The appearance of the great range of brightness among starmjt ; k32.vi av.xp*mhs is due to

  The absolute luminosity for most 2g/3ns0w4dr dtrxr4u stars depends on the

  Four different main-sequencjh*j( (81 6hvopab qqle stars are colored blue, orange, red, and yellow. What is their rank from cq opal(hjqbv (8hj *61oolest to hottest?

  A Hertzsprung-Russell diagram shows s0wtcscqo9 *7 ftars on a plot of

  A white dwarf star with a mass equaftv2 ;0sf(4o0amyish l to that of the Sun is about the size of

  The Chandrasekhar limit of st fntd1jk e40 *i s8f8jbx0jzk(ellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sunej jtkx bji* 0s8k0ffz 1n84(d is M, about

  Supernovas are thought tor.w;- +agyg6 mc,i*x v b+83uqoyrizk always result in

  Black holes

  Pulsars are rapidly spinnins6jyl- i,wn d d(dy*mexi*t7-g

State Einstein's principle /0cvfceudg *9qp;h,w 5rkj6v of equivalence.

  The Schwarzschild radius of a black hole is that radial distance fro x7.xvu8 hkurp0x 0 jj:/ihi.em the center of a sphere within which not evenh:kp.jj8xx ei h /vxri70uu .0 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 visible:48;tv,(qwvsf-4+yij zl ;stjdcfcz, and the source is moving away from us, the color of the light appears to us to be shifted towd(j,;i ffqz+v cs8sc zyjvw:-l4;t4t ard the

  The cosmic background radiation corresponds tmv gxr60m7zi8yla:;qo a temperature of about

  The Sun has apparent brightness at Ews)/si 2w9ltry0q*yz arth ($1.5 \times 10^{8} \; km$ 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 luminositzndia/ rq4pg0ag.1)1 l28tilu x,xmvy equal to that 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 mean 3r 8j+m*ka1u jm*jgl)bklv;u 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 hanc :yh vwuhx342jx7c1b* ebq 6s 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 neares ev4 9u;.zeote.g ndn1kafz65 t star at etn4euv. dnz1;zg f o.6ke5 9a4.3 ly?

  The apparent brightness of a starvsxcs2 1ul k,3 ,leet. 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 Hp1,1vd anu 7fq is the Hubble constant. Taking H = 20 km/vafdpn7, 1q u1s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of lighr3g 8p /g fw bk g7aijqz9:sjx.l.eb6(t, how far away is i:. g(bj6ga r l8ezwg.isfq/7k9jb px3t from us?

  Estimate the speed of a galaxy tha+ r4y zgilm4t7t is 10 billion light-years away.

  Estimate the observed wavelength for the 6mb9pfx(rmtauk66q op*:f t3/ 56 nm line in the spectrum of a star which is 100 million light-years from usp9tr b6x *a/oukmpfq(m6: t3f.

  About 1 ms after the Big Bang, the temperature ofrw7nw0*qcbu u,u+,r u the universe was about 1013 K. What energy u r7*u r,,nwwuuc b0+q(in eV) does this correspond to?