The appearance of the great raz/(gxoi/q;i gvq2frgp68p/ rnge of brightness among stars is due to

  The absolute luminosity for most sta shqikl8) b,v*nw 1z*0bpoad(rs depends on the

  Four different main-sequence stars are colored blue, orangeup;s tmf1*:*ezp u wj7, red, and yellow. What is theirfw p71j*e;usz:m*p u t rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a w:dv;8u66 pzsp yo) wwplot of

  A white dwarf star with a mass equal to that of the Sun is abz vy3;m6n t3unout the size of

  The Chandrasekhar limit of stellar mass (belob :l/ 6c2czf2uuff(m5lpu 7cpw which a star will collapse into a white dwarf) is, if the mass of our Sun is 2 :lf(m6puccpu 2b/ fl7fc 5uzM, about

  Supernovas are thought to always result qj:j of,elyap4,qde : 2+cpq6 in

  Black holes

  Pulsars are rapidly spinningi,ld 3jw ;ld,i

State Einstein's principle of y+rnd u9jzgqgl6o1 itg(*. m2 equivalence.

  The Schwarzschild radius of a black hole is that ra*+di6fux)ayt5r y9 dt dial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein published his general relativity rtf+*y dai5t)du 9yx6 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 in t *ix2cdo06qj ui7u:k jhe visible, and thic*dx7062jj quiu: koe source 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 o9 vnbv(5ced2td91vzyu2bi; hf about

  The Sun has apparent brightness at Eaw um9 0n).t99csku;zt8 lfpkd rth ($1.5 \times 10^{8} \; km$ 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 that of the Sun ns ehyi v8l,:d *;qqv;($1.5 \times 10^{8} \; km$ 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 0bh(o-q;ue oo 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 rd t k5gcsb-bogjz) 05.adius 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 i3yz-l/kyx h x ek5(zj;s Earth's nearest star a;(xe z/hl3-jy5yk kx zt 4.3 ly?

  The apparent brightness of a star is r,: cqq1 -e 8yb) ttzabha8(uu$1.0 \times 10^{-12} \; W/m^{2}$ 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, where H up 2hkr 8per4j)+y6+dj.tkads ; : qoiis the Hubble constant. Takindh.dup:+rko +ptajj 6r2q4);i kye8sg H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving a 9/8u,o l plhj3iur)cxway from us at 1.0% of the speed of light, how far away is 8u9l/li)u3 j, ohc xrpit from us?

  Estimate the speed of a galax 3 p1c;q9ghsk*suhbrk4ly 7l e(p3bf)y that is 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum 8kei0d+:ye rm of a star wir mke8y+:0e dhich is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperatur,.hphqm 50api e of the universe was about 1013 K. Whm pq .p0hih5,aat energy (in eV) does this correspond to?