The appearance of the great range of o,5wk laba/ hd:sy8)- iggr6 ubrightness among stars is due to

  The absolute luminosity for moss4l : +*5y bw6rugqqeqt stars depends on the

  Four different main-sequence stars are colored blueg5unei xa5; 9g* p*xtt, orange, red, and yellow. What is their rank ; xiu n9*pttxg5eg5*a from coolest to hottest?

  A Hertzsprung-Russell diaz3wgjx0 e:k-ap4 px0 x9o*ecpgram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the size o0 g8 lspjm;vvykbhaz 8 .*/)xrf

  The Chandrasekhar limit of ste,qv ko t1ps3dv*z: g+3tvmk*pcp0u d(llar mass (below which a star will collapse into a white dwarf) is, if thkdg*(pto3mp : vt d0 vzkv+ups1c*3q,e mass of our Sun is M, about

  Supernovas are thought to always result0(ix8jvuj08b unrqc (j8 kgqox,x 76f in

  Black holes

  Pulsars are rapidly sy gq i,)4 k b6iff.elmwt8rcys. 7;8cdpinning

State Einstein's principle of s6rq ;gi 39h+xp/pxp xequivalence.

  The Schwarzschild radius of a black ,pt a;ae a :7jn-w9zlxhole is that radial distance from the centera waptljx e-; :97,zna 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 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 the viz5+enmgt)4w ud-;m+z uuu6x c fik*h0sible, and the source is moving away from us, the color of the light appeaxmu n) u4iug chewd0k;mft +-z5uz*6+rs to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of abosg+mt) y 6m/ky,hgaa mpb048put

  The Sun has apparent brigh-.fsx 4 vlrrz9tness 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 i9oce 6+rki, fh )r5f jri,7lcof 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 radius of 6q/*ohh*9oogjt t()kjjs a :l $1.5 \times 10^{8} \; km$. 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 o9i4tndvb8 q,sof)+t af $1.5 \times 10^{8} \; km$. 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 i 5 aupc7cne/fjxt*30kv:au q* s Earth's nearest star at :f /puvkc7*3jaetq n0a x*u5c 4.3 ly?

  The apparent brightness of a starwu/yr h a9m:r7 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 ie i.o:,1ibt5+kj frqb *qpa2z s the Hubble constant. Taking H = 20 km/s/Mly, estimate tfbk1eqq5ir izt*,2 + :bjo p.ahe age of the universe, in years.

  If a galaxy is moving away from u5io4f+ 8a 9sideep8kuq 5o-,amdmu2cs at 1.0% of the speed of light, how far away is +e5 uumado8,fdp8i5s-e92 4aikmq ocit from us?

  Estimate the speed ofw u p*7r.v+ckxxh7bz( a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line rx;atczh) p, +55 vexcin the spectrum of a star which is 100 millhz+c;xv)5xper t ,a5 cion light-years from us.

  About 1 ms after the Big Bang, the temperature yapuc ;fsr*+0gc u/y 3i(,ejz*p.jpf of the universe was about 1013 K. What en+,(ej;fui/p.* yzs g*ra cu3yjp 0cp fergy (in eV) does this correspond to?