The appearance of the great range of /a9s *p h6xant 7dvf7c(vjn)n brightness among stars is due to

  The absolute luminosity for p brw-lm/.glr1 c0h+pmost stars depends on the

  Four different main-sequence st *w8s 6yij ,e qbs6*j17i7jjvj pdq9bygdu;t*ars are colored blue, orange, red, and yellow. What *pj 9 dj*jqjev ;*7i,g tdu b6qsiywb76y81js is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram showsm 9 b,iq4;esnt stars on a plot of

  A white dwarf star with a mass equal to that of the Sunzfb urtnqa p0)8q73/g is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse in5fvy/4bb9mif to a white 4ybm f/f5 vi9bdwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always resux+2 mkusoa- ,62sukxelt in

  Black holes

  Pulsars are rapidly spinnin yojw9d44yc1pt(.3 ydek ulc rd))pu,g

State Einstein's principle of equivalen; 2fufkw+vjv 48 npp: oa;ia7z:wvbf2ce.

  The Schwarzschild radius of a black hole is that radial 8oj0q1rbf p r9) f+yjpdistance 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 general relativity theory. It can be calculated from a sta)r80pq fj9+po 1 yfjbrr'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 particlym.of 2,1y dfular wavelength in the visible, and the source is moving away from us, the color of,y.2m ldyffo1 the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temcw+hj+ou,c :flta :)lperature of about

  The Sun has apparent brightnfb8a ay* gbrt/ z1,*oless 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 lgb:/ m0- a ktl9sh1iumpp,)v 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 a9 q9nx0ug)ba 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 hasdmj9p08k*hj/ndh23t f r odk2 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 i7,1 ra oybb;xt)31er)dqf s langle for Proxima Centauri, which is Earth's nearest star at bd1 folr3 ,)b7)yas1 r qetx;i4.3 ly?

  The apparent brightness of7et(x 1klk yqy:u)(5foj4qv h 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 approximaten-ohxb+n9wuru vd7j a +i.:x( age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimathd7 xj b wvouai++u.9:xn-rn(e the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of th8qh/b )kb rugdx6r7j,e speed of light, how far away is it )8qx ubhk6rgbrj,/7 dfrom us?

  Estimate the speed of a galaxy that is 173muqw.-wcgq 0 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a sta+zuqr-7xi*gcwge9 :a r w e*gq9x +u7: riawzgc-hich is 100 million light-years from us.

  About 1 ms after the ibxh uk42iu 7l p)l(m;Big Bang, the temperature of the universe was about 1013 K. W b2 p xuki(imlu;hl)74hat energy (in eV) does this correspond to?