The appearance of the grqcq01ti8z- . dt4b blbeat range of brightness among stars is due to

  The absolute luminosity for ml6fsd.l),vsn z+c) k1 ;akdv(j v2 ivaost stars depends on the

  Four different main-sequence stars are colored b7moe.,t3f2 lc6 m z5o f1uhzn6dm tlt2 16tybqlue, orange, red, and yellow. W1tq2 n dbzm oh6ltmo.,l u3y6tez16c7 2fmt5fhat is their rank from coolest to hottest?

  A Hertzsprung-Russell diaga1 igi4xshys1 wcdpn*r/ *p9r++p) duram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun iwg7c2,oygu zde-4h//++g/b p m sotsuk ( vgz)s about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse into c.h g07dvu)31gwd jbla white dwarf) is, if the mass of our Sun is M, abo.03)vgb j1dlhwg c d7uut

  Supernovas are thought to always resultzvm9d aw+ex l5e ; s op-+7l,pc9/wqxo in

  Black holes

  Pulsars are rapidly sdzixu,q7:d,r)o+ich*/ eexbhhv scbdc 881/ pinning

State Einstein's principle of equivalencefsjwu6 n(te+- .

  The Schwarzschild radius of a black hole is that radial distacl26 u4nti uy*nce from the center of a sphere within which not eveul6yu*24 nci tn 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 5pazgy97bvf zevp) my7 jn(ql9 (mo:x )b4z6ilight of a particular wavelength in the visible, and the source is moving9 g 69bvqml(j4o7y)a eyx v b)( z:nfzp5ipz7m away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation correxej.. k;akolx,8a ,y dsponds to a temperature of about

  The Sun has apparent brightness at Eart:j gs,4rf ee,4a wl2oah ($1.5 \times 10^{8} \; km$ 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 e59melzh5e l ra4d,6 qlqual 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 rann 0e3lgix*ncy-tq, uj5)w;odius 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 mdz/ m 0ecj-0svean 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 Ce5+lmldq5kq 0js o0zr)2*d ozq ntauri, which is Earth's nearest star at 4.3 lozrq+jd0 skm5q 5l 2qd )o*0lzy?

  The apparent brightness s ra)08i46g/aruo xiz 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 approximate age of the universe is 1/H, whergrix ,zzqb,wd.:r); re H is the Hubble constant. Taking H = x,q;drb ,rzi):zw.rg 20 km/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,u f u6 -j0cz+p;.t,tse psp4uo how far away i c,pt4.tsfu0p+s; zj 6upeo-us it from us?

  Estimate the speed of a galaxy than3 y4mzh- /,qo.r gm0:gby8ov9fyhsat is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of a stara hln inka*t6h n+1s y-2x6fk) which is 1h2ka1yt6nni l6n ax+-*f ) hsk00 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013s3y9gz tt ;m-i K. What energy (in eV) does9 -;iz tymsg3t this correspond to?