The appearance of the great range of brigh9davd zo.l(y;0lj 0vpd4. foftness among stars is due to

  The absolute luminosity for most sta/h5pq g o(r.kkrs depends on the

  Four different main-se68w l5 p4d8q;byqtcbd quence stars are colored blue, orange, red, and yellow. What is their rand w5y pb88lqb6t;d4cqk from coolest to hottest?

  A Hertzsprung-Russellbdayvlk35-mx w7;v w; diagram shows stars on a plot of

  A white dwarf star with a mass equalz8rvgs 3hx)qjf ()t i; to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass lsn9i1t40pe0x /o kac(below which a star will collapse into a wlce0k / psoni401 9taxhite dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always resuyz1qgyki s wdzc:7 q4ffl851) lt in

  Black holes

  Pulsars are rapidly j5 3oh.+qaq tpspinning

State Einstein's principle ,p 03u3-;pll lko2 goiiw ru(yof equivalence.

  The Schwarzschild radius of a fnx;qwe 0n/*o sx;0qg black hole 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 published his genexn qx;g; 0*e of/snqw0ral 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 part 6b9w kh)mhr lnu;z*o0icular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shifth ;w)* obnkmurh0 96lzed toward the

  The cosmic background radiation corresponds to a temperature of abdjr :lm -:hn9cpb6 0tjout

  The Sun has apparent brightne e k.:o1ip(;kpti0xkq*k (git ss 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 (:ew0gu6y7 gh g$1.5 \times 10^{8} \; km$ 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 nq2aw u )enj/xep 1h 4d0s5ah6a mean 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 radius of w6u2abe y. cn tkdmdm g;u2/82$1.5 \times 10^{8} \; km$. 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, wh sil4.;tv kc-hich is Earth's nearest star at 4.3 ly?slv kic- ;h.4t

  The apparent brightness of a sbi o grjz48t: js:j*)ttar 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 universht1x)c8 w2ujjc ;.o; skq(cwae is 1/H, where H is the Hubble constant. Taking Hoahwqtwks (c ;x; 2u j8jc1.c) = 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 b zk96-mgv,tfis it from - z9m 6tb,vgkfus?

  Estimate the speed of a galaxy that is 10 bill jy 19hl))hjbj, wd1ition light-years away.

  Estimate the observed wavelength for tip u/n/ra+aow wl00 94u bjy*the 656 nm line in the spectrum of a star whic n0a uwau0/*t/+4jo b9w ipyrlh is 100 million light-years from us.

  About 1 ms after the Big Bang, the.bji9 y4s/t h3a8 ntbg temperature of the universe was about 1013 K. What energy (in .b4t93/i8snh y gtajbeV) does this correspond to?