The appearance of the great range of a.:lj/*oam;0b ia pesbrightness among stars is due to

  The absolute luminosity for most stars depends on then )d5,.uhak h1nt4jc e

  Four different main-sequence stars are colored blue, orange, red, and yellow;lseo/6 wh *br. What is their rank from coolesthl/ roew*bs 6; to hottest?

  A Hertzsprung-Russell diagram shows stars on;xo /)t qr,b*7lhwbr e a plot of

  A white dwarf star with a mass equal gk-1y,bct(7wm:5 gpwg(c i klto that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse ki30aa2zd6rc into a white dwa2da6 0z c3airkrf) is, if the mass of our Sun is M, about

  Supernovas are thought to9p cy;wlxw-x.:hy-: vb ,uswq p+dw5o always result in

  Black holes

  Pulsars are rapidly s 1gy; gfam)hw/ 1cl jcqir6 603yfb4unpinning

State Einstein's principle3 k,-o kl6dovbckw (fz8(vas) of equivalence.

  The Schwarzschild radius of a black hole is that radsglcju ,xw 99z)f wtz5(;kr5yial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Eins5uf wly(x,w5; k9 tcjgz9 r)sztein 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 rgn8fmz2+g k kli8)y3 light of a particular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shifted toward tkr8i)+ y32nm8 gf gzlkhe

  The cosmic background radiatio18wu s;:wfk oun corresponds to a temperature of about

  The Sun has apparent bright8g6e4nqk wl*5 jbvh8eness 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 Su(s lpitkb qac h.43.5en ($1.5 \times 10^{8} \; km$ 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 rayfjrn6yor1i/p;g 30mdius 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 u+:3ekengq2soiw .,i 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 Ce 7 b;c-qgeynw)ntauri, which is Earth's nearest star at 4.3 l;wg -e by7cq)ny?

  The apparent brightnesu7c*hv .js h)cs 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/q3bu, x c-thq.vlkmp0b8 d jhmkw:/z350b y- fH, where H is the Hubble constant. Taking bvktm j83.b3/0hh:0 ucy kw -zbp-d5fmlxq,qH = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of b b+(e5b fc9xqthe speed of light, how far away is it from us?bbf+5 q9cxeb(

  Estimate the speed of a 9epkhpk 3/v6fgalaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star ws1 o8qqvw6snevb a4v6c) 1s ax j)la49hich is 100 million light-years fr11sja 6vqvl) sx a) 48n6weavocq4s9bom us.

  About 1 ms after the Big Bang, 2yvat0lg tcti04 7ih: the temperature of the universe was about 1013 K. at :hii gcl7v2tt0y 40What energy (in eV) does this correspond to?