The appearance of the great range of brightness at rrbo 6 yzf3j8uc.3j9g:(pn wmong stars is due to

  The absolute luminosity for most stars meq 8g9z l l,kesa7p(4depends on the

  Four different main-sequence stars are colored blue, orange, rp:wq25 re; ixzqj(+rled, and yellow. Whatrqi52xw;e j : r+plz(q is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on 1wxokibc b5,79v cji4a plot of

  A white dwarf star with f y8r:v/xzrv9*4 )9oflsxqpa a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will h,:u,86h eel ujv;f76v muvfe collapse into a white dwarf) is, if the mass of ouruf :ulhvfve h7; ,u jve,6m8e6 Sun is M, about

  Supernovas are thought to alw nh5m0 hzm3xs4ays result in

  Black holes

  Pulsars are rapidly spinn/dq)0 r9txjuzing

State Einstein's princip /ndsj:0df/3) gtzpyr e21.bz 8tbec dle of equivalence.

  The Schwarzschild radius of a blacjce+c0vit )1mk hole is that radial distance from the center of a sphere within which not even light can escape. It was first discoj ci )vm+0tce1vered 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 ppdw0ghlkx :arqs;w8a o ir6 )4 k-5il8articular wavelength in the visible, and the source is moving away from us, the color of klrlqirai0-8g 5):p kh;x6ws dw48o athe light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a n1)g) bk .ql4ctpm;k ztemperature of about

  The Sun has apparent brightness at r3yul98 88;w2 s jn0fakgod ihEarth ($1.5 \times 10^{8} \; km$ 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 Scrw3)4 r ;j+wxa .djvblbm3p.un ($1.5 \times 10^{8} \; km$ 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 manqj0s eao. vxx2:-00+a g rnzean 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 rad9d) ;1 8yi,.c:lnh df4xg5itdpaf95skviwe lius 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 fof:xshthy z;hazc *3 +3+r;wsu r Proxima Centauri, which is Earth's nearest star at 43h zt +*+shs 3:rzuyfca;w;x h.3 ly?

  The apparent brightnegzedc9n*apid73 jzlh/7 19 ,.cq ih yyss of 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 is 1/H, where6 ayusx,4( ta./sele l3u9l csp;wuw1 H is the 4/x;a9s.ewu,pt1a(l6ls cs 3euylu wHubble constant. 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, 3itasr,c 4 6nihow far away is rits6n,4 ica3it from us?

  Estimate the speed of a galaxy that is 10 billion lightm d5hce4qn2u*-years away.

  Estimate the observed wavelength for the 656 nm li76l6 ku,qlpz+w9 npfo ne in the spectrum of a star which ,oplz pwn kl69q 6u+f7is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universtw9+ ru qhk i6m*v)fa5e was about 1013 K. What ene w*)+ti5h6kq9mv fura rgy (in eV) does this correspond to?