The appearance of the great range of brightness among stars if a1kl2k9k8yc s due to

  The absolute luminosity for most stars z e33 g2 u,rud*l gtk(bj7m4sqdepends on the

  Four different main-sequence s bb5xnh61,jq (3eu v-w6gjdbstars are colored blue, orange, red, and yellow. What is their d wu 3(bqx6ejbvhg-,1nsj b 56rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot ofj5mv zm vi2vb dd1if4(e5+z0g

  A white dwarf star w qu.xmd u63e. wcf3b3hith a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will 7gubkmzokh;zi-8,oas xg l 7x/*ns.(collapse into a white dwarf) is, if the mass of our Sun is M, a*lx gz 8kzokbox(;/ assgm7ih ,u.7-nbout

  Supernovas are thoughtuky4o6ev,8m mybqm8 7 to always result in

  Black holes

  Pulsars are rapidly 4b10-fg*2o cz9wtl xknc ul -sspinning

State Einstein's princif9x(, 2ex4g fc )jjny2d6fdb cple of equivalence.

  The Schwarzschild radius of rho8 jej yn++fexw 5 dtc488f1a 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 +dj5tenx8 rye jhw +c8 4f8o1fSchwarzschild 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 particulnwphw00w8b;l0c nb+uiau:b3b 2h 4 nvar wavelength in the visible, and the source is moving away from us, t;c2:wbi0hb0v +b03 nu4un a 8pw lbhwnhe color of the light appears to us to be shifted toward the

  The cosmic backgroundx3)iyd 51b uza radiation corresponds to a temperature of about

  The Sun has apparent brightneu+o(e;.sd uh nss at 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 that of th zn 3p y 7e6gdn(-mgma6(sxyr1e 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 alv ,.o-2,nc-iecw uwk 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 km?

  The Earth's orbit ha585;eshspvlcb 8 5jyys 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 Earw/wv 5qx 4m)ssth's nearest star at 4ws v5/ wsm)qx4.3 ly?

  The apparent brightness of 1q tj*mxu j6qeg.w a4 r*y1ix*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, where H is -pt(w d-9moq bw az0-ia+0lxt90y7 usnd3cpr the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the univerp or-t09 awi03 ym(7d-a-unw cpq0x+bszt9ldse, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far acy vk6z5 (gjm.t p1twl; cr8i)cd,)caway is it fromk1, yi )jml)zwp8.ccrv dc(a;t 5g6t c us?

  Estimate the speed of a galaxy that is 10 billion light-yeaw.8 zm 5bez4izrs away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a star q2sp3n 5ue-1g )mfjwswhich is 100 million lighs5jpw1g) -fnm3 usqe2 t-years from us.

  About 1 ms after the Big Bang, the temperature of the universet4//nwl :axzv was about 1013 K. What energy (in eV) does this //xaz :nlv w4tcorrespond to?