The appearance of the great range of brightnesg4i 2rznw3ctu4:dvi+s among stars is due to

  The absolute luminosity for9*,1kwjtwdqr42z n0azk k-ra most stars depends on the

  Four different main-sequence stars are colored blue, ora0x . lqkdq2l+knge, red, and yellow. What is their rank from coolest l0 xkk2+ql.dq to hottest?

  A Hertzsprung-Russell diagram shows stars on a plottzv:( h:wvar (.v,w jxwmadtr,c v4,+ of

  A white dwarf star with a mass equal to that of the Sun is about to :60 (rdd0f9h ,4hdihe ng+kuar ws5tn.onm /he size of

  The Chandrasekhar limit of stella7 /kupe4 ysuho,z;v 0;xay8c qr mass (below which a star will collapse into a white dwarf) is,kx /8eq,;4 vyazhy;70s o uupc if the mass of our Sun is M, about

  Supernovas are thought to always result: xwj,t3u zur3 in

  Black holes

  Pulsars are rapidly spinnu/g5l .uhkgdb);90 xkhbe 9vging

State Einstein's principle of equivhcy )ik: ,3)j/ds meicalence.

  The Schwarzschild radius of a black hole is that radial dist;m rhzk .hygm:z g)soh)e4b a9f; xi24ance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzscgh;z9 fhh yr.ib4; kzmsoamg) :)x2e 4hild in 1916 after 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 of a particular wavelength in the visible*e-sq9qfhy0fey ) q60p5zg xp, and the source is moving away from us, tzx5) 6ey p00qgh* qq 9fsep-yfhe color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperaturx, cem6w)f) d80 fha/moo0pltla: f .je of about

  The Sun has apparent brightness at E me75: sgc7ltxarth ($1.5 \times 10^{8} \; km$ 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 luminosidmatvs(206:d lt ffp8jadd*dggo 9 z:*i9sx4ty equal 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 mean ra6bp(q(cvdi:; jpo n. h-8fxa ldius 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 radius zp16y)qg3 a gz 2cl8chof $1.5 \times 10^{8} \; km$. 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 st,k;io06sdt q4vq v-la qx5 rq ,wssh4)ar atkt 4vr4 0d)s;ivq, aq o5,x qsw6-sqlh 4.3 ly?

  The apparent brightner g8if )6awd3rss 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/H, where H is xhev9u8r+ia/the Hubble constant. Taking H = 20 km/s/Mly, estimate tha9u i /vhexr+8e age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the spe:5vhed sx9:vved of light, how far away i vsv:vh:95dx es it from us?

  Estimate the speed ojxgk/+- bc,t/it dov9f a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the ol,n .wr1 fc2ispectrum of a star which is 100 million light-yearscf. wi2o1rn,l from us.

  About 1 ms after the Bz;q z qho,,yt,f7flp1( utd6a ig Bang, the temperature of the universe was about 1013 K. What energ ytohz,fu (qaz1,6 pdqtf; ,l7y (in eV) does this correspond to?