The appearance of the gremj(w7 h6k* 08o/lmv-t-lpqbnuc u 7a nat range of brightness among stars is due to

  The absolute luminosity for most stars depe*uho..linca n c1 :yi qae--g;p46x uvnds on the

  Four different main-sequence starsh 23c jv9)raab are colored blue, orange, red, and yellow. What is their rank from coolest to ho)ba jv 2car9h3ttest?

  A Hertzsprung-Russell diagram shows stars on,i1 bqfc*cw-- pr4 yyr a plot of

  A white dwarf star with a mass equa m .*33 q)jttyja0 tzp/j1zzeyl to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will colla,7,nuhuunq 5 mpse into a white dwarf) is, if th75 un,nuh mu,qe mass of our Sun is M, about

  Supernovas are thought to always re bgqy3+/i h,l9kal9 s pgg9vd1sult in

  Black holes

  Pulsars are rapidly spii7/dh *rzwcn;hfz5od4sbm /3nning

State Einstein's principlr(s/3 cu5y rdge of equivalence.

  The Schwarzschild radius of a black hole is t *d/+jnza9 , sr4pm 9oojjlog*hat radial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by p49oom*jsd jn,l9gora*z/ j + 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 particu5cnb86 way pq 4s8;qxzr q)t/nlar wavelength in the visible, and the source is moving away fnt4 5n/sr x 8cqbp8qw;y)a 6zqrom us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds tohkz t9ilqe4. 7ivq2k 5 a temperature of about

  The Sun has apparent brightnw6gf *u *snmf2ess 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 lk. b , tmjyg:dpi/1 x,98lpptt:1cqfpuminosity 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 radius ofdxx-gamdny2 b /ma 4,r-p2 bu4 $1.5 \times 10^{8} \; km$. 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 of1uh4 m6w b77w az:bzii $1.5 \times 10^{8} \; km$. 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, wq/rmdt u*ewvx (rkyyw2;2 e42hich is Earth's nearest star at 4wuw/x;(r2y r yke t4*deqvm2 2.3 ly?

  The apparent brightnesw14sqj5.tw90is 4 yj w.hs oz(y)uav zs of 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 univenjtmb6 -s,6 dow,uby0.1rg mhrse is 1/H, where H is the Hubble cony6wt,mb.n 0 gbd1 soh-,rum6jstant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from g0-c 4rneqm.cus at 1.0% of the speed of light, how far away isgce.-rc n4mq 0 it from us?

  Estimate the speed of a galaxy that is 10 billion light-yearahj 7r37v7i sik .+zlws away.

  Estimate the observed wavelength for the 656 nm line in th. k sydgf7 vyw+bb;;; butr(4he spectrum of a star whichy .(ywdtv;f; sg7kbrh u;b4+b is 100 million light-years from us.

  About 1 ms after the Big Baq6yawxsj v3hf(hby p+ u4/9:6 ydhyt6ng, the temperature of the universe was about 1013 K. What energy (in eV) does this correspond to? bj ywhy9hyhpsdf xa46 u:66(+ /y3tqv