The appearance of the great ra40w y/yn)e7oc k7zdvk:.y0 f+zbbk qknge of brightness among stars is due to

  The absolute luminosity for most stars depz ouela)8y :v bz69ui+ends on the

  Four different main-sequea6rz74our5t ence stars are colored blue, orange, red, and yellow. What is their rank from coolest to hottes5t4 arrzo67ue t?

  A Hertzsprung-Russell diagram shows stars on a plf++rs6l 3 r)f4pyxz t6snl u)zot of

  A white dwarf star with a mass equal to that of the Sun is about the size ouf5bh zc 80bbzri7l7 (f

  The Chandrasekhar limit of stellar mass (below which a star will collapfyn5 b (3rb j5y) 4nyzcqlyg98se into a white dwarf) is, if the mass of o9g48f(byn5bl c 5nyj) yzyr q3ur Sun is M, about

  Supernovas are thought twcl+ zy+z-rvb34 t7m 69t jw0y4 x(w7qrtbjmso always result in

  Black holes

  Pulsars are rapidly spinnizb5w0dka w0*-r g km:vng

State Einstein's principle of eur po5ng.ll 8hc hi4)0quivalence.

  The Schwarzschild radius of a black hole is that radial di.qou.h9lslc 0ww; m -pstance 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 rlowm h.0w 9u-;sp.qlcelativity 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 visib53vf 240 fgga8ljfabk n*buw boy5.4ble, and the source is moving af g bl0a4k58fa2 .bnfubo4w *b3vyj5g way from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds ;qj((tv:hcsnl.0zr e to a temperature of about

  The Sun has apparent zmy 0;of /;,p6kxonlu 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 equal to that of tv)j9zo g.x/i bxp,y;p he 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 ha+a1wx ss8e8ucp0 )( ac kls9zfs 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 km?

  The Earth's orbit has a mean rad /cw;9 (8 -dowx,v a.nzz b3cdmgkkd8s2 bf3zlius 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 star a hu/1 e1wru;pxc(xam/ t 4. heu amxp1/u;cx1 r(/w3 ly?

  The apparent brightness ij +6qa:en:6*wkmb8jeap3g g1p k9i iw 6x(fjof 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 unive-1fp 8ex 4*f adkahzw6rse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in yeaah4xf - 8ke*wz fd61pars.

  If a galaxy is moving a(qxlo).( j yc4hn i3jlfeh+1d way from us at 1.0% of the speed of light, how far away is it from+.d (cllq(i j)xoynhjf41h 3e us?

  Estimate the speed of a galaxy that is 10 billion light-year5d00rr99kvhb jf uxt. h eo9dg*el97ls away.

  Estimate the observed wavelength for the 64w3 +s.l fmhjh56 nm line in the spectrum of a star which is 100 million 3shh. wflj+m4light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 K.b5wxa1wjiqpjw-2 sg0i2e(k b rp 3 0c. What energy (in eV) does r0p.i(aejp3w qc2 2b5-w w10 kjigsxb this correspond to?