The appearance of the great range of brightmzkq 0skt n2cr;8sr,e b4teg bj(2w1(ness among stars is due to

  The absolute luminosity for most stars depends on thaw4l;k,7d db ie

  Four different main-sequence s6m q1tubx.bdz1 pd*q mg(sd,/tars are colored blue, orange, red, and yellow. Wbd/q s,6x m 1p.qgudt1bd(mz *hat is their rank from coolest to hottest?

  A Hertzsprung-Russellx:qd:)at- cvrq:o ,b+j bmo ;wyv3v 5z diagram shows stars on a plot of

  A white dwarf star with a mass equal to that k/sx z(qksbntzmx59i0wo18-8ws zc6 of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below wip- ;ieod 5op9 am+s,jhich a star will collapse into a white dwarf) is, if the mass p-;pdmi+5 eja9,o osiof our Sun is M, about

  Supernovas are thought to alwasv - poaxw9fl yrxlu.iz;ze up37(3mu 27/ g.gys result in

  Black holes

  Pulsars are rapidly spinninko t jfc-q+0a5rn7mk- g

State Einstein's principle of eq2g-1.6zka m ia,ogkquq:a7 oquivalence.

  The Schwarzschild radius of a black hp 8x4 3/7 haisnxa9ogcole is that radial distance from the center of a sphere within which not even light can escape. It 3s gnoix 8p9a/ah7cx 4was first discovered mathematically by Schwarzschild 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 particular wavele+bbt(cwaj23 s ngth in the visible, and the source is moving away from us, the color of the light appet bs+23(jwbcaars to us to be shifted toward the

  The cosmic background radiation corresponds/fbzb14eg pu3 to a temperature of about

  The Sun has apparent brightness at -.(lvpvb -pdq;o q9b- o(b4c ijsk*qdEarth ($1.5 \times 10^{8} \; km$ 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 tha1-lm)j1cp cfg t 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 m+q lb )qiim8sw6y2w.eean 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 mem+ 7qzjk3x:v 0 hbpgp5an 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 Earth's nearest star a-phm d.q*df 2g6grk3l6p mg23q*drg ldh-kf.t 4.3 ly?

  The apparent brightness of a starzfw x7u ,mw8v/)z o)jx1vxug( 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 ish)+/n m zjh1sv 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of )mj +zhsh1nv /the universe, in years.

  If a galaxy is moving away from us at ygou8w v;+/n ;/igp oj1.0% of the speed of light, how far away is it from i u+yg; oj;/g owpv8n/us?

  Estimate the speed of a galaxy that is 10 billiov n7s jr 0 r4q4egpl:9isn/1ysn light-years away.

  Estimate the observed wavelength for thehin.i7hj0q z/j:6k w w 8akfw* 656 nm line in the spectrum of a star which is 10:jkwi0ja /kwh hq*zi .6w8f n70 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 pj,b 6foh st)2 og4k*aK. What energy (in eV) does this c*f 4tbj62k , aoos)phgorrespond to?