The appearance of the great range of brightness am0i5oh hfe ei)b8rg+m2ong stars is due to

  The absolute luminosity for most sd.i c ue.vef.d95gc;j tars depends on the

  Four different main-sequence stars are colored b7. /2b *hn -o- /afwqozzyexjalue, orange, red, and yellow. What is their rank from co7/2 j*oyfb-w /haza- n qxzo.eolest to hottest?

  A Hertzsprung-Russell diagiwq3j4pb *s ,fram shows stars on a plot of

  A white dwarf star with a mass equal to th2(oxtlh r ti,(at of the Sun is about the size of

  The Chandrasekhar limit of stellar mass (below which a staribn 0:ppj4y .-pj u;ce will collapse into a white dwarf) is, if the mass of our Su:4ypu0 -n ;ci.ejpp jbn is M, about

  Supernovas are thought to always result062:xqk,9nkbvj;fum d x f /lmd wfz0+ in

  Black holes

  Pulsars are rapidly s v3v6r7ume0 gcm6c5d gpinning

State Einstein's principle of equivale:mzyh f k (7f3yjh1fi(uujz6 vny1 3f9nce.

  The Schwarzschild radius of a black hole is that ,m jcewabs,q jn t818;radial distance from the center 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 theory. It can be calculated from a star;8j twj81qamc, enb s,'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 parti:4u3gpr7bzru cular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be z7u3rbg r4pu :shifted toward the

  The cosmic background radiation cor341-mbr:zfgh v ifd5 cresponds to a temperature of about

  The Sun has apparent 4q(us0c 5(n;cjhtkl xbrightness 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*djl51n ,ew ej4 3ign)1ltd3nw vhbb* 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 d9l89wx )p(cfvkwd m, 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 l)/qf+lu- j0xn us:,u 1ahxkna 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 i-d()wbrw/a j:owwh h *d/h4;nl1yribs Earth's nearest star at 4.3 ly?a:o(rww hbhd4/hdbiw) lr;1nw-jy */

  The apparent brightness of a s4 jp2s4ur jq)vtar 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 ilp ;l4w1t71kya bsrz/s the Hubble constant. Taking H = 20 kya1 s 4;1pkwzl/btlr7m/s/Mly, estimate the age of the universe, in years.

  If a galaxy is moving away from us at 1.0% of ami 3hf3kzcmstyu9( i2 0d q4oh/ 11 q)fvmj8ithe speed of light, how far away is it frooc /u11vfz mfh04k t)hiqdm iai9j3 3s (28myqm us?

  Estimate the speed of a galaxy t n(4ah2alxb.-c)ffwahat is 10 billion light-years away.

  Estimate the observed wavelength for the 656kwmzybv(hy488+0q+iowz)j - kxgwr6 nm line in the spectrum of a star w8ybr4xy0k ikoq )gv+zw6w- zh8wj+ (mhich is 100 million light-years from us.

  About 1 ms after the Big k8v8dd d,pji/Bang, the temperature of the universe was about 1013 K. What energy (in eV) does8j d/ 8vp,dikd this correspond to?