The appearance of the great rangel- kk0b j*nmg2 of brightness among stars is due to

  The absolute luminosity fugi 0ks lc+v4lf60hszu s3rj5-ee e19 or most stars depends on the

  Four different main-sec7 -m8qn5 fy;vzga 2fo5cqj k*quence stars are colored blue, orange, red, and yellow. What is their rank from 72kj*;-cq5yozvqf5gn f8ac m coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a 8ftv s9 sh9iosm9th)oh6l v/.plot of

  A white dwarf star with a mass equal to that of the Szq 3huld ;4(k ;vd2zyiun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will col6p9xkp4c ,lmiq,;pam0xp l .ilapse into a white dwarf) is, if the mass of our q ,,ppmpx0. li9kxc m;lpi4a6 Sun is M, about

  Supernovas are thought to always result+slifhi47sh 1*bdz k( in

  Black holes

  Pulsars are rapidly spinnin jd akncy70o65g

State Einstein's principle 6+iivc ,fqlh e3l( xlq4jpa u,:cvh4, of equivalence.

  The Schwarzschild radius of a black hole is that radial di2jk t /oq*fx;ibc c34wstance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after Einstein publik*f4;it bx co2 3q/cjwshed 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 wavwysoe1t .s16 delength in the visible, and the source is moving away from us, the color of the light appears to uoe wsd1s1t6y .s to be shifted toward the

  The cosmic backgroun8v afw:g+x)xy p/k, 7p4tlh xud radiation corresponds to a temperature of about

  The Sun has apparent brightneq)acb95qp+ bkpil+ 9t ss 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 Ssenzh3qf*3 b yb j43d4un ($1.5 \times 10^{8} \; km$ 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 dh :)-k5oclc mmean 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 mean gf9li x /6rb .dida;m(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 forw (h.0:d *0fogv vn 12uiezfum Proxima Centauri, which is Earth's nearest star at 4.3* :evhv( mfu 0go12 fdui0nz.w ly?

  The apparent brightness of e/40uq7 g ii)t;vjgiol9ew6z 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 3lke;a:hisxd 0 za88*bmnvb) the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in3ve;mzhkb :a 0is)ba*x8d8l n years.

  If a galaxy is moving away frokxt4 bvt5 kfodaz1zz zm*4hgtlbd530 .f6n2 7m us at 1.0% of the speed of light, how far away is it from us?f 1zzv 3*hbk6zfdxa4 5z40g.o btt7n m2kdlt5

  Estimate the speed of a galaxy that is 10 .rmhg2mn 2x(tbillion light-years away.

  Estimate the observed wavelength for the 656 nm linez /v )+aqy)lak in the spectrum of a star which is 100 million light-years )klqya z) v/a+from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 +ti- abd7uw+ annck2zae8km+2;2w wc K. What ene +2b dk i2+akc8w -zeamunn a;w7+w2ctrgy (in eV) does this correspond to?