The appearance of the great range of brightness amoncvbcg9nfda o)3 / 4tp*9 s.m( agbqad6g stars is due to

  The absolute luminosiwy*3vq+t n r+j9cqe 1bv1ycv,ty for most stars depends on the

  Four different main-sequence stars are colored blue, orange, red, and ye n ed p6hohc,uv5+e/o7llow. Wce,h6odn 5oe+ h/vpu7hat is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows staq lgl:t0g eq5uqk+/ u2q*zl6fpsw.)m rs on a plot of

  A white dwarf star witkg1;fn9ii384 jlgp vg/ sy9avh a mass equal to that of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a star 3veazd8)tfp2 will collapse into a white dwarf) zvpdf 8a2te3 )is, if the mass of our Sun is M, about

  Supernovas are though:ciz 7peok8l/ o)b/8 in 6lpo2kfm8xbt to always result in

  Black holes

  Pulsars are rapidly spinn cupb /*ih-hqxj/9 hkr s;tr2*o :cbs5pvls66ing

State Einstein's princip aq bup:2np0gbl3 :ly7n5gp-*zqcda6le of equivalence.

  The Schwarzschild radius of a black hole is that fs.jn2zm, lirqiqu/cj1,o s(t vx8+*d h2 s3iradial distance from the center of a sphere within which noti ,s ful, +ht2ijomi2 ds .qjnxc1(s8r3v */qz 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 i j r0m4a,5brf/ cedy,an the visible, and the source is moving away from us, the color ocrf arjmy4/5 ab,e0d ,f the light appears to us to be shifted toward the

  The cosmic background radiation correspo9(u bfhur1jo9ns xj gtmf:e98f7tj 08nds to a temperature of about

  The Sun has apparent brightness at E0dia j-e5 ah,o51 czu 66qzukjarth ($1.5 \times 10^{8} \; km$ 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 t1xd2i1kk t:g3.be7llsr-j vs he 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 wz mf-*didsd6., tmu ,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*76n4m tqd :mutv/zw k 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax angle for Proxima Centauri, which is Earth's n6z09uqy y0t 4p(kdm7dpn k 5owearest star at 4.3 t ym764d0k0u q5p opnk9zw (ydly?

  The apparent brightness of a s8t-vp6b/zmm ;7mki pbtar 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, wherei01 s3) n5bjakhakctl6 l/g9p H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in years ai/1kjabg 69kp5ntcls3)h 0l .

  If a galaxy is moving away from us at 1.0% of the speed of light, how far awjb fta- l-n qvi5a0bsi;ak98vkku7 dj)f7.z/ay is ia f)7alidb9a bjkfv- q tv7j-sk.5nukz80/i;t from us?

  Estimate the speed of a galaxy that is 10jp3m ;p6m-ui o)6tvs11 e kqcl billion light-years away.

  Estimate the observed wavelength for the 656 nm line in thlx18gkitcg .i14 gql. e spectrum of a star whick1iggcx1 .q gltil. 48h is 100 million light-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about zohb w-7nzw -e05- zh0w m6kfy1013 K. Whbzmf6z-0hn w-0owk 5 hy7w-ez at energy (in eV) does this correspond to?