The appearance of th,a nv u7udq ux,7a(t8ne great range of brightness among stars is due to

  The absolute luminosity for most stars depends on tm d;zs7,o,xqqhe

  Four different main-sequence stars53 pg3nwbb5hkauc3 h1 are colored blue, orange, red, and yellow. What is their n3h wgbh33c 5u51bkp arank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot o( ozy/ wieq*qt2*e)fof

  A white dwarf star with a mass equal to that of the Spzcsk(py x/2vz6*; n xun is about the size of

  The Chandrasekhar limit of stellar massgebrh *,;thi)odw y5 9*eosk) (below which a star will collapse into a white dwarf) is, if the ogtd5ys*oe9k;*),r) wb ehi h mass of our Sun is M, about

  Supernovas are thought to always resultq2p+.jqeih*ny l d /p6 in

  Black holes

  Pulsars are rapidly /h *k;9fl p5vgo.yonkspinning

State Einstein's principle of equiva ml6 yv05ea a:gux4m5t,kjri(lence.

  The Schwarzschild radius of a black hole is that radial distance from th 7u//ep5kewu dw9g;hvc 0 wdpcw )g7*ke center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein publishe9u7 cdewcgk;/w/ *vw ph)udwe 057kpgd 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 the8r8 -+b gnhyqi .r1(7p.1afkiwpr )by sbs7ov visible, and the source is moving away v1sb7h)( k fr.ayip1+ rn b7.qwi-r8sobyp8g from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature ofwm ob,db2,3 7hzs2own about

  The Sun has apparent brightness at Earc+rvm. zmamz +1;r 2+fbde04f l-, flamg x2kwth ($1.5 \times 10^{8} \; km$ 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 eqluez *thm,+)aual 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 hascfj4izwy :p6 5zi 9xk( 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 a1m-c en)q;y .rlsk* pw 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Cen2 j;*n :d j mxsei2nvgf7v,8prtauri, which is Earth's nearest star at 2gn*ivn, 7m2sjr8d ;xefj: pv 4.3 ly?

  The apparent brightness qhdjt. vum80-di 1b+f31 mkuf of 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 1/H, wheretp ebp 1h(6 )6ps2gmif H is the Hubble constant. Taking H = 20 km/s/Mly, estimate thepp21)bf ge t ms(6ihp6 age of the universe, in years.

  If a galaxy is moving awayk(sr :hl6mt.y;:eww)* m *ipolo0zah from us at 1.0% of the speed of light, how far away is it from rk)ti*:aoly.plo(mz :h*sh 06w ; wme us?

  Estimate the speed of a galaxy that is 10 billion light-years fu rg1y0sb;71mz /ysy away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of ,pl hig2 kfzfrh7.dq(q; a z57cao95y 7uese2a star which is 7aizuh ;2o5h,5ek7fgseqr l. ya9 (d 7czfqp2100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the )al.nolnalo*dp 2 7 8qr5 5tmzuniverse was about 1013 K. W a5alqdr*. 2 tl 8lnooz)nm75phat energy (in eV) does this correspond to?