The appearance of the great range of brightness among stars is ducm 9cd kvq:)5ne to

  The absolute luminosity for most s/nz s tan60au+sx; jnaxj.+m -tars depends on the

  Four different main-sequence stars are colored blue, orange, red, and yellow. ks91h.jtu , owWhat is their rank from coolesso1ku9 th.jw, t to hottest?

  A Hertzsprung-Russell diagram shows stars on a i6vradk8a g 0on s(h,;plot of

  A white dwarf star with a mass equiwtovg,:(47ro . 7c2 t :5pgqivp xpsral to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star wi7o .zkpz ewf1*ll collapse into a white dw7ze1 oz p.wk*farf) is, if the mass of our Sun is M, about

  Supernovas are thouga+2c p:lwvaw,ji8g 5hht to always result in

  Black holes

  Pulsars are rapidly spinnijt0yo/:rxxw(wl y8 +ong

State Einstein's principle of uvs ok3r,*4s ;pb2o xmrf: u;uequivalence.

  The Schwarzschild radius of67juajim +.hc* 9utll a black hole is that radial distance from the center of a sphere within which not even 7jjm.+u6i ca 9hul*t llight 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 rs )i 7wi en/fnlnp;/ 94wmy2ou*0amcin the visible, and the sourcw mi *74 ysnr/neo;u0)pmnla9i /2fwce is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature ohq6 9yas1:4ehdbq * juf about

  The Sun has apparent brightness atcucxyjnw qj1:4:.c:yxb ede.y2o ,8b 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 equ n8 )jv2af029qnlskume;nmv( al 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 radius of u:t9unlz e( 5 f1 1yqwla+f4mc$1.5 \times 10^{8} \; km$. 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 mem q8xzyex559 n4 mou)sf. 5d/stoykr8 an 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)cii8n pk 2dt5 Proxima Centauri, which is Earth's nearest star at 4.3 ly? cnik25 tpi8d)

  The apparent brightness of a / x3jfh)pr. *lsx+oir 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 universfhy k*mc.7z v3aty6v 4e is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the univt 4hzm .v yyc*vka736ferse, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far away ip ;utv+w;sl2 js it;pvswl;+ u tj2 from us?

  Estimate the speed of a galaxy that is 10 billion light-years fc6f wz *ck.8- ufe8.nvlnzl( away.

  Estimate the observed wavelength for the 656 nm line in the spectx6uo9 . dd*rhkb1l8 o c7;oujgrum of a star which is c o dlko ox.b9uu h;*j71g8dr6100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of rx /63 7t m3fyrxqy*ycthe universe was about 1013 K. What energy (in ef 7rxyxrtq*yy3 6/m 3cV) does this correspond to?