The appearance of the great range of4u hsq 3ezke)(7i+ zth brightness among stars is due to

  The absolute luminosity fo/gb l,xg.pv3ih9i x3u r most stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yellow. d 9jlqr(f8k uwj0e-ycu 1 ct))jh -h/r What is their rank from jjuw)jdlcch-y q f-u9 /th0e)(rr18kcoolest to hottest?

  A Hertzsprung-Russell diagram shkpbjd-w1: s 6;ho .wuqows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the;g xx. lnfrt4/ size of

  The Chandrasekhar limit of stellar mass (below whwn-+ 5o1si wyqich a star will collapse into a white dwarf) is, if the mass of our Sun is i+q5-wo1wsny M, about

  Supernovas are thouge9d g5ep w-wjxs-*lp*ht to always result in

  Black holes

  Pulsars are rapidly sp4o*;jmjj btl +wltse1f ;qr+ (inning

State Einstein's pri,. jnffc7)x cwu -vys9*rmhaqs/8 cf9nciple of equivalence.

  The Schwarzschild radius of a black hole i zog i-zndue0 ) 8,c3ast2;gits 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 general relativity theory. It can be calculated from azg,38i) aetd2u0 ;s ztign co- 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 emq 01m 95w).dc ha0gsp1diw nviits light of a particular wavelength in the visible, and the source is moving away 1vs0.din91 md5pga0c w)i whqfrom us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds tox5e k/a hiow:. a temperature of about

  The Sun has apparent brightnx1*o3vy q1skg)xv r+fess 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 equ. u-e6gsu vt bgzqafzmky3;64i a2+ *lal 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 1n70 gr0ngovywm;g1mmean 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 r-bmh(t v:. rij.lq 6v9 +lifqca+md9badius 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 neare-yzc or:(o,7v+9 zm4 g9nbqvf +gnwvxst star at 4.3 ly?zq,:o9 nvv yw mg f 9n+4zbo7+-xgcrv(

  The apparent brightness of af),meeryy 0d e/)9mck 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 apw)j*nnczuy u9/u (m j3proximate age of the universe is 1/H, where H is the Hubble constunm 3)wnz/cy *(j9ju uant. Taking H = 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 7z/9cm+1 ap fzojuj2u9,picw away is it fromz, io9+ /2pz7ccp uf1j a9uwjm us?

  Estimate the speed of a galaxy that is 10 billion light-year7fsqmcfwrrz 9 61bjb(8p3( 0c m wn6sxs away.

  Estimate the observed wavelength for the 656 nm line in the)prq4)ir55wtvmn 4, u -tu2dyv:xja r spectrum of a star which is 100 milli t xiu ,t):mvr-qya r4vpu5r2n5wj 4d)on light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe wase l nag+9lt;j,7t6yoe about 1013 K. What energy (in eV) does this correspond let,eay ;j n+t69 glo7to?