The appearance of the great range of brightness among stars is due tmn*.ecbcc3z8kc4a, qxk 3m)go

  The absolute luminosity for most stars depends oe by 4g(p e*fvpzg:z.4n the

  Four different main-sequence stars are colored blue, orange, red, and yellow. rvu 9n(2skp to h2f6gnr5(y3qWhat is their rank from coolest (yqp vfr r9stu3 n(hg56n2ko2to hottest?

  A Hertzsprung-Russell diak1a uum ln/1jbk 2r+-: yq2hasgram shows stars on a plot of

  A white dwarf star with a mass equal tn(y.m ps147ykbo 4fhg o that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a starnf8 mipiro2; 4 will collapse into a white dwarf) is, imn4p8;ifi2 rof the mass of our Sun is M, about

  Supernovas are thought to always+:a7 ) ikh9taby z.nqt result in

  Black holes

  Pulsars are rapidly spinrc iqzmpz678 u*,r ;0xcmp5z+(;6zqfk ukko ening

State Einstein's principle of equ(eso xiyb88j 3ivalence.

  The Schwarzschild radius of a black hole is that radial distance fros )km+84 * i/ tra(zivtyt4g( sd(kbcom the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einsteis z y/)*miis k(4gvkob t+ ad(48(cttrn 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 4qq)wj-j jhid1dm,-zlight of a particular wavelength in the visible, and the source is moving away from us, the color of the light appears t-d)i,qwhj4jdm-1 q jz o us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of about.x4 x26o uzcyp

  The Sun has apparent brightnessye393v ip t(imu,vd.y 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 sj8h5rcri1 bfc x(pk ,:w4qtr q3 6or9that 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 radiuyjy;jb( lb9b 0q6f7ahsl)7mws 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 ha)e*,n z z wq/seac3axt7v:/fds 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 Earth's nearest st4ua.unbo (*ppg z-)uj ar at 4.3 ly?bu pzg)uo4* .p juna-(

  The apparent brightness os:grk ;(kvcnwr -oo+ +f 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 un;. ibyrs v7l.z7d5kqn iverse is 1/H, where H is the Hubble constant. Taking 7sq5r n lvb.7dyiz.;kH = 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 far aabc)r zqoio q2u2 mvpl/22j.8way is i ujba2)zv/rl c2mq. 22q8ipo ot from us?

  Estimate the speed of a galaxy that is 10 billion ligh ebkb8 4ts1mykyg82ytedm-qy;.mw1z3b t10nt-years away.

  Estimate the observed wavelength for the 656 nm line in thea *gpy g)617(fmaelrt spectrum of a star which is 100 million light-yearsg(l1a)6ypg* m7 er atf from us.

  About 1 ms after the Big Bang, the temperature c:xfmql :52s -v* v1njyhyr.pof the universe was about 1013 K. What energy (in eV)5jply2yf hv:1qn.*-r xm :vsc does this correspond to?