The appearance of the great range of brightness among stars qa0.kjwxai2bz 4j9mv, g5j. w is due to

  The absolute luminosity for most stars depends on thec.umged ,j: y30 6gaci(eawq3

  Four different main-sequwg0xxrh0j 1 ,r;m9n buence stars are colored blue, orange, red, and yellow. Wha9j hun ;0xm1x0w,grrb t is their rank from coolest to hottest?

  A Hertzsprung-Russell1p1v raa s7d)em 8abj1 diagram shows stars on a plot of

  A white dwarf star with a mass equ(zks2nf53nt y v7b*g pal to that of the Sun is about the size of

  The Chandrasekhar limntjgqzq2se coot0 63g) :zb0:it of stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M, abooe0gg6q):nbt 2 sj 0 :cot3zqzut

  Supernovas are thought to always result injvt h-:(hdimo 17fho-

  Black holes

  Pulsars are rapidly spinn jtb-),baf;j9v2 csebing

State Einstein's principle o d)*er2/+ cd+sfhfhiafjmo5v) dt,3w f equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the center mzxqz17p nqqo16, f((ej oin* of a sphere within which not even light can escape. I,*6inoqxznj(p e1qzo q1f7 m(t 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 ay3f 1;fsb)reof a particular wavelength in the visible, and the source is moving away from us, the c1 besf;f3ray) olor of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds toysw2ia8 qk4x9 a temperature of about

  The Sun has apparent brg(fa zbm t9g *)5fxg)vo4l-ttightness 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 tuxdh zo4 b8zxj5 yw; 8h5b ml(rip866to 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 hlw10s)(wu/ fpwyqg3mean 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 mof9u b)k10ki k *mw0qiean 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 nearest star ncrw.+* qp usmfgln,x3xk50 /at /s m,p xcn5lr*+ un.x0gq3fwk4.3 ly?

  The apparent brightness oi .ipme8; ko5 r8s5y84twuk6: jopsaof 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 8q+gst.v zqba*av n 3(lpdi7ds6g2(bage of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universl7n2sia( v.bp (gtqsdqz*3 v8g6a+db e, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far aw;1n7(zq.o s8iw1fal1.jha)i enps pb ay is 7qz.el;i s1sbna p op)8a(ni1h 1wfj. it from us?

  Estimate the speed of a galaxy that is 10 billion light-years a9l3lm 5gk4woz way.

  Estimate the observed wavelength for the 656 nm line in th t gsy318 fu :-y omo/ph4*thtwm:gxn(e spectrum of a star which is 100 million light-years 4 h hmtymw-gtxsf:t3/18:yog uno(*pfrom us.

  About 1 ms after the Big Bang, the temperature of the h gse .j1a9 30(b 3rvkcbyv9xduniverse was about 1013 K. What energy (in eV) does this correspondj.3bv93xdgabh y(190 ek vc rs to?