The appearance of the great range of brightness among stars 9xz1 i6yotnf2,ano m /*v,l wdis due to

  The absolute luminosity fo6 cld)urx1js y:qsmxi(.q c45r most stars depends on the

  Four different main-seque;gro6 coq;9y snce stars are colored blue, orange, red, and yellow. What is their rank fr c;9 qro6sy;goom coolest to hottest?

  A Hertzsprung-Russell diag;rgok ik o+ (va2xsk2 4ctm.ub9b3p1aram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun iknm7e b)1xnj 2s about the size of

  The Chandrasekhar limit of stellar maj; ya rlhxtg;8omq8))ss (below which a star will collapse into a white dwarf) is, if the magq ajom xh;y l)rt)8;8ss of our Sun is M, about

  Supernovas are thought to alwaf1cs */bab3fiys result in

  Black holes

  Pulsars are rapidly s+qb4 ; /oxnvh hf7lra/pinning

State Einstein's principle of equivale6bac dui8n*x 4cke*+ rnce.

  The Schwarzschild radius of a black hole is tfcbm1es eeh6.xs5 ;: ff+5v achat radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwffb xc;c f+hm5a6e5es v1.:e sarzschild 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 /r.g4 ,e npvygp( gz*jin the visible, and the source is moving away from us, the color ngzv gp/ g* ,y4p.j(erof the light appears to us to be shifted toward the

  The cosmic background radiation correspondi6-zf t g/f4afek2,g 3 de,fles to a temperature of about

  The Sun has apparent b:*ikysjc s2:f z3aoej+9xmv;rightness 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 eq,o;y ,nmn ( xelu/)lfoual 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 4iq1ebwdo a90 r d*.w8k awle+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 rild:49l)7x,f4ku8 dhspuod 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 angle for Proxima Centauri, which is Earth' ld.;i,m 4uqq9 noca/ b1(euxbs nearest star at 4.3 lyoacibq 4,e (/9u l; x.udbm1qn?

  The apparent brightness of a star isjgj1 )dl7 4esj $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of thi.;lg -czh tu 8rcz8b,e universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.u hzcr ,;izc.l88 gt-b

  If a galaxy is moving away from us at c8abyddg42p ,1.0% of the speed of light, how far away is it from c 28,b4dd yapgus?

  Estimate the speed of a galaxy that is 10 billion lg8kmrg k: de3 9nytq2+ight-years away.

  Estimate the observed wavelength for the 656 nm line nqkl c rt6)v+c 0kx k*(atnf,5in the spectrum of a star which is 100 million light- k6*nx avkl )tn,k(cc5ft 0qr+years from us.

  About 1 ms after the Big Bang, the temperature of the universe w y3h8dc5ljoj3 as about 1013 K.3j8c3ldjho5y What energy (in eV) does this correspond to?