The appearance of the.baz:8r c5 v1xw: o8jn cpbwo0 great range of brightness among stars is due to

  The absolute luminosity f v*h(w yl3.ij;-t-q3ginf xmuor most stars depends on the

  Four different main-sequence stars are color yds5 s2)m85z;cz t*cjl5 hj)+rtvu weed blue, orange, red, and yellow. What is their rank froes 5; cj+z)ljsur dvtt*52z h5 8cym)wm coolest to hottest?

  A Hertzsprung-Russell diagram shows stars9/h8wd0 73o.g q/xrrnkq fe cz br,i4t:jg0rl on a plot of

  A white dwarf star with a 0e wz51mwq 8*v7xn bcgmass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar*4 aam5.zu mnj/ k0fnfk;njz+efc6w 4 mass (below which a star will collapse into a white dwarf) is, if the m +4m6 j0f ;nmknnf4uw.ze*kc5 fa/a zjass of our Sun is M, about

  Supernovas are thought to hxh)a wup.ao8drs: i* h6 hj05always result in

  Black holes

  Pulsars are rapidly spit 8vq+rbafbk no11e j6.ru-;j 29ldgsnning

State Einstein's principle of equivalence.z-ufhw0ho;k,nlb.ju( n ikv. s(fls0ir48 +g

  The Schwarzschild radius of a black hole p1ez fdt*2r f(k+ w:fbasuw), is that radial distance from the center of a sphere within which u(w1a,zbs*)k ed f2:tfrpwf + 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 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 pzylq+gg5/srq8 1tkpcyj0bl-0 gy9;c articular wavelength in the visible, and the source is moving away from us, the color of the light appears to kccys0 l5qbj py;gyz9-g8/0 qr gtl1+ us to be shifted toward the

  The cosmic background radiation corresponds to a temperao5y :kco ;phg6 f/zx4lture of about

  The Sun has apparent brightness at Earth 1 s a(ohoobf (s;l7ut9:lu*qs($1.5 \times 10^{8} \; km$ 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 luminosity2aq1 + ypw;cx ce-sh/x equal 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 mean r g (v(jdmsbq0l n.4ke/adius 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 hasbz0f).-r-d 4ymuo., lem ojty 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 ack43h9 h -r y.bw6ntdpngle for Proxima Centauri, which is Earth's nearest star at 4.3y6.3t dhph r9nbcwk 4- ly?

  The apparent brightness of a star ie1hw ;39:e*odh ,go cgwmre0ys $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approx6dvvubw c :v+;imate age of the universe is 1/H, where H is the Hubble constant. Takbvwcdu 6;:v+v ing H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of tn2(togloq+ r )he speed of light, how far away is it from gr ton2q+o)l(us?

  Estimate the speed of a galaxy that is 10 billion light-years avz;bqr *g-x(away.

  Estimate the observex0na 6klbwhmt- j lxx:33 r.q4d wavelength for the 656 nm line in the spectrum of a star which is 100 million lilj. 3-xt3m6 hkxw4a: lqxrn0bght-years from us.

  About 1 ms after the Big Bang, f5rj; 7sum6*t-joxmo i4twl9 c5tpe +7 4smhz the temperature of the universe was about 1013 K. What energy (in eV) does this cme hrw+4stijtpo9 ; *z6o ct4mfjsx7lu575m -orrespond to?