The appearance of the great range of brig h:yee 4ow-zt5j0/yhgx ;gthe5 n5-nehtness among stars is due to

  The absolute luminosity for most stars d8wg+axwe,pl c2;kd 7 sepends on the

  Four different main-sequence stars are colored blue, orange, red, and ye3ou hn2 prk*x*llow. What is their rank from coolest txhkn32 *puro* o hottest?

  A Hertzsprung-Russell diagram shows stars on a plot g o sm,eoi/.b(of

  A white dwarf star with a ma :dq -d rt(sfw,x/5bqfss equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapsean;hpl/7u7t h into a white dwarf) is, if the mass of our Sun is M, abou/uh7t7p;nhla t

  Supernovas are thought to alv 3q1rer6elc:ways result in

  Black holes

  Pulsars are rapidly spinningk;bl.q 861id yy/m b u t*ohi5nk3qbk5

State Einstein's princii xqm(-+ x/bey27 qkcjple of equivalence.

  The Schwarzschild radius of a black hole is that radial disom i ;bh1(tjp0tance 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 calcu;b01ht o (mpjilated 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 0l msk2wt.++k c7r wvcvisible, and the source is moving away from us, the color of the light appears to us scvc +kkm7+t2w0wr.lto be shifted toward the

  The cosmic background radiation corresponds to e i-rs*yzb+6j a temperature of about

  The Sun has apparent br 7xua nptc.aypav :0)lb3*c+mightness 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 to thlu7 bl 4dr3d4uat 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 oiow0q2jd fv 89f $1.5 \times 10^{8} \; km$. 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 sz6iinlhe k,o*5b. *g 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 Ea6i,y e ih-c4gqrth's nearest star at 4.6y4,hg iqe-i c3 ly?

  The apparent brightness of a st:cw7u aee *v;far 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 approximate x9v -e 4ex.npnage of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, inexev n-.4px9n years.

  If a galaxy is moving away from uw-gub 9wr;xh34 wx2kms at 1.0% of the speed of light, how far away is iu4 m9hrk-3wbg xww2 ;xt from us?

  Estimate the speed of a galaxy thalyj+jkr a;qf,: ,f8rrt is 10 billion light-years away.

  Estimate the observed wavelxep w+*-evfs4.:t c eqength for the 656 nm line in the spectrum of a star which is 100 millionfvts 4c*w:e. ep+ xeq- light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe wa 5j 5dvdq3qnoy6ybnx8 2teb5 *s about 1013 K. What energy (in eV) does this corres6*3 ydtnebxj5nybv8q5d5o q 2pond to?