The appearance of the great range of brightness among stars ihr+foj/zxv 26/:de ows due to

  The absolute luminosity for most stars depends tw(kr hjmi (h e9zz(v 8-dr7y)on the

  Four different main-sequence stars are colored blue, oraaxx4kgon-9r6t8 vb85 hx5fgrnge, red, and yellow. What is their rank from coolest t nfor x98x-5r685ta k hbg4vxgo hottest?

  A Hertzsprung-Russell diagram shows stars on a -2jp: (m n/xmuslpwqt9)3 7hy q cr(ujplot of

  A white dwarf star with a mass equal to that of the Sun is about the otzock 5sf1 mg,b-1q )size of

  The Chandrasekhar limit ,fgcs9rx8pohak :38j x :raz9e:bm1fof stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M, am zfraae:8ox9,jcs::x k 3hg8 r pb19fbout

  Supernovas are thought to always result e3w z5e(i 4jsf4ji:p0bzg ei3p0cvl5 in

  Black holes

  Pulsars are rapidly spinnj3)b j;k6bseging

State Einstein's principle o 1.rulabl3d7da -lzu 1 xk1va4f equivalence.

  The Schwarzschild radius on.z5 ::rnat d,dp;gvsz l3 a-hf a black hole is that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild i3z :azahv:dn-;rt n.p l5 g,dsn 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 wav3p6 abspo nt:4r+cc )celength in the visible, and the source is moving away from us, the color of the light appears s+co:6tap)r3p4c ncb to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of about2;p0r 41sv 5f)em/yv1 cdo7a yjpx ngd

  The Sun has apparent brfyp2ea 9k- i:g:j9)dc an k(jzightness 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 lumv8 qm1dno5nd6d o6mm,inosity equal 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 radn+*k ,rv5qaxl ius 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 radiuso9fa514tdja ysqob0 3 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 angle44e9 mh im z+xorgwca6( kzs41p-lv.a for Proxima Centauri, which is Earth's nearest star at r4iz 6 z.c p9mvmo a4s+xhk-law4(ge14.3 ly?

  The apparent brightness of a star d0j.+8hvwa0rgs9c qc 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 th;nr r*bklfrpv (sh7(g3 lhc1*e universe is 1/H, where H is the Hubble constant. Taking H = 20 p*cl;krv3fsr nbh( g17r*(l hkm/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, hs.)8bey+g ckmow far away is i8s yme) bckg.+t from us?

  Estimate the speed of a galaxy that innvcf0x ()/ nds 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in tqxx7i.it0;flx+6cwgg yjj1 7he spectrum of a star which is 100 million light-ig+qy0 xxiwj7 ltf;.xj 1 g6c7years from us.

  About 1 ms after the Big Bang, the temperature :k/mmvg(tvt q+o3wj1of the universe was about 1013 K. What energy ( v+t1/t:gjq3 mkwv mo(in eV) does this correspond to?