The appearance of the great range of m n tfv uk1v2:c497jldbrightness among stars is due to

  The absolute luminosity for mkew5.q eawk+f;wfydsu367f7 w5 ) undost stars depends on the

  Four different main-sequencegaatqax8la 15pnn 9; ) stars are colored blue, orange, red, and yellow. What is their rank from coolest to h5aa ;nt a 9g8nqa1)lpxottest?

  A Hertzsprung-Russell diagram shows stars on a plo/zp1ab0x npikb p 9s-n:-yzhy-q 3fy 9t of

  A white dwarf star withq l)7s6ye 5yqkylsa6: a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below fm tkku m:ai9a,k c9nmk639y) which a star will collapse into a white dwarf) is, if the m kmmktn k9mfcuiy96, a)93ka :ass of our Sun is M, about

  Supernovas are thought to alwaysy1 )c/efy*t fn+rdry- result in

  Black holes

  Pulsars are rapidly spinkf2l0rahc72(nga- bulb;r sy dw 8i3*ning

State Einstein's prin-g 2sfqj3kgo 8q6:q chciple of equivalence.

  The Schwarzschild radius of a black hole is that radhyjm ud7:3xy8 e0( fcvial distance from the center of a sphere within which not even light can escape. It was first discovered mayv u0(d 8x:f j3ymhce7thematically by Schwarzschild 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 waveleng8(g pk9ddh w1:)x ojj vir+9hlth in the visible, and the source is moving away from us, the color of the light apph) 9l kdovdx8hgi+p( 1j9wr:jears to us to be shifted toward the

  The cosmic background radiation corresponds to a temp,jsetugt9fbm b/ 4iy4*lg4n2 erature of about

  The Sun has apparent brightness ayt ( u2s08mjfvvmc44/da p(ry 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 luminosity equal to f46qr-4hax7f j m17ko* k7elg o)nfeathat 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 mem t gutl i8y9;84d.ezzan 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 km?

  The Earth's orbit has a mean radio zi)wdbbj,-x3ig5 6cus 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 isozgji ,)9w +ic Earth's nearest star a)zj9 ,iw+ oicgt 4.3 ly?

  The apparent brightness of a st u) +qsn3m +esfxz/on0ar 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 approximay /1z t0mzp;jhte age of the universe is 1/H, where H is the Hubble constant. Takin0zhy1 t/ ;zjpmg 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 spee(hzvu1 t (3fpld of light, how far away is v((flpu3zt 1hit from us?

  Estimate the speed of a galaw /-nem 0g reobfl2x,5sz+o m2xy that is 10 billion light-years away.

  Estimate the observed-cwf1i6ju7lm 3s 7 kfq)j;aip wavelength for the 656 nm line in the spectrum of a star whkja; w cf6j3isq )li7p17fu -mich is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universeldp u.xl 1v9hbk4.z31fv/vxm was about 1013 K. What energy (.z1x pv. bku/14 dv9xvm3lhlfin eV) does this correspond to?