The appearance of the great range of brightness amongj wg ip (grel*9hz(:t1 stars is due to

  The absolute luminosity for most s-dr bkvobguylet- gte 0p;)n*6ll -:- tars depends on the

  Four different main-sequenw 9mqjbcm 4)fpb r3)f;ce stars are colored blue, orange, red, and yellow. What is their rank from coolestj f4qm ) 3;bpb9mcfw)r to hottest?

  A Hertzsprung-Russell diagram shows stars on b0j cai0c*( jpa plot of

  A white dwarf star with a mass equal to that of thib1g nzn,rb(d-x q,p/k .py; ve Sun is about the size of

  The Chandrasekhar liucxwj k9z4ut px9i 9a-79;gb mmit of stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun ug4wpt7-9ck9;zu9mx i b 9xaj is M, about

  Supernovas are thoughonudb/ cdhbh.8: ii,/t to always result in

  Black holes

  Pulsars are rapidly gn: /esi xic.0spinning

State Einstein's principle of equivale6ueh 6mwm +t:ldu+ob- nce.

  The Schwarzschild radius of a bla3nbn5hc391alze g *4s tv7su eck hole is that radial distance from the center of a sphere within which not even light can esc h3 5b 14csev7nale93z gs*ntuape. 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 par;4ojq k 77ufvlticular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be shifted tkjlf47;o7 uv qoward the

  The cosmic background radiation corresponds to a tempegx)oqgi1t1j f1 -b4s mrature of about

  The Sun has apparent brightness at Eartsfl*(6 ehg7 vnh ($1.5 \times 10^{8} \; km$ 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 Sunc ,(u tmps;ao, ($1.5 \times 10^{8} \; km$ 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 meafbq am( :2va:yn 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 kp3 )gg/pgj9na mean 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 + c( y(wmr*5wj3ofpbaCentauri, which is Earth's nearest star at 4.* bam3fwp ((5jrw co+y3 ly?

  The apparent brightnesswxh oqjn; 3qnfw vk4d).z8em6*1uix, 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 th/p,9n ;cx v sqxg4axydve2*d 3e approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estiqv x pv/ca;dny9xxd243*s, egmate the age of the universe, in years.

  If a galaxy is moving away from us ueim(ro84l 1 tat 1.0% of the speed of light, how far away is it4 io1elrtum (8 from us?

  Estimate the speed of-pkrjq /*/b5 ygy yti/ an4j*zx x0xw: a galaxy that is 10 billion light-years away.

  Estimate the observed wt00z c: /bh82qebp arux5q5qdavelength for the 656 nm line in the spectrum of a star wh0/bqudeqr pqa c055bh8 z2xt:ich is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature ofwsi2 r(prt et:t;1-tcc:s,kro)npldd7ci 7 8 the universe was about 1013 K. What energy dps -sk7wi8e:7r;tl,o1pric:(ct ttc d n)r2(in eV) does this correspond to?