The appearance of the great range oj.hgj8;r4 4w yzapm:gf brightness among stars is due to

  The absolute luminosity fomt9x3 z 8s,lhvr most stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yellow. ci.xruyo:gzjg9 )4;l2vs. ejWhat is g9ej g;z. .y2ox: )vjslru c4itheir rank from coolest to hottest?

  A Hertzsprung-Russelzgd lru-mr9zq5 q5yf:a;i5b(l diagram shows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is ab,wtpz ;a2r( r hhy-2efyn(-iq out the size of

  The Chandrasekhar lidlzwa:lox ,v qfu5a.2+p4sr) mit of stellar mass (below which a star will collapse into a white dwar u4 .sa5la+z, xo2:pdvlr)wq ff) is, if the mass of our Sun is M, about

  Supernovas are thought to alwad*1dovx ;b) / dtoquxd* 8rlr9ys result in

  Black holes

  Pulsars are rapidly spinninb+j 1hsnxs 5p)g

State Einstein's principle of equ nuqkg97jy/,y /mhsk; ivalence.

  The Schwarzschild radius of a black hole bj,m.i 1r3lo uis that radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published ho3mr,u 1jl. ibis 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 vis o93 8,wr1 /usiynydxkible, and the source is moving away from us, the color of the light appears to us to be shifted towaury syxoik wdn398/1, rd the

  The cosmic background radiation corresponds to a tembojxyr l3xs u4h:v7ph1w wzm(b 81j pd4*)4p kperature of about

  The Sun has apparent brightness at Earth (qos;hk o.,6 vy$1.5 \times 10^{8} \; km$ 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 ttz0( v:js,m hahat 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 ayp(v:ie 0b:advi7 e6m 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 radius ox8r p7zoj q,c)g pxur*:zt68p f $1.5 \times 10^{8} \; km$. 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 Prw1bre3mkbxk)6hy:odn+ l)q 8ps s0 4aoxima Centauri, which is Earth's nearest star at 4.3 lyla8 qps6)yxhsmkk41:b d0enb+3) row ?

  The apparent brightness of rxyg0mrp :*o mf69 ,qo j/aoo,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 Hf(,3fptahw*:yn3- vlb c cw(rvl. k5 p is the Hubble constant. Taking H = 20 kv*a(: rfk , tf5whycwvlcbp(3l p. n3-m/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, how sn rb; r6r+i;afar away is it from us;;an+b 6rrirs?

  Estimate the speed of hx ei8iyeh52i:fb /u5 a galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for tt 6bimfk 4w/ 0nq8wwa+i3mv 5uhe 656 nm line in the spectrum of a star which is w b/qnk5u8i 63mmw0aifv +t4w100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was .3 bn:v4e,gl efp/ohj about 1013 K. What energy (in eV) does 4l/ho gj nfbpe3,e.:vthis correspond to?