The appearance of the great range of brightnnlt209*by n bdop0-ncyt32b w ess among stars is due to

  The absolute luminosity for most stars depends8y;9x1ah zghi7 pa :sxev/:mk on the

  Four different main-sequence stars are inciw2 xkfvn-)0kp .: colored blue, orange, red, and yellow. What is their rank from coolest 2: kicni0)wkpn x v.f-to hottest?

  A Hertzsprung-Russell diagram shows star+doj7+r aeu3o s on a plot of

  A white dwarf star with a mass equal to that of the Sun is a 7x54 h+l sg7n+z qtxt8tja,d iz55lsebout the size of

  The Chandrasekhar limit of stellar mass (below which a s fk p9mizo)7nh4ix3;qx1:gdy tar will collapse into a white dwarf) is, if the mass 4:mi)k39 f g7 di1yhnox;p qxzof our Sun is M, about

  Supernovas are thoughtz yj ,2xrs-m27ojbx8)wafu d8 to always result in

  Black holes

  Pulsars are rapidly spinno 5cr05ctknde)-mn 6 kal(4zking

State Einstein's principle of equiva rz :syyp f8w,dy1;w,alence.

  The Schwarzschild radius of a black hoq3(2gf;k2;+u:x5dfcx euo jkf 1 aptg le is 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 rela xo2(5q ff+d;g31a ;f2u k:jgpextkuc tivity 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 visible, nice ue5e4;zg1u qw3/ and the source is/we4cee qni51g3 u zu; moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background raudq u s3l.kzd1bb /5n4diation corresponds to a temperature of about

  The Sun has apparent brightness at):at*ss.viqpz wsot5 oxp 40. 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 eq;e 2tk,m yn 5;m/gxeo8erhnp2 ual 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 au-bq wxe:83vjg x6*mf 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 hau5y(hd:l zq6 5ckoo y+xl+x/us 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 angle for v2aszn :d( 0dzProxima Centauri, which is Earth's nearest star at 4.3vdd (z 0:n2zsa ly?

  The apparent brightness of a sg/n(xemq8vhf uc4m-.tar 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 thvqi,geb)3pc(,rl q v3 e approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the gvp,l3r ,(3 q)ecibqv age of the universe, in years.

  If a galaxy is moving 1616kksuuogz) xv) gdaway from us at 1.0% of the speed of light, how far away is it fromxkzs k ug1)1v 6)udo6g us?

  Estimate the speed of a galaxy that is 10 billion l 9f5x 7 jlvdhen*fvn :08v8ruuight-years away.

  Estimate the observed wavelength 7:1ar(jw3 1e(vxukqg 5gxqzkfor the 656 nm line in the spectrum of a star which is 100 million li a ( w5e3:1 xj7qkzvgx1ukg(qrght-years from us.

  About 1 ms after the Big Bang, the temperat 2jg( (-xav(froz en5bure of the universe was about 1013 K. What energy (in eV) does this o rf(bxgnav z(e52j-( correspond to?