The appearance of the great range ofwfhpp1x7y4 *l brightness among stars is due to

  The absolute luminosity for most stars depends8kvkqs .k* s5al3ah v(h) yg i.4cmav9 on the

  Four different main-sequence 5e4kvtb)hg zeq+s 6/l amik5 ;stars are colored blue, orange, red, and yellow. What is their rank from coolest to hottesz55e;gqkbvsil+/)e 6 m 4 ahtkt?

  A Hertzsprung-Russell duf2 p*ktt d2o +2.jezkiagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the sim g4 86xmb7nr*ppq8 yrze of

  The Chandrasekhar limit of stellar mass (below 3+,fjkk eihv)rcqw m8fbzk q(l0 b05:which a star will collapse into a white dwarf) is, if the mass of our Sun m( fvhk+,j8b:00 5k zrlc qwqf ik)eb3is M, about

  Supernovas are thought i: hd0n 9ybty+to always result in

  Black holes

  Pulsars are rapidly spinn+et; wix-fv( ding

State Einstein's princi4. ndp-*;yvak4so mvfple of equivalence.

  The Schwarzschild radiuykui85rfo ;o9sd ; c1n-mt4yxs of a black hole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einsf5 myy;oic-x drt9;81ukn4s otein 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 visib, pi 11qkvosv)le, and the source is moving away from us, the color of the light app v,p1k1vosq)iears to us to be shifted toward the

  The cosmic background8,o+w oxwvux8ks*gc8gd b dg 2dk(sp0jd0m () radiation corresponds to a temperature of about

  The Sun has apparent bright ll02 1; l9y*v2m6nad fxbrr plw3lt1yness 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 lumid x48xckt(*wk z3)3f qj7hptbnosity 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 radius of2kn8ek :/ijjhw 6c 5zq $1.5 \times 10^{8} \; km$. 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 m y/i7cl/ gv7gbean 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 anwaxdz51 u.4 qc4; mmxhgle for Proxima Centauri, which is Earth's nearest star at 44q.mdm;1 uxw c5 hz4xa.3 ly?

  The apparent brightness of a s7 y+fqi/ y6qz7yez.gz d9upd 0tar 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 c9,awue ,4a 3day: pdpapproximate age of the universe is 1/H, where H is the Hubble constant. Tak4dp,:3 ap, w9aedyucaing 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 thqpv:q7v4bbbo ywd9lop7z 8. 3e speed of light, how far away is it from us?bvob v yw: 4d.p789zo l3b7qpq

  Estimate the speed of a ga pg(uey/wb.7 ccx 3c sbeym:/)laxy that is 10 billion light-years away.

  Estimate the observed waue1hgyq yb2x 6u7l55n velength for the 656 nm line in the spectrum of a star which is 100 milliob 1un55heygyxul6 q2 7n light-years from us.

  About 1 ms after the Big Bang, the temperature of t6niaj 7el3 /.ymk.fzy (vv0pyhe universe was about 1013 K. What energy (in eV) does tf enl a3. iv v7ykyy0.6/(pmjzhis correspond to?