The appearance of tha x.;aex 7)nare great range of brightness among stars is due to

  The absolute luminosity for most stars depends on thzt:c-glee;tp9id *nz- eh g:4 e

  Four different main-sequence stars are colored blue, orange, red, anp .ikg jzw ,/froi5i/vn9-*d kd yellow. What is tr ,*g/d-95kfk wzi.jip n /ivoheir rank from coolest to hottest?

  A Hertzsprung-Russell diagram sh uck7ci zl /*;+u byqk;q)cjw+ows stars on a plot of

  A white dwarf star wita 7ex6.d3k0sum )wpb9jr3k reh a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star witxtl55w w:1a 0+wjp 4trmttn- ll collapse into a white dwarf) is, if the mass of our Sun is5tjwrt0w a5+t1npwm:xl4 -tt M, about

  Supernovas are thought to alwa.yx 2dptrw7 a-we60s pys result in

  Black holes

  Pulsars are rapidly spinnier4 cgk/u*s (cng

State Einstein's principle of ej93xickk z4vfi wc. 4mq z;,8lquivalence.

  The Schwarzschild radius of a black hole is that radial distancei:i,)dp2,6cdb.( oyq la)gxle vz v8 k 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 hiidlvb, pck: . g ql62x8o)id)yv(z, eas 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 particular waxnfqpyf*;yy(py v (51velength in the visible, and the source is moving away from us, the color of the light appears to us to be shp ;*5yyx(nfpqy1v (yfifted toward the

  The cosmic background radiatidmi7jfx s7 ,;aeml.+vnvj 8 2/mkn)fnon corresponds to a temperature of about

  The Sun has apparent brightnew v jpha qa5r(r6praf0k43 (f8ss 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 equcce))xz 0;lxsn6,vbeal 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 z c +pdydim+8c7 :uig32zle h-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 radit(d)qnu .qw9uko1ge u,,tq9c us 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 67nab x5hockdx,v o.zk *h u+2Centauri, which is Earth's nearest star at 4.3 lx+vc7h. on,d6 zu xh*k ko25bay?

  The apparent brightness of a st li*l i.r-p3qoar 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 app 5 e d6qmiq)pbe7udv6a4 hk2d.roximate age of the universe is 1/H, where H is the Hubble constabp4e2um6edhi. 56 )qvdkaq7d nt. 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, how fa6*8wj yx *9gk9+(xixpsxoob,z9gnnfj.v * lv r away is it6*g jiyvw.8olx nn gj bz,ox9+*xs (pkx9f *9v from us?

  Estimate the speed of a galaxy that it irdwp6e (n:vcc47b-s 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a mn *q1x1ny:ahy*m1z dvzg v1g+o8p6t star which is 100 miln8y *1y:m vgo x6znq*1ghtvm1+d a1p zlion light-years from us.

  About 1 ms after the Big Bang, the temperature oo7ekt a. s3 6w4viynt8f the universe was about 1013 K. What energy (in eV) does this correspo wv7tyei68 t.asonk43 nd to?