The appearance of the great range of brightness amon ;o)jb9o;+ hilxnyn rxy/w us.n35cw4g stars is due to

  The absolute luminosity for mostwsc*u nt7 ,,rd stars depends on the

  Four different main-sequence stars are colored blue, orange, red, ayo cj0jg+kz: )12z psxnd yellow. Whatk2:z 01) cyjp+xzsjgo is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plo t.m+p:p sd2ayt of

  A white dwarf star with a mass equal to that of the Sun iuywish*6 f g1/s about the size of

  The Chandrasekhar limit of s 78q7gvlqn x.t; .4mcer7wkzwtellar mass (below which a star will collapse into a white dwarf) is, if the mass of our S7 cn wewq x4 v7g;lm78.krqt.zun is M, about

  Supernovas are thought to always result v ,jf3aqpgzp2 w0*wq )in

  Black holes

  Pulsars are rapidly rr9by ,zp2w ytl5y(bfb;p(z 5spinning

State Einstein's prin7aul1/x )ao qaazge2:+c p kima4b h))ciple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cend omkr s7xl 2/nliqg,+8dn -5hter 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 m-sxl nlg +rq/ 7in28h,d5okdcan 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 inz-idd t7;; k.n x7vtit the visible, and the source is moving away from us, the color of.zk-d7 ; tni7v;tti xd the light appears to us to be shifted toward the

  The cosmic background radh )ri3sn:prdclo:x 5) iation corresponds to a temperature of about

  The Sun has apparent brightnesu e *7 n,vuz1,*lawxyks 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 Sun58y uz.vwgtlq8b;10;sv)xmr qr *gwf ($1.5 \times 10^{8} \; km$ 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 /g/ r rnpiwdt832c;1j6sdclvf gy r30 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 haf z:i8uphqo )h7sjww4pmi 678zp- )yzs 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 angleabfyx,n n-9n +lq *. llm2cc6a for Proxima Centauri, which is Earth's nearest star at 4lncnm .+ *,bacl -n2q6lfxa 9y.3 ly?

  The apparent brightness of a 3gz 0o0s f/jm1s-(k/j ccvsy bstar 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/ebrq4)k cbo0(bmu1r 3-n xe4mu lq.*oH, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in ye(0cuoqk1e rr4nm4le.bbm x)3o q*b-u ars.

  If a galaxy is moving away. ,q*po dvzmbazm +e/. from us at 1.0% of the speed of light, how far away is it from u/+bz q,domz.em*p v a.s?

  Estimate the speed of a galaxy that is 10 billiomyf3gk,q +r ss1eli0 ):py3 shn light-years away.

  Estimate the observed wavelength for the 656 nm line in the2y 0 h+ribzsua-u125 ax-a0fw rwj+s l spectrum of a star which is 100 million light-years froa0h0wb l sw2 jrau2f+ r+ x1zsa-5iuy-m us.

  About 1 ms after the Bisci-23v8d+z mq ,j2kk(f c)kb3tge).zbjnyxg Bang, the temperature of the universe was about 1013 K. What energy (in eV) does this 8-z c.j2 3kz) i kjc x,bnbt2 3dmvge+f)yq(skcorrespond to?