The appearance of the greatt)mx3 yy* 86y8ge 9f hikwoelh 7mg/y- c4h4cd range of brightness among stars is due to

  The absolute luminosity for most starshx1 mz0:db-nmzw: +us/.q h4s ysb 8iz depends on the

  Four different main-sequenwe ls3 7yip3,z9ivop(ce stars are colored blue, orange, red, and yellow. What is their rank from coolest to h9p3p3 w( eo7,isl yivzottest?

  A Hertzsprung-Russellu1/ +g3xqwo el diagram shows stars on a plot of

  A white dwarf star with a mi ffejq.6. ,t99+nbz(spsfcm ass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will coll, vl).-sh; p f9)xsu7m cdqnuvapse into a white dwarf) is, if the mass of our Sunuxv)sqm f uhl.9p;)cv,d n- 7s is M, about

  Supernovas are thought to always resuepn:st5s yb1nfsu3s )z2j9 q/lt in

  Black holes

  Pulsars are rapidly spinnglq7s7kw7( r uing

State Einstein's principles:2e.xrfj j;+er u :yx of equivalence.

  The Schwarzschild radius 4fep7gl7fsi56fcyk w,+l .w wof a black hole is that radial distance from the center of a sphere within which not even light can escape. It was first dis 5i ww6gf,eckylf.l w7s+f 7p4covered 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 particn;g-sok.d g6ogg k- b3ular wavelength in the visible, and the source is moving away from us, the color of the light appears to sg-d;3g- . 6kogknobgus to be shifted toward the

  The cosmic background 9fpq8c3)k tq5 o/rnyoradiation corresponds to a temperature of about

  The Sun has apparent brightness at s */e a++gva0p4ihc kxEarth ($1.5 \times 10^{8} \; km$ 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 S7*ubxy em(i- c3+avs;lur .jl6 dt)reun ($1.5 \times 10^{8} \; km$ 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 at-3eh2js *k6 muruui xmx.(1l 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 radius a84xkl )f3am bxf)ob2of $1.5 \times 10^{8} \; km$. 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 Proximr8 cge4/sznc 5f61f mya Centauri, which is Earth's nearest star at 4.3 4sffc/65cz 18em yrng ly?

  The apparent brightness of a star is p takko,t)sz /z0,og($1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universe is 1/H, where H is theghgpfyz :.0(n Hubble constant. Taking H = (g ph:y fng0.z20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speev:2e:egbubn/:f a u6:t- koq*s )rg1r gxnr o3d of light, how far away in:) q -nk egouvof3 6ba*t1 2gs/:xe:gbrur:rs it from us?

  Estimate the speed of a galaxy that is 10 billion li );,p0u0uog bx4trx patrt x5/ght-years away.

  Estimate the observed wavelength for the 6wufr 5cf. s(l-r (-ftn56 nm line in the spectrum of a star which is 100 million light(t5fsnc w r.fluf (r---years from us.

  About 1 ms after the Big B;hwz*k ffex0 -ang, the temperature of the universe was about 1013 K. What energy (in eV) -;0z f wxeh*fkdoes this correspond to?