The appearance of the great range of brightness among star-j)qd3u-iilf3y l(xml2 p th8s is due to

  The absolute luminosity for most stars depeh5.gv8zk qe +knds on the

  Four different main-sequetzhg7/ 2 hgcjzm+rs(*aax,/ ince stars are colored blue, orange, red, and yellow. What is their rank from coolest tj2 hgaxgmric7/*/zt hs,+z ( ao hottest?

  A Hertzsprung-Russell diagram shows stars on a plot bfdn.kdb,ghx,4.5op1 )zho tof

  A white dwarf star with a mass equal to that of the.y wtqf fg 0udy-e r1mwep-)8; Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collap :3sfbt39l hh88qjbq vse into a white dwarf) is, if the mass of our Sufb s hv:th8q83l jq9b3n is M, about

  Supernovas are thoughty;ne4hk ,(wnt to always result in

  Black holes

  Pulsars are rapidly spinbr -add(bu84 fning

State Einstein's principle o vglz65 brz)7d,- l) t*fyzmtdf equivalence.

  The Schwarzschild radius of a black hole is th .(cu*wie;puf at radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativity theory. It can be calculated from a cpu(*fw.iu e; 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 . pexusd j.c:3;i1 g7eycr q+ga particular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to b+i jygp :xdq;.scg e.ec 71u3re shifted toward the

  The cosmic background radiation correspondsb: /r.m( ufvko7-6qcc g(cm.jc* teib to a temperature of about

  The Sun has apparent b :l(jqsflo*.prightness 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 lumino qvl)*8;zp64ou(4d x*skhg -b osq qybsity 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 hafd+ 9ls o2c)2q5ozz cyqqm a78s a 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 ctr7fs :gk1+i accv(7 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 nearest stlqrw w;4;hbmk5 nnyy h4e q(43ar at 4.3 l(ylh yq nww3qm4; 4ne4;r5kb hy?

  The apparent brightness of a lo4c 4l6e kq;cstar 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 the1+iwuo x0vz6v approximate age of the universe is 1/H, where H is the Hubble constant. 60+vuxoz 1vwi 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 of lig3)ob ctkclm,hd0) oc )ht, how far away is it from u0c k)otmc )bh3)dlo,c s?

  Estimate the speed of a galaxy that2.wme v5y ba-c is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum vc(bbb* i08mfof a star whmb0* bvc8ifb( ich is 100 million light-years from us.

  About 1 ms after the Big ys9y;d8+ uvhv9;onuk Bang, the temperature of the universe was about 1013 K. What energy (in eV) does vyvd +koh;u9su;89nythis correspond to?