The appearance of the great range of br,8;v kgbbb u4tjilh-1ightness among stars is due to

  The absolute luminosity +e-aqo- a* b( th,hbe8vo o (ry5 x1hrn1in2dofor most stars depends on the

  Four different main-sequence sun) 6ztew .:rad9,gzyeu uk;x:z9xs : tars are colored blue, orange, red, and yellow. What is their rank from coole6, )a:zu; u ezkxystgz:x .n9: uw9drest to hottest?

  A Hertzsprung-Russell diagram s1 ff:)gv0vyrg hows stars on a plot of

  A white dwarf star with a mass equal to that of the Sun is about hz8a6zea07cr ; 8 nomtthe size of

  The Chandrasekhar limit o.5ogt1m:/nm fwh ou)j4; 9gr*n ff qztf stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our S.gg * fzt:n o 1ohq9m rtf54n/mfuj;w)un is M, about

  Supernovas are thought to always result z+,sd ):ha*n3jppfp uin

  Black holes

  Pulsars are rapidly spin) g 0m1/ljpzm 9nsmp-b;,ffzzning

State Einstein's principle of +6f9 klj)hn 2jwa eoik9gh*q-equivalence.

  The Schwarzschild radius pkxe f-094vrw of a black hole is that 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-xf9v p krw40e 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 visiblklr7j 4bs(b 8be, and the bs(b8lr 7j4kbsource is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temper3h uszwf/)b onvsph,x33b u)s u6e*;lature of about

  The Sun has apparent brightness th(np3e zc6. ;v lf4plat 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 Stbhx. v(ocu0.x m0ds/ un ($1.5 \times 10^{8} \; km$ 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 mean radiu0zs p;xgunufu4,q z*ke7j na5*p q7b,s 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 radiuz :hp. bb0k3 ew*xqed;w1ckz)s 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 nearest star an/ uvk7hz59iez9/uk n 57hveit 4.3 ly?

  The apparent brightness of unxz)q v ,;al)coq6*va 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 azv5oc z.y1en2 ge of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the univer1z .2yzecvn5o se, in years.

  If a galaxy is moving away from us at 1.0% of the spey/jir u e7rd8ibh3:z3ed of light, how far away is it from :i z/ ri7r3h38byejduus?

  Estimate the speed of a galaxy that is +:b dpk;j -iuz2 xwa(*drq5z yfjg-0w10 billion light-years away.

  Estimate the observed wav*xch c +90z5pr3jq id. l(ilpfelength for the 656 nm line in the spectrum of a star which is 100 million clhpj+zq9d i*l 05fr(xc.i3plight-years from us.

  About 1 ms after the Big Bang, mb7mx, cv w6q14tcw8vmvk ejq5.t9ce31m 4ad the temperature of the universe was about 1013 K. What energy (in eV) doec,jv mtw .4cck3m1a86e4m1e q5v btq7m9x vd ws this correspond to?