The appearance of the great range of brightness among stars is due t9nii0vpts*s3 o

  The absolute luminosit ns cxcma7uyrhq6q 3/qz)5m-(y for most stars depends on the

  Four different main-sequence stars are colored bmfkzrefy ;mu- 2kn+ -:lue, orange, red, and yellow. What is their rank from coolest to +me :2u; z-rkyfn mkf-hottest?

  A Hertzsprung-Russell dig8(,z x9f+d. 4rnr txhq 7nrpbagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun+:+)bobqvpbg- tn:a m is about the size of

  The Chandrasekhar limitgg7xw+m+-b4)lqoog2xws /vs of stellar mass (below which a star will collapse into a+s/4x)bv o -wlgs+mqogg27 xw white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always result ip lizb,m)jvq-a1 +uigrx, *,w n

  Black holes

  Pulsars are rapidly ssonw)0t7bw2m3 alisxh ru8)) pinning

State Einstein's princsc9wnyyzk3 : :f yvth60epy(pg5t0 p2iple of equivalence.

  The Schwarzschild radius of a black hole is thamx2e xlcu.n7 .t 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 Einstein published his general relativity theory. It can be calculated from a star's mass M x.uc2xn .le7m 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, a6:oh6lz kh26+9txyoposwn ( i nd the source is moving away from us, the color of the light appears to us to be shift9o66 t xi n(op:h yh+6z2okwsled toward the

  The cosmic background radiation corresponds to a temperature of aboutznts)*i2yr , x

  The Sun has apparent brightness at Ee i03oops m+z v0y/bi1(pye c,arth ($1.5 \times 10^{8} \; km$ 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 lumgh s(pst :)3aminosity 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 meang01bidhgj6,4az 9peta)/ 2 br nktzj0 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 radi2 y :ezoephi36us 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 Proxiqhb -y1l (wwp1ma Centauri, which is Earth's nearest star at 4.qwyh-(l 1pw1 b3 ly?

  The apparent brightness ofy8eyv 48:lh fe-rf1rm 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 is0db 5l 4f5kegm 1/H, where H is the Hubble constant. Taking H = 20 kml mkgef 5d4b05/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving awm qrxi5-d a(./xlxex7ay from us at 1.0% of the speed of light, how far away isl5q(xaxx/ri7.-e dmx it from us?

  Estimate the speed of a galaxy that is 10 billion light-v7cvce y) 3.we+ g:rjoyears away.

  Estimate the observed wavelength for the2c 3ll2sf ck+j 656 nm line in the spectrum of a star whc 2l2f+sc3jl kich is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperatu (j yv(jke tp/kcz8df9(1ns6mre of the universe was about 1013 K. What energy (in eV) 68ndskvje(p 1z/9 f jmty( ck(does this correspond to?