The appearance of the great range o*l4 ;v,ll c)k 2cnrjwb00 rlukf brightness among stars is due to

  The absolute luminosityl+ pt rlne-jih0zg 0*7 for most stars depends on the

  Four different main-sequence stars are colored blue, yc. doxes: ca,dua/4: orange, red, and yellow. What is theydoa/xc. ue:csa d: ,4ir rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars sof(f .c 51cfc)wy-ep on a plot of

  A white dwarf star with a mass equal to thu. iw.sh)y,- yoc/avz va.q t,at of the Sun is about the size of

  The Chandrasekhar limit of stellar i .+5vb+un+uwv7cjh pmass (below which a star will collapse into a white vb7+ui5p+nhj uwc+.v dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought tthg e0clm9f-;o always result in

  Black holes

  Pulsars are rapidly spkd:fhoilr ():inning

State Einstein's principle of l),rb0a1 m* l*mbb )rbacxyz/ equivalence.

  The Schwarzschild radius of a bs ob3g , 1o/nb)sml9eklack hole is that radial 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 theory. It can be k, boss9 1gbn3ole/) mcalculated 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 inq3z0ia a6 dyes00i t1u the visible, and the source is mo3as6tz1uy0 i0ead0q i ving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of abvy2 p quaz f0l5ti tg yg32i5tl:(a.b65s:bbmout

  The Sun has apparent brightne7 iqhr 1-,-j xfe6mbiqss 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 f;wf; 77yo4 lq5 ncaenluminosity 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 r9r zk 3zdly 3da/gv;t;y z.h;wadius 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 rad1ykpyuf a /8e7ius 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 is Eartl),c6nlaw aj n+(:1wub 1njshh's nearest star at , nl)j6 (1w :w nacals+nbh1uj4.3 ly?

  The apparent brightnessdm u:tya8jn:f0r j 1 v)r.qfkz4pv2 q9 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 ofco2 40ni*)aw7: t wzzoxj 7;spzaoi v( the universe is 1/H, where H is the Hub n72jta4wo * 7a c;zzswx zio:0)pivo(ble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving ; mjp-6md9eqac+b-h z ) q-wwoaway from us at 1.0% of the speed of light, how far away is9me)j- a-6mp- c ;oqhwq+wbd z it from us?

  Estimate the speed of a galaxy that is 10 billion light-years aw6s;*o5z e6 4z6)f zkvzinpbat ay.

  Estimate the observed wavelength for the 656 nm li9x )( hh3yhscmne in the spectrum of a star which is 100 million light-years from uhs(9)h3y hmxcs.

  About 1 ms after the Big Bang, the temperature of the uni4fq0jy ai00 ,ag5/fa5k 7 c wch4ympsbverse was about 1013 K. What energy (in eV) does th/4iy q5yaw hbcm0 507 4fjgca0 f,sakpis correspond to?