The appearance of the great range of brightness among uq wsu .,whd.uu0 0ug7stars is due to

  The absolute luminosity for mos7c a-za4ng/k.b)r pjgt stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yeln.0 zt pxx+-(qtzn m7iua /z:blow. What is their rank from cooleszax+0niz7un bt.:- p/t xz(mq t to hottest?

  A Hertzsprung-Russell diagrrxw8k :v0 hnaizkgbc qcw/bm, e3z93: jc.t(- am shows stars on a plot of

  A white dwarf star with a mass equal to that 9j8aemrxcah*d 3 /eq,bs q;gqv:hy43 of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse intaer36cmz3 u-f o a white dwarf) is, if the mass of our Sun is M, af-mre336u azc bout

  Supernovas are thoughp c7o+x:96ke vhtli. xt to always result in

  Black holes

  Pulsars are rapidly sp-;-wl3ne q w 7,l+cvhleflvg -inning

State Einstein's principle of equivu8pp 3-)+7neosbn syn alence.

  The Schwarzschild radius of a black hole is that radial distance frombp51r8z5f ap o the center of a sphere within which not even light can escape. It was first discovered mathe 1 bpp5oar85fzmatically 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 wavelength in tho d-cn(*ezoyw+kmtd.fs if3 g3t f4,9e visible, and the source is moving away from us, the color of the light appears to us to be shifndz d,3t9 soekf yicft(3m .w-4gf+*oted toward the

  The cosmic background rng./ v( t0vcigadiation corresponds to a temperature of about

  The Sun has apparent bri7fz +i1gguwz *ghtness 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 3feh f .x0hgwk2r+hfo g 2f22gof 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 hahd :i4g 2 znh i,rksnj fj,-a)h dx7zm/0g*:oxs 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 km?

  The Earth's orbit has a mean ri zruhj)o,hv3w., .z* wqddew)u4:z a 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which is ksajuf83bw)fg7m ck3za9++ tEarth's nearest star atf3m8 u twj+ckksbafg7a3z+)9 4.3 ly?

  The apparent brightness of a star vicn1) stvr 3703 pj)sufd2jois $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of thvs srk. :pc:kd0 3fgf6e universe is 1/H, where H is the Hubble constant. Taking H = 20 r::pc3sf skgv df.6k0km/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, ho o6,;f i 5wtje8 ls(ro;2nmb7h+o scgpw far away i2r(5cb7t+i6;l p o; ,ogsshoem8n w fjs it from us?

  Estimate the speed of a galaxy thatt- j/n0abgvv47e gmc8 x.l:q0k0 qlml is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a 97* cbw3bjulk star which is 100 millionu 3cb*kjb7 9lw light-years from us.

  About 1 ms after the Big Bang, the tempem vks1 j7bua/6uk.:lhrature of the universe was about 1013 K. What energy (in s m7/kl.khau61bu j: veV) does this correspond to?