The appearance of the great range,6 g9sv u..t.xtf6 q zcqhidq,v eo47l of brightness among stars is due to

  The absolute luminosity for most stars depends opq)b a2rhkmoe *,/1fzg owb99n the

  Four different main-sequence stars are coloz0 1ab4k 4jropred blue, orange, red, and yellow. What i jpa0obk414r zs their rank from coolest to hottest?

  A Hertzsprung-Russell dwyra1i4p 6( faiagram shows stars on a plot of

  A white dwarf star with a mass equal t ftui c/x;0k8yb urt;4ch 5.qxo that of the Sun is about the size of

  The Chandrasekhar limit of stellardp evjd6nsf30t- t)jnw30g7v mass (below which a star will collapse into a whitevg3v 7wn0e)jtdt 0pfjd3s n6- dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to alrr95x o7e s6zjph r5z;ways result in

  Black holes

  Pulsars are rapidly spnkil()(kzq74i s 0lzu inning

State Einstein's princi)8e 3sk jpez3nzwb6,h ple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cenf 8yw0l0km dv/ter of a sphere within which not even0ldw0f kmy 8/v light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general 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 particular wavelength in the visible, .be dq-*zn0lyf y-sdn3a r+vyu:aeg mb88s+ 9 and the source is moving away from us, the color of the light ap.s9- n+a*q8bfe8zem+ sn gr0-v 3udya:dy byl pears to us to be shifted toward the

  The cosmic background 2t qb +i +(,vrvvpiwi)radiation corresponds to a temperature of about

  The Sun has apparent brightness at Earthyza9,1qz+c ug7m- tnt ($1.5 \times 10^{8} \; km$ 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 luminositwwb7k* . 8kwk 02y*0fm,7 ya fdkzonizy 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 me3j))bm okd)01xw mhoman 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 mean5av)0- smd; (foegofn 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 angrao/w at+*m6 c)5akbxb 9;dv sle for Proxima Centauri, which is Earth's nearest star at 49bs/t5 +a* xca k;mar)vb6wod .3 ly?

  The apparent brightne -7 o7bln1uzj.pesi,gss of 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 age of t+i kl. xul oj/mfc;fy- 7u)uj.he universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate tliuux )f/mkyljo ;u7jc-.+. fhe age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light4a ougrfuo+;* , how far away is it +a;*uou4g roffrom us?

  Estimate the speed of a galaxy that is 10 bu-2 aj7 dz y.6l5z3d)mkzpf buoq:ai-illion light-years away.

  Estimate the observed wavelength for thejsq0 h36jb1jz+th 94xxokzny/r33;gd-i btz 656 nm line in the spectrum of a star which is 100 m;jx hrj+qkzx i/y33bsnjzzh 3t96o4g 0-t1d b illion light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about hax;j(zjb ;cn1+4- g qkw,hng 1013 K. What e c4j1jgg(nzb; -+nw;xa,hk hqnergy (in eV) does this correspond to?