The appearance of the great range of brightns4kqq z/, (bcdess among stars is due to

  The absolute luminosity for most stars depenc5 2ym8zu: mh d6dh,1ce(*. pfc hxvtbds on the

  Four different main-sequence stars are cu uq vw/j6qu-xsm3)s : l)/c )o,vecwvolored blue, orange, red, and yellow. What is their rank from cos -o 6))/c,wuvjqu:u q lcw)s3ev xm/volest to hottest?

  A Hertzsprung-Russell diagram shows star )hrvfqvt8j2)(u8- yw0flmt)h1wg w 4 yjc7mns on a plot of

  A white dwarf star wi2wvot*u i:u)a th a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which 6)q tow uu3bs9eue;.m a star will collapse into a white dwarf) is, if the mass of our.;uw)uus6em 3bq 9oe t Sun is M, about

  Supernovas are thought to always res7;+dvy 7ozw*xdwh,hlqbb1 h) ult in

  Black holes

  Pulsars are rapidly spinning o618h n+afszp

State Einstein's principle o27o wpsa az-7pf equivalence.

  The Schwarzschild radius of a black hole is that radial distance from thefu 6tm02jki1et , twl*m.gkpfj35y;n center of a sphere within which not even light can escape. It was first discovere u6t fmt gp 0.*ke;5jtf jn,w1il3y2kmd mathematically by Schwarzschild in 1916 after Einstein 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.k d -ib i(pco4v;pex( the visible, and the source is moving away from us, the color of the light appears to usok 4(p-(dbcev; x.i ip to be shifted toward the

  The cosmic background3 ty+.w 4bntziou)1uc radiation corresponds to a temperature of about

  The Sun has apparent brightness at Earth (:nxekt; -g p.q(vta ;f$1.5 \times 10^{8} \; km$ 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 the Su2zu *r/4h ywyd;c7// tzbjoyu7maw9 ln ($1.5 \times 10^{8} \; km$ 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 rain1-: wk fu21dqb k3j8xyoc 9gdius 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 rk v ied (ry25zmaggw;6x4y2 1radius 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 Centaur.wu s u7ao3u4u1 imf.wi, which is Earth's nearest star a7.u1m sfwua.u 3oi4u wt 4.3 ly?

  The apparent brightness o9v.*vi lifd:xg7+gsh6by 4 aay 0bnq2f 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 is 1tf2:m.mc( nr oshg79q/H, where H is the Hubble conshgofmt2sm. 7 rq:9(cntant. Taking 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 the speed e*u0nf u69 +p* qf9fcobcvd0+ w8mjlu of light, how far away ise+0pu jfbf*odl0ufw96n u mvc+q 8c*9 it from us?

  Estimate the speed of a galaxy that is 10 bill);/(kxzu fsf jw; x9awion light-years away.

  Estimate the observed wavelength for th e q,qy/2gi5ake 656 nm line in the spectrum of a star which is 100 million liq ae52/ igkq,yght-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1n3-39 n4spz 9al qgiee013 K. What energy (in eV) does this correspond to-aqgn49ee9 zlp sni 33?