The appearance of the grenoqka voyw2u3) 5l+,z at range of brightness among stars is due to

  The absolute luminosity for most stars depen s cus1+ku)o+mds on the

  Four different main-sequence stars are colored blue, orange, red,g9+2 9pewu9w ix )phxx and yellow. What i9)iepp9 2gu9wxwxh +x s their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot;y /ix ilf3sd5 of

  A white dwarf star with a mass equal to that of the Sun is aboi8 x3 3bci,tbbt:v2kt paj8z49bnyq/ut the size of

  The Chandrasekhar limit of sth(srjwr3 c g(1ellar mass (below which a star will collapse into a white dwh(r1r (c 3gwjsarf) is, if the mass of our Sun is M, about

  Supernovas are thougwb- c.d5) 7xr5vhj m58hd qyeuht to always result in

  Black holes

  Pulsars are rapidly spinning5v7n1: ykr1o3rh xt xt

State Einstein's principle of equ/w888y .kjx ( l3c bqdnf+xbleivalence.

  The Schwarzschild radius of a black hole is oxr9 v il8h3d/dkb2g, that radial distance from the center of a sphere within which not even light can escape. It was fir3 vlb k2d r/dxhiog89,st discovered mathematically by Schwarzschild in 1916 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:i2v j 7qnq6ky particular wavelength in the visible, and the source is moving away from us, the color of the light appears to us to be ivyq2 qk6j:n 7shifted toward the

  The cosmic background radia.ihjag d)5cg ;0hg y4wtion corresponds to a temperature of about

  The Sun has apparent brightness at Earth7 8cexd :2ipjg ($1.5 \times 10^{8} \; km$ 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 my i7fz s(1-,amiaq)uminosity 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 kcz oik5.+vks k9nb/zm 8u05e 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 rad cuhm73pwq7x e5l 6vu6u7 zuw.ius 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'haa4zi p6mkjrh8 6 (s/s nearest star at 4.3 l(ajih8am6 6/z4sr khpy?

  The apparent brightness of /w+ks z)em5og.66d bcfe8el ia 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 approximaazxui 3n+igfc2w74p4,a px0o te age of the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the u0na pxi ,ioczpu4 a3gfw2x47+niverse, in years.

  If a galaxy is moving away from us at 1.0% of the drfqhq1,42b.ag lob0c c4ku0 speed of light, how far away is it02c0g4f4qcb bd.lo1, rha qu k from us?

  Estimate the speed of a ga)bisa 5k*(g kkug:my7laxy that is 10 billion light-years away.

  Estimate the observed wavelengt9sx 08 ),hzetnmh) ax lka0av61aav;w h for the 656 nm line in the spectrum of a star which is 100 mimn0a z1a0 satwhhv;x8lxv a,) a69e)kllion light-years from us.

  About 1 ms after the Big Bang, the temperature of the univerav 2.fv r6q72kedniv:se was about 1013 K. What energy (in 6 frdq: v.ae2iv 72knveV) does this correspond to?