcsm on 4p6 9j +p97l-iqm(tange, red, and yellow. What is their rank-1ilp 7 +(vn9m4spn9tj 5i6gqjc comq from coolest to hottest?

  A Hertzsprung-Russell diagram shon.(4 +fxgsu4dwdp zs 1ws stars on a plot of

  A white dwarf star with a mas +jg)u1 *jdq toouv;v4s equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star wi f**/q:ucms: lpp jegkb;;j 6oll collapse into a white dwarf) is, if the mass of*ps6 fjlpmj:/o: bg ;uqc;*ek our Sun is M, about

  Supernovas are thought to always result 01 nmn0 c(hkw)o2wsumin

  Black holes

  Pulsars are rapidly spcmt/ea(l4b m1inning

State Einstein's princi; g 6c:mcq+huuqroq29ple of equivalence.

  The Schwarzschild radius of a black hole is that radial disb;k06ebw x ng;ebm4way)+rp0tance from the center o 040eea; pw;ym gx) nw6bkbbr+f 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 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 emitgjh 8m x4buj99*hld-2)aa ovxs light of a particular wavelength in the visible, and the source is moving away from us, the color of the ligx 4j*-x2o jm dv9gh89lau a)hbht appears to us to be shifted toward the

  The cosmic background ratgrro.):f 5 9tecm qe4diation corresponds to a temperature of about

  The Sun has apparent brightness 18i a*4zvu ldxat 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 lumiu79evxplmksjui6 p mm3; b345nosity 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 rae 18-tv;dnpif6fa)6 x z*teutdius 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 a9rb5i ulxg b)u ktznf 8+-i33y 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, whu2z;az yz-m,nx vz 5y:ich is Earth's nearest star at 4nmz;y2u,zy xz5 z-:a v.3 ly?

  The apparent brightness of a star.rurijtq 6 2(e9n8 ldf 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 slierp 0(9k-ethe universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estiseek(p- 9ir0l mate the age of the universe, in years.

  If a galaxy is moving away from u s1rz hz(qy7:as at 1.0% of the speed of light, how far away is qyz r (7as1z:hit from us?

  Estimate the speed of a galaxy th8omov y/ry*(pe65 xfdat is 10 billion light-years away.

  Estimate the observed wavelength fvm 2+(ydwt9 vdor the 656 nm line in the spectrum of a star which isddyvm +9(wtv2 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013t04iu s91lhxf K. Whasf09lht 4ux1 it energy (in eV) does this correspond to?