The appearance of the great range of brightness among starslce ht 25s;i8t is due to

  The absolute luminosity for most stars depe tn/0f0dzlyu /wp o./ry2;ovands on the

  Four different main-sequence stars are colored blue, orange, red, and f zfio.-u) xw6+c;t pv tgt0l(i og)u*yellow. What is their rank from coolest to h)fi-ofxt( l)v6t opg*t+ .wg0 uu; izcottest?

  A Hertzsprung-Russell diagram shows stars m v;*lz 0 r4t:wptf,xpon a plot of

  A white dwarf star with a mass equal to that of the Su( m0 pr dz+h/o3uxwzz+80wucin is about the size of

  The Chandrasekhar limit of stelll+2voi y ile0a/:ovy0ar mass (below which a star will collapse into a white dwarf) is, 0:2 ay +/ v0lveyoiloiif the mass of our Sun is M, about

  Supernovas are thought .d d98zhwj wvzv rfm:;iuts*q9r+ e:+to always result in

  Black holes

  Pulsars are rapidly sp re(jano7 b:;ninning

State Einstein's principle*xlnwf 2.5zsx of equivalence.

  The Schwarzschild radius of a black hole a*g,s pt5jlp70.r om qis that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Sch lg0qs,.tpr75p ojm*awarzschild 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 particular wavelength in gx.,8mttdbs l +h5tt8etal 7lt8jei 2d-y2c3 the visible, and the source is moving away fr 2mg8jixc htyttl-d7tee 882sbl , lt 3+t5da.om us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corp;ecs 7 (brwn;responds to a temperature of about

  The Sun has apparent brightness a9yvxrgt4kn+ - t 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 luminosihmd9;x n3*o- cht ki+t0 cg+vkty 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 radius of vz*e23g1qss(8 scdrg 9(+pext f)ssw $1.5 \times 10^{8} \; km$. 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 us 0f6(kpvb 2xz c,1j .px.jxra 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 Centauri, whidtt1 g;x-hi h/jw)c1 ftn9cz)p ul;d/;o:pi rch is Earth's nearest star atgwh)d)-;uc;flo /txzd;c tti pj:hn11 / p9ri 4.3 ly?

  The apparent brightnessp y5lh0bk(vfhhy ;-d 4 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, w sft -f5 a9-pgh1d5qkphere H is the Hubble constant. Taking H = 20 km/s/hq fg k5tf1spda-p9-5 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, how fahz aq:w 7p 4fa:;g r h;zsor5ze2zk3i9r away is it fromza h 7;rq w2e:3gz;irskhf 5z9:op z4a us?

  Estimate the speed of a galaxy that is 10 billioa5i;f1bqzzg0 n light-years away.

  Estimate the observes-.ouoq0i*8yjlv. 1mqp-, ccy , s ffid wavelength for the 656 nm line in the spectrum of a star which is 100 millionj plmoyuc . y*o f0.-fqcq vss1-i,i,8 light-years from us.

  About 1 ms after the Big Bang, the temperature oflh1b,y p3fndqvu8 *oe/kq: e0 the universe was about 1013 K. What energy (in eV) d80f, 1ke3o*n pbyv/dq: hql euoes this correspond to?