The appearance of the great range of brightness amongmuxf(xm d 9ioi i i15dv;*,ah4 stars is due to

  The absolute luminosity for most stars dependzd+harh 7a5t- i tqr34s on the

  Four different main-sequence stars are col7 fz8qsen,x2 cored blue, orange, red, and yellow. What is their rank from coolest to hottest,szcxf2 nqe 78?

  A Hertzsprung-Russell diagram shows stars on a p)j .dsgnlkvm4ry.v3 cjc6,o 9lot of

  A white dwarf star with a mass equal to that of the Sun is about the size o8+kgif/* t/l5tr *)t hpkrafof

  The Chandrasekhar limit of stellar mass (below which a star will clfr0:6lnkgq2 ni-x p7/bg49+v h0hx tkeyc 0zollapse into a white dwr ig/k6ellvhhc0+k097-2g 4znfn 0 yp qtx bx:arf) is, if the mass of our Sun is M, about

  Supernovas are thought to alwaysr0txh ;f 67rulk/nok1 result in

  Black holes

  Pulsars are rapidly spina g.t o/3:)gtythq5x3oy) mtuning

State Einstein's princbp9 +dlv;)xdx(la v-diple of equivalence.

  The Schwarzschild radius of a black hole is that radial dist-n)iky (qgcj;p*uv; izg( w+f ance 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 genyifq-g)j kpn cu ( wi;v*(+g;zeral 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 paxe)w2)ma v3gm b:9 ;g vn7nendrticular wavelength in the visible, and the source is moeg:9w2xmmnan 37e bdvg;)v )n ving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corrq8rmw pp3n:x3o s8 plxmd3*7xesponds to a temperature of about

  The Sun has apparent brightnessp,qc x(wdt bf u3t ;m(v/7tms8 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 t srqd+ vu.tg,2q+/urmhat 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 mev vd mpyi; 1*8x*xodf.an 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 radikmwj /c)xbciu p(y70q z+) n/cus 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 Cent+wv t1ovpx6;+rl ja7f auri, which is Earth's nearest star at 4.3 ly7wf1+o;+ rpv lavtjx6 ?

  The apparent brightness of jkyy,rj 3 /k)j1xultre5y4iq vza.prb225a . a star 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 agzxjb lrf0 n 3(:6u3vdsaq60 mte of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in yearszmrju:3 ltbd0q (xf36 sv6 an0.

  If a galaxy is moving away from us at 1.0%dvvb8t+jcp*l ju+0h4s *j*o i of the speed of light, how far away is it from8 + l** ub+sjh40oi vjcjptdv* us?

  Estimate the speed of a galaxy that is ck1.7 cle*c q/kstix310 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star (ec7r4 j:0i ecwmwj2iwhich is 100 million light-years from usemew 0i:ijc7r4 cj2w(.

  About 1 ms after the Big Bang, the temperature of the universe was0,cf:b2izpflt. q v4t*l5kshfz0,,i r h9 k ai about 1013 K. What energy (in eV) does thiqp:slk9tf4r5,z iabcz20 *0i., f flth, hv iks correspond to?