The appearance of the greaaus0(ma4l xe9t range of brightness among stars is due to

  The absolute luminosity for most stars xy ybiwyx-67x.tw 9/kdepends on the

  Four different main-sequence stars are colored blue,sf)l h,a3(brd orange, red, and yellow. What is their rank from coolestfhr a3,dbl)(s to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot ofm)6 ydi v2oj,n

  A white dwarf star with a mass equal to that of the Sun is about the e:w:y.go,n grsm-: rps g 40ucsize of

  The Chandrasekhar limit of stellar mass (belm iq)o rf 8:z+p1nkpw+wfsu: -ow which a star will collapse into a white dwarf) is, if the mass ofowwsr )z+pf:nk8up:- iq1m f+ our Sun is M, about

  Supernovas are thought to always re usw l:uqj-+;fy:5bkwj px.orsck .94sult in

  Black holes

  Pulsars are rapidly spinninj zjmwn:w( q d3ws :.lxd16d) aj*g)rsg

State Einstein's principle of equivalencf,)r 0jniku k,,ni5chb i7)op e.

  The Schwarzschild radius h6e kajq r0m3t3,ih.clh 27fg0fh a-u 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 publis37i6k ehjght32q ahc, l -u h0m0.arffhed 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 emffhtu 5 dec1(:its light of a particular wavelength in the visible, and the source is moving away from us, the cofe(t :15udf chlor of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperature of abo-on f 6r/71tpt 9/0swtytmp bput

  The Sun has apparent b(oaw4rro xd 60rightness 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 lv+-xzon,w )q ruminosity equal to that of 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 hac d(wp5/lx/xfs 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 mean radius of y t7u* 0h h*wji+amx7o$1.5 \times 10^{8} \; km$. 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 Proxsi;a))4mg( nv9 lcw1lyg7ozj5m - idyima Centauri, which is Earth's nearest star at 445; ()maj gils c9l-zv y)dmw ny7io1g.3 ly?

  The apparent brightness of a +w q,1 5wtw2p p;xtvptstar 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, wo,unygk2h.+e thtl. mqy4 r44here H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of thh4n.e,o4y 2ymkt gh+ uq. rt4le universe, in years.

  If a galaxy is moving away from us at 1a/qet1j + u:uwp **uzum s1xp4.0% of the speed of light, how far away imtu p1ja /:w4usxz*u1uqp*e + s it from us?

  Estimate the speed of a galaxy that is 10 billion light-yea2m va196i6yqkenua w9rs away.

  Estimate the observed wavelength for theo+vh4vl 2zl u; 656 nm line in the spectrum of a star which is 100 million liuhl;zlv 4 ov+2ght-years from us.

  About 1 ms after the Big Bang,/nq7 ozq4j1yu/yq 0re the temperature of the universe was about 1013 K. What energy (in eu14eqn //oz 0qy7qr jyV) does this correspond to?