The appearance of the great range of brightness among sta*j1i-qny k 8rb+ nh6wers is due to

  The absolute luminosity for most stars db4rqjlwv 8v-k2f( b 2uepends on the

  Four different main-sequence stars are colored blue, orange, red, and yell 8t32n(j :wqd/ lpk./uqjua zsepc ;s2ow. What is j/ ejtck:psul/2.qzd2;qsn 8ap w( 3u their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows /mt6 ho z1 g/xz7qj u:pgs tvkj5.51vkstars on a plot of

  A white dwarf star with a mass equal to that of the Sun is abomisg(g-(jl4y ut the size of

  The Chandrasekhar limit of stellar mass (below which a spvs.wc9v, l3star will collapse into a white dwarf) is, if the masswvlscsp,39 v . of our Sun is M, about

  Supernovas are thought to alwq 0f i;uv9z:(h z-m 2dikefxk7ays result in

  Black holes

  Pulsars are rapidly sp;3e mozr(q1q s*lo-f binning

State Einstein's principle of eq;93,.a dp2o4xvz bdu1qan wb nuivalence.

  The Schwarzschild radius of a black hole is that zdailrvz e rb7 yxpz5t 5 (np0oy6))e1i862 ieradial distance from the center of a sphere within which not even light can escape. It was first discovered mathematically by Schwarzschild in 1916 after l06p (b 6 5ezydytri)n8v zi5ezi7pa x)r eo21Einstein 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 wavelength in the *2 rq qf2ipfv3visible, and the source is moving away from us, the color of the light appears to us to be shifted toward theqp23 2fv fqir*

  The cosmic background radiationj vfdt0u 7i;lqqp 2 5w3(lac0r corresponds to a temperature of about

  The Sun has apparenta2* x.czv7k. uld5sws brightness 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 lum5v r c4:msr)eginosity 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 mean radi: g z;-qxl2wpkaxvsp)zu 4+q0us 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 alck8ln vq( ij(4bx4sqxlv7 14 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 is Earth's nearest kl7yzk9kb:e- star at 4.kl: k79ezbk y-3 ly?

  The apparent brightness of a p;cd)8jg ;- sdga;rcp 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 age of the unive rb7ctg6z,1fa rse is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, b1za6 f7g r,tcestimate the age of the universe, in years.

  If a galaxy is movinkbmskzp57q- :+ 8n cn-c jv: ;p4tnzqpg away from us at 1.0% of the speed of light, how far away is it frp npsz8 c :vk: 7bz+n-q5;c4-pmjnt qkom us?

  Estimate the speed of a galaxy that is 10 billion light-years awul :wz4eo;wgdpit q17h:j )o/ay.

  Estimate the observed wavelength for the 656 nm line in th zd*qzk/bnj3uo + u, if1xss+.e spectrum of a star which is 100 mi uqi+ b+s/ ,x.kjn sz1u3d*fozllion light-years from us.

  About 1 ms after the Big Bang, the tempv( tt6 a1kjp d2otf 7s3lpy9v0 nik(4xerature of the universe was about 1013 K. What energy (injipkf (4do36 nt7v(s1tk09tp2vyxla eV) does this correspond to?