The appearance of the great range of brightm+q vwe -9a-p-bbg)f tness among stars is due to

  The absolute luminosity for most stars depends on owe.3ogl /6ehthe

  Four different main-sequence stars are colored blue, orange, red, alo.utgjn6ea+o 474 wj nd yellow. What is their rank from coolew.4ou 4eaong 6ltj j+7st to hottest?

  A Hertzsprung-Russell di t4ye b6)gyhoo53kaqy97 osy9 agram shows stars on a plot of

  A white dwarf star with 4rae4 a5;xdpayrc4 u. a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collaue-6dbyww s5 2pse into a white dwarf) is, if theuwey-6d b5s2w mass of our Sun is M, about

  Supernovas are thoughtwcn1)7uue )flv+o yvmyfj(h. o 7*w u1 to always result in

  Black holes

  Pulsars are rapidly spinningada df3v*. td isln/+b5fx+i2

State Einstein's principle of equivalencebnqg)zu6r h21.

  The Schwarzschild radius of a black hole is tha1 a6)n fdn.owyr7xi v-t radial distance from the center of a sphere within which not even light can escape. Itv wo)n76ra1d.n fy-xi was 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 particr 545xtmxzyw ,51ibbaular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to,b5b y5xwt1xzira5m4 be shifted toward the

  The cosmic background radiation corrjb37 qend622zbg zl:dy mk70g esponds to a temperature of about

  The Sun has apparent bright: o w7 q(a8.:satqsdsrness 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 lumj3h9h3je8jw0ys x5 jgw /d y,sinosity equal 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 mean radius omtn pl-8 6a(tfq-exf-yq 4j/ pf $1.5 \times 10^{8} \; km$. 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 hasck6sz7y 5qswr 76qej(lzh,akc;33w k a 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which is Eam + mrjsa 0l)un8m*wy6rth's nearest star ama+) rymnlmu*j 68sw 0t 4.3 ly?

  The apparent brightness nb2tjp 0i66rgn wm23rof 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 ts 9ox y,.i)iqjhe approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universeq9i oxjs)y.i,, in years.

  If a galaxy is moving away from us at 1.0% of the speed of lcw4hy0:kfu )jhyoi )e1rnt)7 ight, how far away is it f0wye)o 7ic )ujt1yh r):nh kf4rom us?

  Estimate the speed of a galaxy thatn qm) wl+hr1b. is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a 8xduygps zn k q95x6pnj( m 2ivf/ n:(p7x9gg8star which is 100 ms fndu5jpgnk/z8xx(9nq8p7i9: g 2 ( xgpyv6million light-years from us.

  About 1 ms after the Big Ba3e/u,gxafv9b m*9z78t oohuk4xj 5xctx1y 2 wng, the temperature of the universe was about 1013 K. What energy (in eV) doesex bkxa2xh fw9o1yg4c3tv uxt79*o ,/ j8mu z5 this correspond to?