The appearance of the great rangf9cw 1o 4juihi,ggc88 l0pj2 pe of brightness among stars is due to

  The absolute luminosity fon3a 2pq25rp bsr most stars depends on the

  Four different main-sequji7m7u, rm cos:82xgq ence stars are colored blue, orange, red, and yellow. What is their rank fm:,7sgj2 m x8cu oqi7rrom coolest to hottest?

  A Hertzsprung-Russell diagram shows j+f hf6s)lpz8* lxbxz p3o 1j/cpj69gstars on a plot of

  A white dwarf star with a mass equal to that of the Sun ing(y:jc ikuej; cr8 0 a;fn20xs about the size of

  The Chandrasekhar limit-;r86zazljn f of stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is la8;-j zf6r nzM, about

  Supernovas are thought to always regtfy;kg pdpm-: b +7+at4hn .+kv+vsd sult in

  Black holes

  Pulsars are rapidly spinnic *x x(e-xvk tpjqk1/0ng

State Einstein's principle of equiv/lknf y1m .,dvalence.

  The Schwarzschild radius of a black hole is that raete/y;abq+m kf9 81p2p lg x- yq8wd3pdial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzs/d -xt2km;9e81flbpaqq 8 3gy+eywppchild 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 wave diu:c egg lsa.;5wy6*length in the visible, and the source is moving away from us, the color of the light appears to us to be shiys lw cga.u;:6e*5dgifted toward the

  The cosmic background radiation correi1i3g;xb+r l )fime 6nsponds to a temperature of about

  The Sun has apparent brightnf0w.p-p/tex m n(lpr z)i/ ma5ess 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 ea n,te8(.a2xul1b kicqual 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 e vbcirkm us/ ,gun0y1pd/9/8e+ p6era 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 mea8 z/ hfbap5zx: n,a+bgn 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, whik7z,2q tzf g:lch is Earth's nearest star at 4.3 l2l7qft :zzk ,gy?

  The apparent brightness ob* 6nd6 xizum,hib*nm72 2te so(/hfdf 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 univhtrg+ s 3cvhj8r47/g zerse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in yearr48c7g s+h3/z jrtvh gs.

  If a galaxy is moving away from us at 1.0% of the speed of light, howj ye1kr5 3ksc4 far away is3rse c1kjky 54 it from us?

  Estimate the speed of a galaxy that is 10 bimtnj h -i495vollion light-years away.

  Estimate the observed wavelength for the 656 nm line in *.c,fsrav 7qathe spectrum of a star which is 100,c .*7 vasfqar million light-years from us.

  About 1 ms after the Big Bang, the temperatur5g oh6ik1t.8tdx v2:bbps2 hk e of the universe was about 1013 K. Whaxsk 2g6tp o hkht1d 5i2.bbv:8t energy (in eV) does this correspond to?