The appearance of the great range of brightnes27 c+mgk e*ge t yu .s)sxlrdg9:fsv5*s among stars is due to

  The absolute luminosity for most cgw)d( q1km6hstars depends on the

  Four different main-se,/h)p, :yr-sm dpki2incbis: quence stars are colored blue, orange, red, and yellow. What is their rank from coolest to hottp: /-2c)di sys,n:bmri ip hk,est?

  A Hertzsprung-Russell diagms)hc+t :/,6mhn s ugaa2(k- 9cs ufchram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is +zvl3k g. qy(sds+o/uabout the size of

  The Chandrasekhar limit of stella:smx nqb2; l)qt*pm9 uj um2rv0e-0fkr mass (below which a star will collapse into a whifkm: jmequqr)-p;lsnxu 2b9 0 *v 02tmte dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to always re;zj:jr0aa;zede*9 j i sult in

  Black holes

  Pulsars are rapidly spi.wr 8oh6tqu l9nning

State Einstein's principle of equgz,: h -za1*bzywu00nylpu) 5zid b qwi:k 79zivalence.

  The Schwarzschild radius of a black hole is that radial distance from th 5njg,pt, ;y5veva2pye center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein p,ep5yp ;,v5ya2njtvg ublished 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 wavelength h7o 6s4hmyq.u in the visible, and the source is moving away from us, the color of the light appears to us to be shift76 q .uhshm4yoed toward the

  The cosmic background radiation corresponds to a temperature 4 deudt89mzl:of about

  The Sun has apparent brightness at + 6ixsj+ex-buo m u0d5Earth ($1.5 \times 10^{8} \; km$ 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 the Su ws..dag188gs 7bii4p wbug1o n ($1.5 \times 10^{8} \; km$ 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 oyu t, b2ac/du*f $1.5 \times 10^{8} \; km$. 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 hasn uc(oxh (.fb9 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 nearesir r/sn:u x9m;t star a;n irmrx:9/ sut 4.3 ly?

  The apparent brightnessqbq9 ia/24kh 7i qtg1q 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 appi)u pk)lz9g ysdd)fi , 89)nwiroximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in k9 d gpl )n)f),i) 9uiiw8sdyzyears.

  If a galaxy is moving away from us at 1.0% ofoo9kb +f.1 o(t3goeketp4c1o 0 cd0muk-f,x b the speed of light, how far away is it fob01pc oto+fu .3co9gt d4bf xmke0,k( oe-1 krom us?

  Estimate the speed of a galaxy that is 10 billion hfbz4h+kl3+z.7x 4d z;splr p light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrumr3fy0pq/h* 8 /cdeums of a star which is 100 mis em3*/ duq pr0f8y/hcllion light-years from us.

  About 1 ms after the Big Bang, the temperur 7td *;iy/brature of the universe was about 1013 K. What energy ;b7 t*ryu/idr (in eV) does this correspond to?