The appearance of the great range of brightc v* -vxrdcatc6y7l. -ness among stars is due to

  The absolute luminosity for most stars depenl. , /gjg*c 4xc.c+al05ww wwpzjiagcmdi8(:ds on the

  Four different main-x: hc x6epaz/; (vg;-vay j;uosequence stars are colored blue, orange, red, and yellow. What is their rank frxjey6vzx;:(g -/ va co;;hpuaom coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plo-vx ,5flo(tnn ld5 :;qym*abzt of

  A white dwarf star with a mass equal to that of the Sun is aeiwz,po7wwcl/6r +b 6kc qju g yl69)-bout the size of

  The Chandrasekhar limit of stellar mass (below whi5(z-b((g0scg nfib i ich a star will collapse into a white dwarf) is, if the b( ggfn( 5bi0izis(-c mass of our Sun is M, about

  Supernovas are thought to always rdz+a9ts+x c8eesult in

  Black holes

  Pulsars are rapidly spinningcax. t0;1zxfojb0m+h

State Einstein's principle of equivyog+ o ixgsa(3tirw* ;9vv* ;/gh rnigkml(8/alence.

  The Schwarzschild radius of a black hole is that radial distance from t0sl9fih -nd i *ru+9pgy6ntf5b-vw (ikq5 kw 1he center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in (b99knw vgf*u5 q0t6--d wilphs1kir+ iny5 f1916 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 wavelength in thbp(m 7;y,-wgp,pkywh e visible, and the sourc ,-pbpy 7; mwy,hkpw(ge is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background.1gnzpoltw 3d:)eq x) radiation corresponds to a temperature of about

  The Sun has apparent brightness at Earth.e 4ck7qw m;cp ($1.5 \times 10^{8} \; km$ 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 k 1bmb.2 2gn9,wnh km,flgimw -o8pf 0of 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 rai to.cdx7--j vdius 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 meaa liwe/3z,m7 ejy5g5gn 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 Centaurimkrs :xx65wvz5za 6 g8, 1zkff, which is Earth's nearest star at 4.3 1:5xgza z6mfk,8zrxv 65w sfkly?

  The apparent brightness of a sta k.w4iant38;v1t5eojuvxqmr c p q/11r 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, where H if5:q d l:(bmjgs the Hubble constang:(jf5 dbqm l:t. Taking H = 20 km/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from .wrck)bye0vrh 6el /6us at 1.0% of the speed of light, how far away is it frrey /e.w 0)khbr6lc6vom us?

  Estimate the speed of a galaxy that is 10 billion impl.gp+(iy2 q efg4edv67s 6nne(h h6 wk0u6light-years away.

  Estimate the observed wavelength for the 656 nm line in the spectrum of *h*gx ,k qk;vyv z-8 lpptib3-a star whi 3lzbkyq, v-t*- ph i*kpxvg;8ch is 100 million light-years from us.

  About 1 ms after the Big Bang, the t anlx;t;duki po o1,--emperature of the universe was about 1013 K. What energy (in eV) does this correspondn;i kl;ou,--paxto1 d to?