The appearance of the great range of brigjia zbsj*j0x+2i;a 8afg7d g; htness among stars is due to

  The absolute luminosity for most stars depe.m67x/cw n-0-/mmrma ud4: kwcbzw vjnds on the

  Four different main-sea i (kv0a 1;xsxly/e/gquence stars are colored blue, orange, red, and yellow. What is their rank from coolestx gai l(v/ yxe1sk;a/0 to hottest?

  A Hertzsprung-Russell diagram sh)xq:s ej)h82g2f gexmows stars on a plot of

  A white dwarf star wigbzy fbum4b/h 3 3*+w;aeq4yzth a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a stao c*mmku *2j4tr will collapse into a white dwarf) is, if the mass of our Sun is M, abouto m*tjum*ck24

  Supernovas are thought to alwaxc-5rg)vd s4 u j4u4muys result in

  Black holes

  Pulsars are rapidly spinninkh0 1dji u jioz.j3/3wg

State Einstein's principle of eyy v ax,gs,l))quivalence.

  The Schwarzschild radius of a black hu0kf:lh4ncy3t -ju: m3 4bpovole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwkbl03uu:m 443fjy- :ohcpnvt arzschild 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 particulavs(j(h32i cyt5 dzyx+ r wavelength in the visible, and the source is moving away from us, the color of the light appears to us to b s(yvx2d3(zht+5 ij cye shifted toward the

  The cosmic background radiation qg ,yn *zl04)p sip0edkp05pe: zats8l +*pjqcorresponds to a temperature of about

  The Sun has apparent brig- bre. d:e.foxhtness 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 luminosin(hvvs7ij-k/g 6r9pu ty 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 q )tf- e:mmv3va 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 mean ru+ fvnn(1oms :adius 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 Earth's nearest s.7q2( hhacn.wlvjr2l nz,s mz0v t6 ,star at 4.3 l.hl.2rmw,nz vcn(2tq j,s6vs haz 0 7ly?

  The apparent brightness of a star z(2 z1wmac,fj 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 apprs)u eo6s0 vzv5oximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate thev6esz0vus)5o age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of lh s,,f1 6/3fkueue irqight, how far away is ite1kuu,3e sfi r6fq,h/ from us?

  Estimate the speed of (+ssjofm4 o 8)eq0s7pcxf pj5 a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spee szbud tb4( zy8763hqrunk. *ctrum of a star which i.73hu86 bdyrbstkuz(e z* 4qns 100 million light-years from us.

  About 1 ms after the Big Bang, the t(0;qiugq xg( 6-uvzecx / uf-jp2db7x emperature of the universe was about 1013 K. What energy (in eV) does thii ef-x/;-b g(u6 (qqzxu2gvd7uj0 px cs correspond to?