The appearance of the great range of brightness + /ecpgb6:rpv8+ ypkay)wz*r among stars is due to

  The absolute luminosity for most stxw q1e-d, rtu8ars depends on the

  Four different main-sequence stars are colored7f m8*j)6ho)brfsq lj blue, orange, red, and yellow. What is their rank frhj 6o 7q8blrsj)f)f* mom coolest to hottest?

  A Hertzsprung-Russell diap/p bfk;n)f5 uzb,g+ugram shows stars on a plot of

  A white dwarf star with a mas/,nv/cof i(e js equal to that of the Sun is about the size of

  The Chandrasekhar limit of steo/7ks*glm :de+kc:dj k/+cfwllar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M, 7d+/+*omfkce/g s:w kl:c jdk about

  Supernovas are thought to always result inb ( qffog3yjv5a/4f u.

  Black holes

  Pulsars are rapidly spin:arqdty4xw+w 21 sv)h ning

State Einstein's principle of equivalenw zaj 1y+lcwi2yok*bm. 94 (ltce.

  The Schwarzschild radius of a blaj25 pnpjbokpc52 7b5h9 vt/g fck 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 cang 92pvpjpjt5/55o2 nbc7 fbhk 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*bq1 q+ t/kxxtmnqrbdqm;ufo*r6 0:* length in the visible, and the source is moving away from us, txo+*dxt 6b0 1*tr*kbq frq/:n qmqm u;he color of the light appears to us to be shifted toward the

  The cosmic backgroun;)yb wtzvhk a9p87vk(d radiation corresponds to a temperature of about

  The Sun has apparent brightness at Eartw v:kz*6b7o gth ($1.5 \times 10^{8} \; km$ 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 lf5 ;gw zi0 x:cf6;xukeuminosity 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 has a mea:bhav ;q2th jr4rn) j/n 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 ag- uf1 g08(.wlr0h3df1;kbg vsqm xfss f2) u$1.5 \times 10^{8} \; km$. 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,(pde, z t+xt+c2xp;cq which is Earth's nearest star at t ec2;t, z+ pcd(pxxq+4.3 ly?

  The apparent brightness of a ;sgq1 cahg, 0e7ybl 3 5z:ozrdstar 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 agtsv,g 1/t9u6 )hmuhje e of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of t/96 ts1mh ,vghu)eujthe universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, hoo6 ub-87i:d4qadqd kfw far away is it from a6f47q q k:i-obdd8duus?

  Estimate the speed of a galaxy that in3d fkd, q, )4y4c+:owxma8:r9 cr.tahx bahfs 10 billion light-years away.

  Estimate the observed wavelength for the 656 nm line in thet3 /1xepp (,a eja-q9we1qdx.km ,x ri spectrum of a star which i damk,,xpte(1.-xaqei13rjqpex/ 9 w s 100 million light-years from us.

  About 1 ms after the Bi9n xc)+zrtq lr0cua4( qy28zdg Bang, the temperature of the universe was about 1013 K. Wc) yrnu+(q zzq x89rc204ad tlhat energy (in eV) does this correspond to?