The appearance of the great range of brightneslixttb.9+km u 29s:b hs among stars is due to

  The absolute luminosity for most stars depends on therraxirx8z1r:b qpqa ,mb. 0 8/

  Four different main-sequence stars are colored blue, orange, red, and5 :hob7o la++j d9qcyf yellow. What is their rank from coooh7qc y+:lbfj+9d o 5alest to hottest?

  A Hertzsprung-Russell diagram shows stars on a ploav wc29 pxy jw)wic22 :o ijk/6fz4 zz.5fuc;et of

  A white dwarf star with a mass equal to that of the Sun 8n8yg-qmvo- u is about the size of

  The Chandrasekhar limit of stellar mass (below which a star will collapsscc gg 9u entb:t*8/zn9yq. d:e into a white dwarf) is,/:q 9g9n z. c8 ytb:g*tucesnd if the mass of our Sun is M, about

  Supernovas are thought to always resul wslcr-pj)a;tx2 :2tkt in

  Black holes

  Pulsars are rapidly sp 6. :) x.jo gv1b8;2lbzcp adwdcnlhb-inning

State Einstein's princ 9q)7gs8pw8beala q-+q ,kccuiple of equivalence.

  The Schwarzschild radius of a black c d ;*np2m ei*ofe/kt(m 65kslhole 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 191(te 6lfp5mk ;m ced*o*ik/n s26 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 wave ; y;1xpl)ltu:6vy ypulength in the visible, and the source is moving away from us, the color of the light appears to us t)1yp; xypl ;tyuu:l6v o be shifted toward the

  The cosmic background radiation corresd ydu5d+pen-l 0u: 9vvponds to a temperature of about

  The Sun has apparent brightness a0 r2pkcgz5n4 5fu 9eiyt 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 ucy,+r +x4) lov)gjd/m1xg* leh/jkd(en(s w the 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 a mtco td oaa4*q h/+g7m)ean 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 ha+s, qv1w rwe7oyjpy8,s 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 ly? (1 ly = $9.46 \times 10^{15} \; m$)

  What is the parallax anitwxc )i* 4ui:gle for Proxima Centauri, which is Earth's nearest star at 4. t:4x*c uii)iw3 ly?

  The apparent brightness of a star ishgp0,xs2h xm* p6o tf, $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universe y fo5 e0667vohfx ;bpthrm ;1cis 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the uni6 h;ve;ht ff0pm 5bo6 oc71xryverse, in years.

  If a galaxy is moving aw75j*q q m /cghnd8w;n) l2sccyay from us at 1.0% of the speed of light, how far away is it from u2*gd7 wqjnlys c/ h;c)q58mn cs?

  Estimate the speed ofc)6s rdgl)phdzlm2f 6mq ce3ct-72l63vwc5 r a galaxy that is 10 billion light-years away.

  Estimate the observed wavelengm n0wwvq .9-mvth for the 656 nm line in the spectrum of a star which is 100 million light-years from uqwnv9m0.v w-ms.

  About 1 ms after the Big Bang, the temperature of the universe w6 fv(gd-qua; r:dcuzl *jeu;+as about 1013 K. What energy (in eV) doe* ajcd f :;;e v-lurgd(uz+6uqs this correspond to?