The appearance of the great range of brightness among stvt*p*miym4 fg.qci aq;*9 d)oars is due to

  The absolute luminosity for most stars depends on the j iz:l,g3igh.f9)dkg // qq5irc3wd o

  Four different main-sequence stars are colored y2m2nnj8) gqzblue, orange, red, and yellow. What is theirnnm) jg82zyq2 rank from coolest to hottest?

  A Hertzsprung-Russell d5*qyci,9m7gh h1k jte. tzco- iagram shows stars on a plot of

  A white dwarf star with a mass edfy 9gh27fgh5qual to that of the Sun is about the size of

  The Chandrasekhar limitt10x-hgr 0ts pidtq +4 of stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M,+q 4t di1- htxgr00tps about

  Supernovas are thought t-)-ms/ ak;xt0b ctu+wv w*u z:u9maveo always result in

  Black holes

  Pulsars are rapidly spinnik fx4r 0o mm+au*k9h. 6blhbb6ng

State Einstein's principle of equfojxo gv:anl-t( rz8d 91t)c(ivalence.

  The Schwarzschild radius of a black hol9r78m35le/ nf6ft bxyej-ieee 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 publisheffljn9 -bei58e 36etxm/r e7 yd 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 tvgzlf 1)+eepgseh 5e8(od3-j he visible, and the source is moving away from us, the color of the light appears to us to be shifted towaro fej+g(1 z)eh35epgdv-e8sl d the

  The cosmic background radiationwekw0 od3i+riox23 4h corresponds to a temperature of about

  The Sun has apparent brightbh jo; :9svof.ness 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 that of the Sun (5cm41 ho;m .ovi t3nvt$1.5 \times 10^{8} \; km$ 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 r u9.s8ci.u d4qb pygd,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 km?

  The Earth's orbit has a mean radic zf2 w+.9r+s3 gzyv,kkribe- us 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 neare7c33 /3i fwc:cp vznexst star at 4.3 73cn/fpe:cc zwiv33xly?

  The apparent brightness of a xqnoeyuu */,v6bj3dxzer2.7star 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 approximate2r;qbkdj3c9kdstk(+ lo:*9gwkl (x b age of the universe is 1/H, where H is the Hubble constantkkrd9d :;2+b owq*9lc(st 3kjxlkg (b. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us a o4c7c:cilp m6t 1.0% of the speed of light, how far away is 6ocm: lcip 47cit from us?

  Estimate the speed of a galaxy that is 10 billit0 q8l-ppgmc0 on light-years away.

  Estimate the observed wavelength fh)jn 5tx)n qn gg-g1tprds58 3or the 656 nm line in the spectrum of a star which is 100 miggjps5 ) 3qh-tnrdn)gn8xt51llion light-years from us.

  About 1 ms after the Big Bang, the temperature of tk: )pmou,wd0i he universe was about 1013 K. What en)o im:,uw0d pkergy (in eV) does this correspond to?