The appearance of the great range of br .byj3k o*o raj39+: 7ewuulioightness among stars is due to

  The absolute luminosity for most saf:o)m 1bjatm+- qvi wbl3o6*tars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yell*l u: p8z,iupjow. Wh*,pj piu u8l:zat is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a3ggifk v +ri-.q -iwa6 plot of

  A white dwarf star withvt, jqoa7mdp:q + zh29 a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below whe*y7 vghxch8jgcoxb; dgrs; ds/ 8(3-ich a star will collapse into a whievjhco;/x-g dbh 8xdr3c8y g sg7*(;s te dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always result inuwjox.ly5: pc :;; p.h6sv)dle ) k6sfbs;cin

  Black holes

  Pulsars are rapidly s9t 6+f7kmg;n cfbr l1upinning

State Einstein's principntfn(oe k4e, 1le of equivalence.

  The Schwarzschild radius of a black hole is that ra 3j lddsrh jrlww3)7)/6*rv slu25xz hdial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 alv) dlxh6h*s l3j 27drwszru/5wjr)3fter 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 opq+t .d0t 3embf a particular wavelength in the visible, and the source is moving away from us, th3. b tmetd+p0qe color of the light appears to us to be shifted toward the

  The cosmic background radiationn.5 sk8)n(q9dwys khs3c;i jr 3u0iue corresponds to a temperature of about

  The Sun has apparent brightness at Ed94oe+4 xik -*/tx8koy 4w led wfdog:arth ($1.5 \times 10^{8} \; km$ 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 thqbc7x4 8ei w6ly. 7fjsat 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 oi t khd:93ohusm:)5ugf $1.5 \times 10^{8} \; km$. 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 ayu epkrirk8vph xxnz5 244ky,:331wj 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 Ear hw;dv/ npu22e1ff i((tx6xeeth's nearest star at 4.3 wfh exit/pd;( (n21f26xvee uly?

  The apparent brightness of a star qc9 w2lq2l3bjpz8 nkp,b guz5d1ap89is $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of thkx ia 7w+*5dgre universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in y 7grdw +k5xai*ears.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far away iort3c-b0 5f-v uwx 7ducd) n0grez,r: s it fro b)dc-r:0w r dn7vg3t fec,-0x5uuzorm us?

  Estimate the speed of a galaxy that 3uww5t+ qc5dg is 10 billion light-years away.

  Estimate the observed wavelength forxjni gh71cr;+ the 656 nm line in the spectrum of a star whgcjxirn 7+h; 1ich is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was ab 7 1ec//j8ybqnrl,j fwout 1013 K. Wha/lj/ eb8jc7w1q fny r,t energy (in eV) does this correspond to?