The appearance of the great range of brightnes6-/f6wbc*o afisuz0 fm .k c/os among stars is due to

  The absolute luminosity for most sti9b:n+wz0bblbl 2 +oears depends on the

  Four different main-sequence stars are colored blue, orange, red, and yes2p;xpc*r12-v(j fdlw;n vz d llow. What is their rank from coolest to hottcf2s1d jzwpr; (;lvp2dx *-nvest?

  A Hertzsprung-Russell diagrwkch76 yuq 24*c,vg*noer-iitf *, w oam shows stars on a plot of

  A white dwarf star with a mass eqpn,8n-v0 h32c q:t bh-uuy xjbual to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse into 2ziw vi:7 +eg,u1 tclba white dwarf) is, if t1uczw +i:vig,e2t b7lhe mass of our Sun is M, about

  Supernovas are thought t :xlnh 0n*:krjo always result in

  Black holes

  Pulsars are rapidly spik j9g2 ;3t1+ixc essazm5w c19vlm.zs nning

State Einstein's principle of equivaleneltqcl vl5 +hod;idf,u j(d/4ls;7w5 ce.

  The Schwarzschild radius of a black hole is that radial distance from the cen413umnke td 1l necz8j 682hkoter of a sphere within which not even 1lto ude3he4 21 z6mj8nkkn8clight 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 wa9w z** 9znlstvvelength in the visible, and the source is moving away from us, the color of the light appears9zv*lt 9s*nwz to us to be shifted toward the

  The cosmic background gpr- qh-mu02yradiation corresponds to a temperature of about

  The Sun has apparentc d4;/z99z2wt.pnaci hd q 9ac 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 um.vk +s*)zg i3vl1 eethat 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 mean0 (smc mo77iqshmuq 15 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 mean radius ofq jw -xzhd ds-* ;c2be0u-vfv; $1.5 \times 10^{8} \; km$. 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, wf .qiy p2c omahpo)+(7 e*p*bbhich is Earth's nearest star atoqmbbp)ih **oya (c7f e p2p.+ 4.3 ly?

  The apparent brightness b4ihch/uaz4.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 universe is 1/H, wher3qb8f7w3t fk pe H is the Hubble constant. Taking H = 20 km/s/Mly, estimate kf t3wqbp83f7the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of lighic7k06 yfn4 bpt, how far away is it ncb4yfpk7 0 i6from us?

  Estimate the speed of a galaxy that is 10 billion light-years away;fqm ( z p6.r7mi6ilza.

  Estimate the observed wavelength for the 656 nm line in the s0k -0i ftmvm-2mw fhoknbuv 4,28h y3mpectrum of a star which is 100 million light-years from0ub 42t3m8,o0-v2nkmf vmh-hkm wif y us.

  About 1 ms after the Big Bang, the temperature of the univ0c / +3xwmya01ro-t stnb fgp1erse was about 1013 K. What energy (in eV) does this corrcp0t/ f0 yswbonx1m-1g+tra3espond to?