The appearance of the great range of brightness among st iwe;dp5:xcz1ars is due to

  The absolute luminosity for most stars depends :ql l.r1xhm g)+0tf+i zg7s jxon the

  Four different main-sequence ;pbxv 7rm/a nmf 99ec*stars are colored blue, orange, red, and yellow. What is their rank from coolest to hott9 ;c/nrmfba 7px* 9mveest?

  A Hertzsprung-Russell diagram shows stars on a plo q :qngi v;o0e+(;pyaat of

  A white dwarf star wi w80ylpwi. ncwz8 g1wk( .+biath a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse in 5o*n wtjcb: 9oz26klgto a white dwarf) is, if then5bzktlj9c6w o:g2 * o mass of our Sun is M, about

  Supernovas are thought to always result ij2v.z5anbi s 5n

  Black holes

  Pulsars are rapidly r7i2pvkmcdw6 zw j0 (:ff3;uzspinning

State Einstein's principle of equivalengu 4gnfih y,09q8;ms6;su jeh ce.

  The Schwarzschild radius of a black hole is that radial distance from thn66knmkoh:*ipt3z )cpsn ,wl d -psq/5v(s;o e center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 191pvcnqp);pdm*n( 6s /sk,ioz3 -hls: twnk56 o6 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 visibvw; k ,5bygh; dknurelb 7(5*b+tqdu+le, and the source is moving away from us, the color+d,5 gdhb wtkq* ubrulkb;(e7vy5+n; of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds t;dp)yru;y +y to a temperature of about

  The Sun has apparent brightnessvg vswjz 6o(:yfqr -uklk.2.0 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 lus/a2 j4q4o n*;kv-0v lkida idminosity 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 mean r0s zqq- var2+gadius 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 me l3 :vai hm26k-e xa-4ry*pgxban 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 Proxiz2u ;3t/ukgb(nit kiu )x4 k2qma Centauri, which is Earth's nearest star at3ib2u; /t ngkqi2 )t4ukx zu(k 4.3 ly?

  The apparent brightness ofy3rcwb1q7dm jc rt2t-r(8 z d2 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 the universe i7e90,sqf:;en f lquvbx1, vq3i js1jes 1/H, where H is the Hubble constant. Taking H = , ej1;iq9f s,e0nqjveb:x73q lfusv 1 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far away i o5 8x4t)wss3 :ux:ylpvdwk ueff7-5ts it from us?p4d8s ett:xf:w wos7-xf5 k)3yv 5luu

  Estimate the speed of a galaxy that b,md fb hn. ladr+)a* u7ta82gis 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line izmkmy+ +)y4lo(s+hfz n the spectrum of a star whiy +4l+(msf)zhoz mk+ych is 100 million light-years from us.

  About 1 ms after the Big Ban u5a: v*vv xa vn79y6kifb7ox.g, the temperature of the universe was about 1013 K. What energy (in eV) does this correab9a .vxf7kv6 inov u :7xy*v5spond to?