The appearance of the great range of brightness /nyuk2,rgf; zg0d*un among stars is due to

  The absolute luminosity for most stars depend /n1ngs9z f7aps on the

  Four different main-sequence stars are colored blue, orange, red, and yellow. Wyvi/5r*4xp g nhat is their rank from coolest to hottest/xp5 iv *n4yrg?

  A Hertzsprung-Russell diagram shows stars3 cgemqvp)x a51+a 8if)kpxt6 on a plot of

  A white dwarf star with a mass equal to that of the- hq :giwyqc+: Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapse into a0q j hi9/a 007zyfsguo whit9/iaf7 0yg0qsoj0huz e dwarf) is, if the mass of our Sun is M, about

  Supernovas are thoughke o ./y6m3xgw7hd b+qt to always result in

  Black holes

  Pulsars are rapidly spinnp *fc wzc:e. to+4ywo/ing

State Einstein's priny gi,4-axyp um4sj xe/.5s jh9ciple of equivalence.

  The Schwarzschild radius of a black hole is that radial distanced7yl6.ua9 a3rt t k+dz from the center of a sphere wit7. rlutd dzyat96k a+3hin 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 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 the visible, s;;yx suve) s2b*pf1 nand the source is moving away from us, the color of the light appears to us to be shift1x;2 e ;)*ys nvbsfupsed toward the

  The cosmic background ra i5y 6z9 -97ia7lc o)fmv s)y5kmxcaqldiation corresponds to a temperature of about

  The Sun has apparent brightnnc zcp0z.xpnwbo 48 4qmn (k::szs)w+ess 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 that of the Sun 1a v55q qcly9o($1.5 \times 10^{8} \; km$ 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 sbunp.m c6w+2wa5(qczshuc7o3- 7r rmean 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 med 93hub rd 8m4)py:jonan 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 Centauo-w;rahgm* ;. az ,nupri, which is Earth's nearest star at z; n.,hoa*u ; -mpwgra4.3 ly?

  The apparent brightnu6 )*q6hya gr 3sbu.pzess 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 of the universe is 1/H, where H is thed9 0 oibehvb:zz 9dj3zpo 9yp-d:8 y0t Hubble constant. Taking H = 20 km/s/Mly,o9:ydpjd39bz y e9v8 ohtp0 db0:iz- z estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how fak8gc qr/9tzr3d) i cyt2ca+7wr away i c awkrt7gy t8q9+d2)izrc c/3s it from us?

  Estimate the speed of a galaxy that is 10 billio8uhu;(t q vd0tn light-years away.

  Estimate the observed wavelength for the 656 nm lineuoo2 luy7e 19+u/ kn 3,pphenw in the spectrum of a star which is 100 million light-ye,o7wluyopn3uhk1p n 2/ u+9eears from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 K.1gktbft pt3: 22gvgz- What energy (in eV) b3ttk: tggvz212-pf gdoes this correspond to?