The appearance of thzc;h/ bh /3a.fz(zx m fjg:4nje great range of brightness among stars is due to

  The absolute luminosity for most stars w czus f)2ye*8lw1d 0u eo1 rejx2+4sldepends on the

  Four different main-sequenc q)o93)2cx2n;oj - kft zrkps-m9 vwzae stars are colored blue, orange, red, and yellow. What is their rank from co-nkmj)co w fq2 3tpx;ak)9-vz2 srzo 9olest to hottest?

  A Hertzsprung-Russell diagram shows;* .vh yr;of9f kc9jwv,-fump stars on a plot of

  A white dwarf star with a mass8fh ) mzhp:s2tp+v7ka,nc4f6v)m bs j equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will * hn,+gio2y tucollapse into a white dwarf) is, i2n*u g,oh+ytif the mass of our Sun is M, about

  Supernovas are thought to always resd bv:q:zzqoll(0us6 (q*w yh5q g6 b*sult in

  Black holes

  Pulsars are rapidly spinni 8lxk w.w-rnsjcb o71(ng

State Einstein's principle o8 te/zi4ycpfq;jqb6 ,(p -qb4,pgwg if equivalence.

  The Schwarzschild radius dk.skxs wk+d3u0i .*;. beax iof a black hole 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 gen d a s;..xbxk. i+dkwu*keis30eral 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)6vxov9tjm 7 ecw 4,tx visible, and the source is moving away from us, the color of the lig tx7ev 6)co,x jwv49mtht appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temu+-tc4( zhgspperature of about

  The Sun has apparent brightness d22wo 2ccpxwd18a)asqrw; b*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 thqkw4l8 znxk (:at 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 me t/*,kb3o5uw-d/kmg pnh f; v*3cjmgjan 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 usun7q b.mr880.cown 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 Proxima Centauri, which is Emjrq)bh/d0 u*)xwrz b/l 3o a)arth's nearest star at 4.3 o)b ml3*d ra)xrbjzw0) //hqu ly?

  The apparent brightness of a star ivi.h:9eh* u dcs $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the uns cy wzk,pf3yyk.ddg*)y: g7,9hmqr 0iverse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in k k3s*pygmg dz0qy79yhf ry : cd.,w,)years.

  If a galaxy is moving away from us at 1.0% ;nr(* ik76qoja;pp ya of the speed of light, how far away is it fr;joq6 r7k a p(yna;*piom us?

  Estimate the speed of a galaxy that is 10kqjc.m/z 8i4 a billion light-years away.

  Estimate the observed waveleti 8f40kco8x angth for the 656 nm line in the spectrum of a star which is 100 millock08 a8f4tix ion light-years from us.

  About 1 ms after the Bis0ctq9yczow9 )cvio a. 8z. l,g Bang, the temperature of the universe was about 1013 K. What energy (i,o lzc98wios tv)z c.c9q. ya0n eV) does this correspond to?