The appearance of the great range of brightness among skt9zdvx3h-bj,y9 - sk tars is due to

  The absolute luminosity for most stars depends on thct wt*.nj 3m91bs yyh*ms0 p4he

  Four different main-sequence stars are colored blue, orange, retpbyvsu 3k 4 .5duk :a0x9e:qvd, and yellow. What is their rank from coolydue3qsta.b59u 0 p x vk:k:4vest to hottest?

  A Hertzsprung-Russell diagram show8 g7f 0.xsc9zkc0 ash)kcoxom67,jmws stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about the siz8mbs: bxzw5 h)e of

  The Chandrasekhar limit of stellar mag* a9yk0 wicfvfgc eo0xkgn9+;k4e-k- +fqi/ss (below which a star will collapse into a white dwarf) is, if the mass of our Sun4 i+geneo90kg k +/ -c9 fk-kcfx*0wqigv;ayf is M, about

  Supernovas are thought to always wne)vliivo0(w;5gqv4 ra, j7r ntd;7 result in

  Black holes

  Pulsars are rapidly spi 3hn/5hba2)or1 mf k (e6mptsbnning

State Einstein's principle o 0.aicx(y:8pr i1mkasf equivalence.

  The Schwarzschild radius of a black hole is that radial dist ;g guepc,.7f41mo;m+oanouj ance from the center of a sphere within which not even light can escape. It was first discovermgac ;e+ujn7 g4mo1.p, o;ufoed 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 part4g e1ea()z povicular wavelength in the visible, and the source is moving away from us, the color of the ligeezg(v a14)p oht appears to us to be shifted toward the

  The cosmic background radiatkkhd srtn()(m5 zlu5/ion corresponds to a temperature of about

  The Sun has apparent s: xoun(.e8jlbrightness 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 luminosity6k p.; g2r2 niikjnh5a equal 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 rad (.px0u0crzyr/ ce7foius 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 m8b(rx 2 oz;7meb3kmiyq 7ktw9ean 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, whic ;rtqjulob;60 h is Earth's nearest star at 4.3 ly6lur t0 ;;qjob?

  The apparent brightness of a stareioe(l *e4a7u 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 unlt ik-e jkkiy, iw2vu5;x5.d; iverse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, esti-5kux;jie5d ;k,liy iwk 2t v.mate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% oehrd8cf1;m ( ef the speed of light, how far away is it from us r1;d8c(h emfe?

  Estimate the speed of a galaxy that is 10 billion light-yu fiski,m. w.62rpp w97xonx 8ears away.

  Estimate the observed wavelength for the 656 nm line ihzeguan ,0n,k)g7j:h(qz+i xn the spectrum of a star which is 100 million ligh ij: ah(+ k,hz)n0u,e zxg7qgnt-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1heieili2 uu77.z -xx sfv6 cg-g+z27 p013 K. What energy (in eV) doe+xx2ihz7uz-gg fi. 2u6l-ve ip77c ses this correspond to?