The appearance of the great range of b0evnd q+ o*5jerightness among stars is due to

  The absolute luminosity for most l3y2f2j7 qfuwstars depends on the

  Four different main-sequence stars are colored blue, orr2tumz q3m9v3 )qgh7-z)ey ;40 d-xayedlra xange, red, and yellow. What is thy 7y-- mxa l)m ta3qz dr0v4e h3du92rz;gx)eqeir rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a2wnt ox9jbz/0 plot of

  A white dwarf star with a mass equal to that of the Sun is abourcq -o7 cts7f5t the size of

  The Chandrasekhar limit of stellar mass (below which a star yrow ;n4v5.4ns/v x n+(wsmli will collapse into a white dwarf) is, if the m(x r4isow4 nv;+s/w ny n5v.mlass of our Sun is M, about

  Supernovas are thought to alwas oeih p6)2voky3(q)mys result in

  Black holes

  Pulsars are rapidly spingh28*pqg qkqx *n58bbning

State Einstein's principle offa epp yx wq47n9 twd9q22a6u( equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cente r pn g.j5h9p.tez1 3r/d cd,phid4ej7r of a sphere within which not even light can escape. It was first discoveredtc, d drpp9.rhd3e/ .e71z 4ni5jhj gp 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 wavelength in the k+- i rs.mdl1k48ih v3f1qjuzvisible, and the source is moving away from us, the color of the light appears to us to be shifted tow3d8lz vk jhk urf- +q1.4iim1sard the

  The cosmic background radiation corresponds to a tem ygrmp*frw* rp48+g,o c8xj d(hr)bx- p e*f1eperature of about

  The Sun has apparentnw tm1ark*q z)q.0 :kk brightness 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 tnvtcx:vg qmr*w7,3s q l*+x9 rdovr0 )hat 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 radius of y ex1 h;q75qg/x,esb4gj*l id $1.5 \times 10^{8} \; km$. 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 radius ofg-bc wx0l+)jc $1.5 \times 10^{8} \; km$. 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 un 1j 5 bs a.jlh;3u;v,wrb.ezis Earth's nearest star at surejbb3 1;.n.a l;jh5vwu,z4.3 ly?

  The apparent brightness of a star i;5bnvh ch:lt5g:z3 aes $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age o4fck4j4ewda 4f the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimatefk w4e4cjad44 the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed i2/g 4h ipvic.jcmwb.*e o-t4of light, how far away is it from c*vh24.mp.b o tj 4i/ewi-cgius?

  Estimate the speed of a galaxy that is 1 4 5wcpktn*3op0 billion light-years away.

  Estimate the observed wavelength for the 656 nm ae+b8fwu vya--2 c5hs line in the spectrum of a star which is 100 million light-years vshy+f 8uaa 5c2 -w-ebfrom us.

  About 1 ms after the Big Ba*-.f fdr; naoqng, the temperature of the universe was about 1013 K. What ener;*.dfq ro-fnagy (in eV) does this correspond to?