The appearance of the great range of brightness amiv 2ev6+5khz-ehpl v5ong stars is due to

  The absolute luminosity for most stax;p5wfdrt e-z:kp+ o0rs depends on the

  Four different main-sequence stars are colored blue, orange, rxr:ic4 9e8z whed, and yellow. What is their rank from coolesz4i9 hrx:cew8 t to hottest?

  A Hertzsprung-Russell diagram shows stars on d1dk ,k(tt; tfa plot of

  A white dwarf star with a mass equal to that of therm n5 e *7zjz+8.xsikk Sun is about the size of

  The Chandrasekhar limi0(sx2( s3wby +6q yamyj8mfyl 91y zjjt of stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M,20xbza+wj(f ysyy9ql y3ym m js61( 8j about

  Supernovas are thought to alw zi)u9 nte*vj*ays result in

  Black holes

  Pulsars are rapidly spinn+vpoe1dznmseon*5 nu 0z) pg-9s0v7j ing

State Einstein's principle of6srrd uil e6 4hvo,r+ *ls4ef* equivalence.

  The Schwarzschild radius of a xg awm if(/j4;black hole is that 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 4w(aixf;/gm jpublished 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 wavelenggcf6m i, g0l.ith in the visible, and the source is moving away from us, the color of the light appears to us to be shif6f.i ,gmiglc0 ted toward the

  The cosmic background radiation correspts+vdn;*za qdc* 7h u*onds to a temperature of about

  The Sun has apparent brightness at Earth/9cnc7oq8he v ($1.5 \times 10^{8} \; km$ 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 cabtjx*r w ;;u1mm3o:s3 abg*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 r+, fv;vy+ d cbjvz6m;tfco d*:adius 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 radixpl:,/fmtp mx3k 3) k dd,5x15s rynrrus 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 ;klp8 nq7 kz50*iugc+qkb52di ,ezzrstar at 4.3 b uq k 852p7zez0+l*;iriqd5z,kgkc n ly?

  The apparent brightnessa1qjl. n.uu6j 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 abdu+ v )1il/kj7fw mz(ge of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mlyvz i+ kw/m7lfj1bd) u(, estimate the age of the universe, in years.

  If a galaxy is moving away from 5ebbmf;s2 f0/ bv pd0vus at 1.0% of the speed of light, how far away is it from ub bdev2 ;m0/v sb5f0pfs?

  Estimate the speed of a qhryg d. 96u*u ga9t6) yea c.t(necu9galaxy that is 10 billion light-years away.

  Estimate the observed wavelength m)oa0k9t*)g zvx urg3for the 656 nm line in the spectrum of a star which i*r3m) au)0 ok9ggxzt vs 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe warjyax op .j5mkc*.lrb*b *h9:s about 1013 K. What *j:xrac r hobb5 jy9pl.k*m*. energy (in eV) does this correspond to?