The appearance of the great range of brightness jkf/ y9f jr)qh98dvh7among stars is due to

  The absolute luminosity for most stkbnuzp/) *c 3u mvj /llrx9 ;g/m*rp(bars depends on the

  Four different main-sequence s n*qv8ujk14f 5 m-scrs7eod.s tars are colored blue, orange, red, and yellow. What is their rank from coole.d-k s51 f874mjcsosqrnu v*est to hottest?

  A Hertzsprung-Russell diagn6m9rw;xy ce1/hk0rebweks .pr* , a+ram shows stars on a plot of

  A white dwarf star with a mass equal tda(zd :l1(jce o that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below wh2-txvv3 6ai 77wm0ksnk niaz1ich a star will collapse into a white dwarf) is, if the mass 6vna7 1nzs m2tx3i ak ivw0k-7of our Sun is M, about

  Supernovas are thought to alwaysqqv /:g0czebe s4z,ozmq87 e 5 result in

  Black holes

  Pulsars are rapidly sbe /gli2 tm ppk-9dyq1cas.* +pinning

State Einstein's principle of equivalencs sgzgmk .hy*u+44al5e.

  The Schwarzschild radius of a black hole is that radial distance from the cwmy5,j1 w) *u6drzm gyenter of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general w zyd, gu*mrjw5y61 )mrelativity 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 vis:6 yrzwrcub31w(/fw rible, and the source is moving away from us, the colorw:3/ ( 1wwfr6c uyzbrr of the light appears to us to be shifted toward the

  The cosmic background;jg d6l79 hsw4 )*qe(tqosnu r radiation corresponds to a temperature of about

  The Sun has apparent928vj m9-5cc0h,i8zy:vqdf p 9fiqp(rug wgk brightness 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 /dd6k q5hb;cj+eu z,jequal 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 ok4c jn4ty(bhufo .zqb*jo 8/1f $1.5 \times 10^{8} \; km$. 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 meana) pcbk *a4agz(* ;yln 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 n )r8e9ldvw.sbn 4l, hbearest star at4hbvw8r,bd)l nsl . 9e 4.3 ly?

  The apparent brightness of a stapn:q wbqg9 4-ir 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 ( x2) lf4fuhmgtbs/i4of the universe is 1/H, where H is the Hubble constant. Taking H = 20(tbs 42fmgfuihlx)4/ km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of thews;y m/p+)ui6( ghcid speed of light, how far away is it from /c6pudg)m;sh( yi iw+ us?

  Estimate the speed of a galaxoto5dn9rgfl515cec 2v;o; 8onb;t ar y that is 10 billion light-years away.

  Estimate the observed wg 2y2- b:iiilpavelength for the 656 nm line in the spectrum of a star which is 1-gi i i2:ylbp200 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the univer h-e-p27r rkwvjirx*1 m,xv8n se was about 1013 K. What energy (in eV) does this correspond t-iv*jxxepwn,r 721 8 mhk-vrro?