The appearance of the great range of brightness among stars is vox1 e5mnky m-2s-7 9.nhvjl+ edwrp(due to

  The absolute luminosity for a lo zze0h)j;5most stars depends on the

  Four different main-seqg..w:bjebwf es 3aa68uence stars are colored blue, orange, red, and yellow. What is their rank from coolest to h sbbg6fewe3. .a aw:j8ottest?

  A Hertzsprung-Russel/,wbck 7p itk6ec0j)k l diagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sux41rcjnt x,8 r-o :oz9 xi;zitn is about the size of

  The Chandrasekhar limit of stellar +xmf+6j kq4vomass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is m+4j k+oq fx6vM, about

  Supernovas are thought to alwo3mb;4 lz do.tays result in

  Black holes

  Pulsars are rapidly spinniil u83dzj ri9nk.czr, y46ev- ng

State Einstein's principle ofk0,e awqd9ph0u2ag ooqi3 6h4 equivalence.

  The Schwarzschild radius of a black hole is that radi2y( bw-oox63 ial :pn npbbo06al 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 publis ywan:bli-36b6(op0x o2on pb hed 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 source05 yfgufgwyi 5bz,d6/ emits light of a particular wavelength in the visible, and the source is moving away from us, ,6yzf5b/ygi ufg 0wd5 the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of abx ce. 0yl(d,ieout

  The Sun has apparent bri-e aumrnnk 7:2ghtness 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 tha,dssr(w sog2,t 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 tog82mug9 ,1z lomb*p 6wzr ,xa 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 3hq bbs74voa2radius 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 Earth's nearest /tyj*fj* hhc96a q0km+0o+0nxupuw ystar aa0t 6kjmc w9 *hjfqy+ +yuu0*/n0ohpxt 4.3 ly?

  The apparent brightness of8z -yy;sa p xggz;jbekyl- /)9 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 g:ggsfdf5uc9ke*gv*b2 f)c5 ( + mvcpthe approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age o c gf:+d 5fb pfkg( ev*2*)cgusmg59vcf the universe, in years.

  If a galaxy is moving away from us at 1.0% of the s h ;fnt6oa5+yipeed of light, how far away is it from us?n ;aty 56ofhi+

  Estimate the speed of a galaxy that is 10 billion light- d8w c0.g*neasyears away.

  Estimate the observed wavelength for the 656 nm line :)kc )mv6 ifvhin the spectrum of a star which is 100 c: hv6f) v)mkimillion light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 10-ufo7wpldb7p7 *tx a1 :q 6hd./rji qu13 K. What energy (in eV) does this correspon:fbw*-6ap7uuqd1 o7dh/p 7xt.i l rqjd to?