The appearance of the 1d (k;05 d9awih9q;ho ynhe wwgreat range of brightness among stars is due to

  The absolute luminosityen37m4;af2yydwf n ,4zz oz2n2d* 2 gk3iqmw y for most stars depends on the

  Four different main-sequence stars are colored blue, oah:8ytcbzw(3bz t1 * do d6uw(x* luh2range, red, and yellow. What is their rank from1zt l b *ywddoxwc(*6uhh38abzut2:( coolest to hottest?

  A Hertzsprung-Russell diagr4sk- k3+ aa2bht6gc 0ykyf4k xam shows stars on a plot of

  A white dwarf star withuk7 z ua9u6:o15qfeo0e y+y sy a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below whif)gfjhg + x:4kxm-*iwch a star will collapse into a*h4f +wk gj mgfixx):- white dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to alms, 8 ,c kmm.q0kgmf0vways result in

  Black holes

  Pulsars are rapidly spinningti6(aqfqu uug6 h1/o .*8nzc. ,-fhdd,w hisz

State Einstein's principle of equivalencetq:5l:t*d5+ lx k vjcf8m8y ma.

  The Schwarzschild radius ov w+v8j*ltv-.pt eutl ;i, k:of a 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 published his general relativity theory. It can be calculated from a sto+ju:it-v wt;l l,p.k 8tvev* ar'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 ligph 4sqsn0d+x ;ht of a particular wavelength in the visible, and the source is moving away from us, the color+nxq s;d s4ph0 of the light appears to us to be shifted toward the

  The cosmic background99prdrm 6 6+vsxcoz0v radiation corresponds to a temperature of about

  The Sun has apparent brightness at Earl2 9zwve8 ffd+pti:(xth ($1.5 \times 10^{8} \; km$ 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 th-i5-clb )ad ciat 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 a* j)-iu1sauxn ,;gy rradius 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 radius hs 9 q+ig6f4e*zkch40l, :fi8uswqx v 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 neare /ba5o nmha*zi;sz3b-*lzu+q st star at 53ab *z ;nq+is*-olbzahu /mz4.3 ly?

  The apparent brightnermv.ti +hv: zf(ukro:m0,xwk8cz: c,ss 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, gy /0yx/;4 n8b5ew ltsr.zm inwhere H is the Hubble constant. Taking H = n8y/z b.4r0g;5y st/eliwmxn 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from usyq:4v: ,eb4gn r4b1od2zarrd at 1.0% of the speed of light, how far away is it from us?v1gbdr4e,: r:bq 4yo2nazd 4r

  Estimate the speed of a gakh5s* .bmql*npu et5g6jg0k.s p,m w+laxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of *)p3f p8wti jqa star which is 100 million light-yea *fjpi)pw8q 3trs from us.

  About 1 ms after the Big Bang, the temperature of the univefug gv0m*b e*,(p* cdgrse was about 1013 K. What energy (in eV) bg,mcfe*(v0d *p ug*gdoes this correspond to?