The appearance of the great range+*a ec9v rp.opq +q1: fwnaop2 of brightness among stars is due to

  The absolute luminosity for most stars depend2w-i i+pxx/ 5 v8ibszps on the

  Four different main-sequence stars are colored blue, orange, redhsmjb /li8; q:v-d6 as, and yellow. What is their rank from coolest to hottest? 6m-bash; ls:v8qj/di

  A Hertzsprung-Russell diagram shows stars on a plot oli,u s8c4ux ;cw)(ytdf

  A white dwarf star with a mass equal to that of the Sun is about thl3gb 8g .fi2l r0n 4*a7wlxxjte size of

  The Chandrasekhar limit o1( oe6k;qak:bqyu +k lxir;3 of stellar mass (below which a star will collapse into a white dw xeay36k;;oq uq:+kk1ir(o blarf) is, if the mass of our Sun is M, about

  Supernovas are thougkla / ay/:zl5mzrhcivuhu:6a *n3u - kddx5+ 8ht to always result in

  Black holes

  Pulsars are rapidly sj9hcye6 6m rk1afw-* ay, l9ry3d: gwlpinning

State Einstein's principle ofst e7)b7odm,s equivalence.

  The Schwarzschild radius of a black hole is that radial distj 4w.9lvu*c p g6uf00fxzl d-cance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his gepw gjdxu00c cvlfz4u*9. l- f6neral 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 4p)lhuu413b-b mxwrvparticular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shifted toward thebx4431pbumrwu)v lh-

  The cosmic background zg877t3w qh kzradiation corresponds to a temperature of about

  The Sun has apparent brightness at Earth (x(:hmj(t bb(0dw+,q w 4/ ucems.e adl$1.5 \times 10^{8} \; km$ 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 equ,vr:/ d 1vsul0gk1kb60 g ktjqal 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 m7oq2/o iuolv)jyhls/8w4 p;bean 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 mean l-/8-mxmh7u7 tx siwmradius 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 el5xl; d.f hi5Earth's nearest star at ;e.l i5hfxl d54.3 ly?

  The apparent brightness of a star is glt ;wau;v6n2$1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universe izc/ksg a0uk)9 b)(d vqs 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, ib zkcd9vg(a/q u k))s0n years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far away j(cyh ;9(rpsm uq a7f1is it 71(hc(;yr9fq jaumspfrom us?

  Estimate the speed oamvf z,)-wr7xzn 0q ubr/3z9ef a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line i9l, bglccn q 78dwq7eg :7ibk5n the spectrum of a star which is 100 million light-:d ebcgq5b ilq8wckl77 79,ng years from us.

  About 1 ms after the Big Bang, the temperature of the universe was b aovzqs7z3h9 mlo +.6about 1013 K. Whaqma9o h z +s7lbo6zv.3t energy (in eV) does this correspond to?