The appearance of the great ry elico7 f1ap..vd +a0des1a 9ange of brightness among stars is due to

  The absolute luminosity for most stars depends on tz w*5q,nx 0zjmhe

  Four different main-sequence x t 3wmm8bam45hd,car6o4,dp stars are colored blue, orange, red, and yellow. Whd6,p5ct o hb, 34 w84mmamrdaxat is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plox2fqoc -0a *ihu v0qz8t of

  A white dwarf star with a mass equal to that u/js:rho eo gd(5pzoynnh *86pb06+ d of the Sun is about the size of

  The Chandrasekhar limit of stel7vhf(5q zi:hn lar mass (below which a star will collapse into a whi5n viqf(7hz :hte dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought t-32 ,a ;bfs hu7xztbkvp g48hfo always result in

  Black holes

  Pulsars are rapidly spinni 0/qulgt)2ea wpm5j skc7 6p/zng

State Einstein's principle of equivalnehk)1 w;tt**j smh 0lence.

  The Schwarzschild radius of a black hole is that radial distab.25 tg0rp 4dw.bvzw gnce from the center of a sphere within which not even light can escape. It was first discovered mathemati05ww.. gb v4pgb2zdtrcally 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, an -;dikvxklge3c r sbz-:(v x/0d the source is moving away from us, the color of the light appears to u szg-; vxvc0ibrk:x3 (e- /lkds to be shifted toward the

  The cosmic background radiation correspopp+zf.a3d+ b-imf.zy q/)dq j*pr o +jnds to a temperature of about

  The Sun has apparent:t -( y)w. dkrpduwb4a brightness 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 of the /fpfelo2vi1,r -it*2wi/t6 e gmug.fSun ($1.5 \times 10^{8} \; km$ 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 4rvahrux,- 10b2dphzir j 6w 8mean 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 aem :0go) juzxcnsr,mf)3l.2i 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 ford6 bnk+qkm :f g9l6(i*o pci(y Proxima Centauri, which is Earth's nearest star at nkbkpcqo 6 gf m96(:(di *+liy4.3 ly?

  The apparent brightness of a stad mr7hz7 a89zbr 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 thatbd4y+xi*uj*na : hd : mr9-hhz the approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/hud jybn -*9x*+4izhmr d:h :as/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 far a ejux9 z)w*rb./wh1qio dg,6nway ijbd1rq9o/)w.un gxe z i6h,w*s it from us?

  Estimate the speed of aw;x dut9/6m aloy) qv; galaxy that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spech, n ;81woijo5a0jcobtrum of a star which is 100 million light-year 5o81 h c;,jjanwoo0bis from us.

  About 1 ms after the Big Banpghesu)e-awak4 / 6 d0g, the temperature of the universe was about 1013 K. What ened0wpshae46ka-g) u e/rgy (in eV) does this correspond to?