The appearance of the great range of brightness among starkic6p)ho o4g .s is due to

  The absolute luminosity for most stars depeb2o:xs:hx+/vwt on8bam - 9 asnds on the

  Four different main-sequence stars are c4 n9;lamhotw b3.0laqolored blue, orange, red, and yellow. What is thelaw aq;h 9t4onml.0b3ir rank from coolest to hottest?

  A Hertzsprung-Russellw6 i 0tnnbu saqt1a;7: diagram shows stars on a plot of

  A white dwarf star witheyglu2dt3 7bbj,7j7 v a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a srbfnm (+ol7-w7zcsug:jvir99 * 8. i 3qlmtnhtar will collapse into a white dwarf) is, if the mass of our . +ri mhm9jor n(gwfuitq7 c9b8znl3vls-7:* Sun is M, about

  Supernovas are thought to always result .gi cqzv)r+hn,;7febin

  Black holes

  Pulsars are rapidly s73d h+s-gg9b b 9m:crhi// 7gplbesyupinning

State Einstein's principle of equivalencei;yny5e vx / pab ye/.bbs8,p+.

  The Schwarzschild radius of a black hole is that radialc8kku:5vikmx-v, s)*n bg *bz dji aox7):t)j 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 relativity theory. Itjc tx k:m ),bxszbj kai)u)vg: d5-8o7ivk*n* 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 emip, jq 8skt,1ztts light of a particular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to t,1qp 8zjst ,kbe shifted toward the

  The cosmic background radiation correspondvur oxsikyk*, s0s).+s to a temperature of about

  The Sun has apparent brightness 1o,erq;62; qutr-4km7f vd altau8 cbat 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 lumb-8wtrzd,+ 3( drocyl ,q ,iyiinosity 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 /ik(0 *n7hlg :mx mtthjbed24 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 km?

  The Earth's orbit has a tw0 6:; tzd p-g qyxq+k ,e92klltk:cemean 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 Cen*p/ .-r( lgn ocdz*ut1 k6xt-kq(ujfbtauri, which is Earth's nearest star at 4.3 lo g6f pk(n brk/u-t-tdl.*z cj qx*1u(y?

  The apparent brightness of /w 9f-zx rvv 3/rg6xela 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 age of the universe is 1/H, wherxh9 2fr;zoa( evligek. (0:fne H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in yearev2gnf :efa lhzo r (k;ix0(9.s.

  If a galaxy is moving away from u )bx3k z6gt)bls at 1.0% of the speed of light, how far away is it fr)l6btzgkbx 3) om us?

  Estimate the speed of a galaxy th6u/fetn-l0q vw w85c jat is 10 billion light-years away.

  Estimate the observed wavelength i tdedftv:r) 66oow1+for the 656 nm line in the spectrum of a star which is 100 million light-years from e1dotif:6+d wvt6 )rous.

  About 1 ms after the Bfg7 . m8uq. vw34siwn4whs *soig Bang, the temperature of the universe was about 1013 K. What.3swf*m4n8q7gwv s .4 h isuwo energy (in eV) does this correspond to?