The appearance of the great range of brightness among3/ro 2ngai+hd stars is due to

  The absolute luminosity for most cdt5.prko:3 c stars depends on the

  Four different main-sequence stars are colored blue, orange, red,:hi 6g9o sh+8 gc1jgr c19mrmg and yellow. What is their rank frgc1r8 mgjgs1r +mh 9gi 9o6ch:om coolest to hottest?

  A Hertzsprung-Russell dy5h sda64,qihiagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sunp2djg-1 8+vicx1 :urctaf- jr is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse into atl8 goo3k. 3 y;9buqjt,,wd po white dwarf) is, if t; 8 pt3qwoo3bkgut, od 9l,jy.he mass of our Sun is M, about

  Supernovas are thought to always resuuq;j f.m gp 6t/j.b7pblt in

  Black holes

  Pulsars are rapidly sp:j0xv)xkqqo a 91+mqainning

State Einstein's principle of equivalen3pje9div4*u:s jey g,p/(zjx vh-m-tce.

  The Schwarzschild radius of a black hole is that radial dizyg04. ijru )a+d.oq0 i9mrofstance 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 generd) y.i0m oua4+rqjo0i.r 9 fgzal 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 particul6g1 s08 hda2ruya5zlk ar wavelength in the visible, and the sourcgl rs065 2z8kh uaayd1e is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperaturk m0kol1 mxl6ln+)9r le of about

  The Sun has apparent brightness at Eartca 5zf )7t jv+gu35vijh ($1.5 \times 10^{8} \; km$ 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 tha a,9rz /kt)svihy.u s *1j*jsct 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 r ocjpt/+t9*wp,dhz -u 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 hakkuq: h vr udtqer1 -(+i(70drs 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which is Earth's nearest st7 p*; avsplkr ol:1d6z2-k jthar avl hzk-k21* p: rjp6os;l 7datt 4.3 ly?

  The apparent brightness of a star od,gps uxe+/u+zf 0n) 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, where H iskiu /sbmdqf 8)w5p*5 x the Hubble cofus pb*8)xk/qi 5md5wnstant. 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 light, how wko/k7co-w+ y6ee,q bfar away is it frome-be /co k7o,yk+w qw6 us?

  Estimate the speed of a ga.s-0g y/ukyw7q4pp0d(xwuw; k r +rfxlaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of 20kvt cp 3xtjy.8 kj9ja star which is 100 3jp9vkxky02tj8 .tcjmillion light-years from us.

  About 1 ms after the Big Bang, the temperature of the cxnd ;6 ,p-.t 2oijykyuniverse was about 1013 K. What energy (in eV) does this correspondyd,;k2y oc -x.p int6j to?