The appearance of the great range of brightness among starsjfp(pfl 3jras *0j5t7 is due to

  The absolute luminosity for most stars depends on +/g phi.qpxl. the

  Four different main-sequence 3sai iqk-1 rbui0k f5*nils*o6 e3nfxgpc6 22 stars are colored blue, orange, red, and yellow. What is their rank from c 2 asi*uqr 30klxob*ic-62nenp 6i gi 3f15ksfoolest to hottest?

  A Hertzsprung-Russell diagram shows stal x dpx.0njq-e( 2y.lzrs on a plot of

  A white dwarf star with a mass equal to that of the Sun is ab8*nuz+jm 8) dchf,x0j3cndytb4 w ;hbout the size of

  The Chandrasekhar limit of wn4al-3z qly *e lp,(zstellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M, l3l4qypzw*- n(,zl eaabout

  Supernovas are thougw*e1*.g enla l77nqj fht to always result in

  Black holes

  Pulsars are rapidly sthun3n*idq5o ed vwp4 8n8(*np: ; ynhpinning

State Einstein's prin3 ot) *he myv.o,ilk6jciple of equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cente;nui, r grn4tjj+u6x -r of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild 6 rjrtjnu+xn4g-u ;,i 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 j/ ta8. *z biu2n-m mu*n,exq1klkhs4 a particular wavelength in the visible, and the source is m/28i. k nu1abj eu-qht4,xmkzmns **loving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to ,rpnet aiw-(:a temperature of about

  The Sun has apparent brs xrm kw :,0c9wtpu2+:o f8issightness 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 luminos .t0*fou z )xfjwvchuw3/39cgity 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 bqsgi -6,e/se2os 5dfof $1.5 \times 10^{8} \; km$. 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 radiuskbt92y9k1:qd( db+zge q;eksk: t hw, 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 Centaunbnegv8 co0-9 ri, which is Earth's nearest star at 4.3 cv-n8 9bn0g eoly?

  The apparent brightness of b7d*zu0nu rx*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 unifvim0ghtp ka)s4( so :7.m6f mverse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimatesf4hsofv067 t mm.k)g(m api: the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far away z)idtqqa9uo wul.qgu570, a/ is i0u,i5ozaqal qqu )g7tu 9./d wt from us?

  Estimate the speed of a galaxy that is 10 billion light-years 9q5q s -ov*vgaaway.

  Estimate the observed wavelenyp 3)jpsx2 tnvb(*z y3gth for the 656 nm line in the spectrum of a star which is 100 millioz (x3yyt3sjbv2*p) np n light-years from us.

  About 1 ms after the Big Bang, the temperature of the unsd gv/go.pw0,pdiivn v*if 2 8i24au*w/akv- iverse was about 1013 K. What energy (in eV) does this corresvkwi *dvg8dsouif /0i 4, gi/ aw*v2vnapp 2.-pond to?