The appearance of the great range of brightness among stars is .e+cp ,umomab o8d63 wdue to

  The absolute luminos8uba y/ah:+mp6 e klf *ac09lsity for most stars depends on the

  Four different main-sequence st rs h7;e7wdk xam(l)yxl 6b:v6ars are colored blue, orange, red, and yellow. What iv;6hylre )a:6(m sx xwk77dlbs their rank from coolest to hottest?

  A Hertzsprung-Russell dia z5kqrrm0b:uf. t9d /pgram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about t:fasqm7 0ppqb8r jg; +he size of

  The Chandrasekhar limit of stellar mass (below whh nar.ebb+g*l9 nd 3b1ich a star will collapse into a white dwarf) is, if the mass of our Sun is M, bearb1 9dl*3b.gn+n habout

  Supernovas are thoug:ca pr2-fjmqh :k(es 3ht to always result in

  Black holes

  Pulsars are rapidly spi4e pg(2dc -dexhx;gs- nning

State Einstein's pribc8 *2 *urui(fsbq0x 9t0u ptdnciple of equivalence.

  The Schwarzschild radius of a black hole is that radial distan1d0zotc/w w b;xqrrub 5)v59 bce 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 cax;q/ r55dwrw bozt 90 )bbucv1n 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 particulyq0 8+axn tyr phz/:tb (r:j(3qww :aiar wavelength in the visible, and the source is moving away from us, thw+t(3ywjyiqt p x0z/ hr b:q:8 (ar:ane color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperatures: (a (k++luf0do8qj byke8am of about

  The Sun has apparent brightness at 6p4w * bbuut.lEarth ($1.5 \times 10^{8} \; km$ 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 b:pejy u6;je id487,7nljj t9ddc5bw 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 mg1 6pwhlk+ e2j;rh7ntean 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 radius of *- 7yvrk5p7soygwvk duv*52 n$1.5 \times 10^{8} \; km$. 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 -fj19yd va9hyis Earth's nearest star at f99-1adjhvyy 4.3 ly?

  The apparent brightness of a star n*: hq7 q13ny.mdo2uhq kgvh n4j 44ybis $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universe is 1/H, where H isit 4(.js eyvy hlj*s wa0;a8s/ the Hubble constant.s0 ;(. /iwesjyvsjl4ay*tah 8 Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at,by brjk-k:;x1 e,nv n 1.0% of the speed of light, how far away is it frovj-eb1xbn,: r,y ;nkkm us?

  Estimate the speed of a galaxy that is 10 biy e p6g m88f)lc*bky4pllion light-years away.

  Estimate the observed wavel.j a dl/ ud5*-1qndgizength for the 656 nm line in the spectrum of a star which is 100 million light-years fr*adl-q5dudjgi. z /n1om us.

  About 1 ms after the Big Bang, the temperature of the universe was r(0ut7coam,b iz2o.n about 1013 K. What energy (in eV) does this correspond ta m, .0crbiu7tzno(o2o?