The appearance of the great range of brightness among scf*8h3gn 6w vyzd mg90tars is due to

  The absolute luminosity for most stars depends on theylab.3 iu;gjnbvd2fc+/ f:y ,

  Four different main-sequence stars are colored blue, orange, red hjo6sgzot33n,pll :/-gj :sp , and yellow. What is their rank from coolest to/l6 zop3nsj :3-, s:pthoj ggl hottest?

  A Hertzsprung-Russell diagram s;dr f8la 2xhqs:5f;ucrf e7z+hows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about m u (r+;9f-y k 9mqm m)fxxx3b(b tp5spzyfe.-the size of

  The Chandrasekhar limit of stellar mass (belolmz)mi *mcua*1 nfx,8w which a star will collapse into a,* c1fi*8a)zmxu l mnm white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always r )hfwu9:txe:yesult in

  Black holes

  Pulsars are rapidly spinnin0m ia zm./)rwo+,ei s4yrhqm a:-+ kqqg

State Einstein's principle of equivalence.9 +kpon,oe3 xt

  The Schwarzschild radius of a black hole is that radial distance from the ra* 8xnf:ix)pf/a b3w*p8tk kcenter of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his generf iap rpxbwt*x8)*nak: /83kfal 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 wavel; b hfw6qj/n/gength in the visible, and the source is moving away from us, the color owb;g hqnf/6j/f the light appears to us to be shifted toward the

  The cosmic background radiation corresponds a:rpei nha0(3 to a temperature of about

  The Sun has apparent brightness an ya.vc 4or;t.t 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 :(5,kohl pkreequal 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 ru f5t*u18p yq6*ew nmjvp.e5x 6ru4fsadius 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 m5b phj7b(q5xmean 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 Ckx2ms9k; td c6entauri, which is Earth's nearest star atm;296sxkk ctd 4.3 ly?

  The apparent brightness of a star is0u4x m05qqo3tre*pfc $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the afk 5ft h3;o-aypproximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 ho3fy5tk fa-;km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving ;8pspzu3s1-s: e zlnv away from us at 1.0% of the speed of light, how far away is it from -spz:;v eps1 nuls z38us?

  Estimate the speed o n;ex/ ebq)i3t xpezb;n,d* a8f a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectr3zp6e 5dq yx7wucqqmgg . 1r/0um of a star which is 100 million light-years from us0p/zq gr 1md5.6x weycg3 7quq.

  About 1 ms after the Big Bang, the temperature of the universe was about 1kzqy :h* sw ./.udswqt4-vha)a. je 8u013 K. What energy st /u vhaqw .dw )y.uahs-k8:jqz*.e 4(in eV) does this correspond to?