The appearance of the great range of brightness among szjo bn-w1t-5u tars is due to

  The absolute luminosity for most star+, sppxkb 2,mxs depends on the

  Four different main-sequence staqy lqd8m7 p8r7a5ichr(ui8g -rs are colored blue, orange, red, and yellow. What is their rank from coolest t8rp8ig7dlqh q-cau 8 ( ryi7m5o hottest?

  A Hertzsprung-Russell diagram shows stars on a plot 6p9pcu) xsmvo bj8a:2 of

  A white dwarf star with a1.k usa6newm )eco+olte7,,a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below weyo (g:bc6*mpxl7tt , hich a star will collapse into a white dwarf) is, if the mass of our Sun is Mymt(*l6 7o :gcxbet ,p, about

  Supernovas are thought to. mgv 6zyfca r7rh+z31 always result in

  Black holes

  Pulsars are rapidly spinnin)/zqtuqr3tt9s6t.nw9j ui 1 ug

State Einstein's pri28:)hl * mpc wlkrgph( 1eq;8px0vwvtnciple of equivalence.

  The Schwarzschild radius of a black hole is po0nr/.(ec op that radial distance 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 e0c.(orpon /prelativity 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 in the vis)4gfninl -y :ilq8 m(gible, and the source is moving away from us, the color:4g8)l( qmyli ngfn-i of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to6v0k d/ uw+ztp a temperature of about

  The Sun has apparent brightness a5+/ by+u7l s;4udc id veenx)n+y+blft 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 luminosx:weukk7 0wd g:f1bcpd/ : s)oity 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 radius of ccv ym+;zotl x gp;6vi66(z:v$1.5 \times 10^{8} \; km$. 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 mtu*7am na0g9re n s/,eean 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 Eak,n; -q6t ukwkrth's nearest star at 4wku6n-kt; ,qk.3 ly?

  The apparent brightness of a star isplyfhfu, t1 b;89+ys ia a5or4 $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the apprdlo8fn d79kjt */ hlhi1o a)l6-f hgt*oximate age of the universe is 1/H, where H is the Hubble constant f-61*n of)oghhliljdh7 /*t9t8adlk . Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is movingvm3g;w/x r xn-;igkov d9: jw9 away from us at 1.0% of the speed of light, how far away is it from ngm-3/9 ww;o:vxg ;jri x9v dkus?

  Estimate the speed of a galaxy that is 10 billion light-years jo,x d1ycd,)mo/r/kbaway.

  Estimate the observed wavelength for the 656 nm line in the ;o-o8 ijlbt b*n ozk3n6:de5a spectrum of a star which is 10ai 6n:;-5bzooe8*b3 tlnod jk0 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the u7 5uiunigv /1jniverse was about 1013 K. What energy (in eV) does this correspo1ni 7v/ jugui5nd to?