The appearance of the great range of brightnesskdl 5h )hm*xxb 7+kkg+ among stars is due to

  The absolute luminosity for most stars dep0e rwiz (og )8;gavq2cends on the

  Four different main-sequence sta rnpm/9: x;45 *f 6ltqx neui)dssi;aars are colored blue, orange, red, and yellow. What is their rank from coolest to hottesiq/ : x nl a9s6i4ame;fs 5td)ru;xpn*t?

  A Hertzsprung-Russell diagra-4eg0rz6e)ufrahs/gp* e zb ,m shows stars on a plot of

  A white dwarf star with a mass equal to that odrqc h,gcl-ce5 d+p+6rr8i 0 qf the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will col5ek tv9b)au+glapse into a atveub5 9g)+ kwhite dwarf) is, if the mass of our Sun is M, about

  Supernovas are thought to iruv r q 9sl(*635nsosalways result in

  Black holes

  Pulsars are rapidly s-p8k+ pg) opb:o -iwm6ue cw8upinning

State Einstein's principle *3;vv* hr ip g*qywxqs1:5yqfof equivalence.

  The Schwarzschild radius of a black hole is that radial distance from the cens9hvmx : :gd3nter 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 thehxvsg9n::m d3ory. 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 pa wv-t) t3/1maxdfe; e7,ihumn rticular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to/-)e xe3dwa,h; m1v7t tiufm n be shifted toward the

  The cosmic background radiation correv(o vr/ cerz./sponds to a temperature of about

  The Sun has apparent br pg z 1ha/akql3c-.xc6ightness 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 thaty4im/ g0g4x*lbh,n s+n0* p7j 2usynffaosm 6 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 *rt*tf7qap, xpytu(*a 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 km?

  The Earth's orbit has a vfqwey;(3wko635fl 0v igm. cmean 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 kt q9e;e ;)tbgir4b t,for Proxima Centauri, which is Earth's nearest star at 4.3 lyr;;9gt b qkb,itet4e )?

  The apparent brightness of adrg,cbdh :c+wi/eccl5*2 3 qc 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 1ff ) (h8*gx*tn;jzzx rh9gaethe approximate age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in *() ggzxn1xht*ea9 ;z8j ffhryears.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far awayz3ip7u6r3 w lijd7+ncgdt 4o * is it dngptzijuirw c4 37l6o 3*+d7 from us?

  Estimate the speed of a galaxy that is 10 billion t,9f uqna-f-1pfj9ektcfi4 6light-years away.

  Estimate the observed wavelength for the 656 nm line in the +lp n d,b(:7+(i a*+t5vdb7rzqdda1hge sgep spectrum of a star which is 100 million light-year hq 7lpn, ge as* bd5dt+(z7+bp(vd1+iedr :gas from us.

  About 1 ms after the Big Bang, the temperature of thea,5s)gfn l 96ks-drnh universe was about 1013 K. What energy (in eV) does this a,l 56 nn9hdfg-rk s)scorrespond to?