The appearance of the g +yb+hm i s/ubei y9)epiw.u41reat range of brightness among stars is due to

  The absolute luminosity for most stars depends on themb(h3v+62e dnp qd)o l5wsho5

  Four different main-sequence stars are colored blue, orange, o1fid6lhx ,155ytmts red, and yellow. What isdi f65,y51x1otl smht their rank from coolest to hottest?

  A Hertzsprung-Russell diagram show urixv8r26d4g9 3 oiam7up l6js stars on a plot of

  A white dwarf star with a mass equal tcw fmdngkc y(q-2 5rn3: ;duxwu2z4m/o that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star(unqk* iwn 5y9 will collapse into a white dwarf) is, if the mass of our Sun is M,*q(u9 nknwiy 5 about

  Supernovas are thought to alwaok0 b/ wzqf8wq wttzt(b 9i2.ftys6.*ys result in

  Black holes

  Pulsars are rapidly spig//j swem1zp*7pkc gj,,+lfbnning

State Einstein's principlvuykizl/502:/ tdm eo e of equivalence.

  The Schwarzschild radius of a black hole is that radial distancp. m9zh lt(-axp: am/p1(gyyle from the center of a sphere within which not even lip9:-t yaplm (.hyz (g a1xlp/mght 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 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 */dryr4uu c*ylight of a particular wavelength in the visible, and the source is moving away from us, the color of the light ac 4*d*yur ryu/ppears to us to be shifted toward the

  The cosmic background radiation correspondsv yh: a)6z;csc(h4eni to a temperature of about

  The Sun has apparent brightness at Earicj7kx b+zp;+ th ($1.5 \times 10^{8} \; km$ 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 tt m-7.*uyhdlno 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 kgei.fj,bkv dn8 06s 3radius 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 k7n,;blub4iezqom 1h 7ic*z :h oj; )zmean 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 nobcdyj77ky 60 earest star at 4.30bod 7cy6jyk 7 ly?

  The apparent brightness ounzkzra ,*r uy. l9:l15 bakwa hs05rjb:as13f 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 unlc 47wjxo2;bgdr1: the approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/w 7dou x2 r;:jl4c1nbgMly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of li;fny(p) tn0cu0m z-ois)ugcjs. *9erght, how far away is ic(srys u. c f)tu0*n;je-) zgp0i nm9ot from us?

  Estimate the speed of a galaxy that is 10 billion light-years n3xwy:*y a- h,hawar2away.

  Estimate the observed1u0 8 (xdhlz rrxdth(0 wavelength for the 656 nm line in the spectrum of a star which (0u( hz xd hx10dlrrt8is 100 million light-years from us.

  About 1 ms after the g).b(h l cpn4rr6n;n6fgcu6t Big Bang, the temperature of the universe was about 1013 K. Whrl)b u(g;np46nhfcrt c .6g6nat energy (in eV) does this correspond to?