The appearance of the great rai )tgp() y0haenge of brightness among stars is due to

  The absolute luminosity b;:t c.blla04, xa4uhl 8lcrpfor most stars depends on the

  Four different main-sequence stars are colored .pnnvx3 s sx*37 p,vfvblue, orange, red, and yellow. What is their rank from coolest to hottexvpnfp 3v3.vs, s*n7xst?

  A Hertzsprung-Russell diagram shows stars on a p7jmhjy 3:w jwmt;iin/8af t (5lot of

  A white dwarf star with a mass equal to that of the S dn7w :yixyrdwotc)0w) n*c1su +t5o7 un is about the size of

  The Chandrasekhar limit of stellar mass (below which a star 3gfzre pmb34 +yyx7jk( 8pj d(iw0db:will collapse into a white dwarf) is, if the mass of our Sun is M, abgpd(( : bpywfizk3x 4jdb8 j+7e3 ym0rout

  Supernovas are thought to always result i.jhzp ru7u1qg 0rllim* 3* rt-) jar3on

  Black holes

  Pulsars are rapidly spi0oi b 5qq6rx+pnning

State Einstein's principle of equivalence1f+i(/j ) +jbucwwdiz.

  The Schwarzschild radius of a black hole is that yxbt ,iti5;py5x - 3woradial distance from the center of a sphere within which not even light can escape,i o 3ywpt5 xyb-;tix5. It was first 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 particular wavelength in t iby i9kh-,k/she visible, and the source is moving away from us, the color of the light appears to us to be shifted towardb,h siy/ik-9 k the

  The cosmic background radiation corresponds to a temperu p+jb5na q7c)ature of about

  The Sun has apparent brightness at Eart 6jz72zn-gymo xnkrt3, l) er5b.e9h ch ($1.5 \times 10^{8} \; km$ 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 thewo/gs*j,t8 +mgu15nibfsvz 0z;w 4ty 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 radius wo-fym;-cp7zjdk8 8o zs99jvof $1.5 \times 10^{8} \; km$. 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 hasao y/:6u.: zd,9ox pkpi0 owmq 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 angle for Proxima Centaurisba,b.zcn4;w o ;dki 0, which is Earth's nearest star ato;;bw0ak.zc 4i bs, nd 4.3 ly?

  The apparent brightness11-xmh /cgtgj of a 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 universe is 1/H, where H is thedeh+muvrca6qn p d2kcvo(5fk1 +r8 d)hk1m6: Hubble constant. Taking H = 20 km/s/Mly, estimate the age of the universe, in ye1r kreo5ka:ukfd )v h +v8 hdd6n+ c12pcqmm(6ars.

  If a galaxy is moving away from us at 1.0% rkx7xn0 t7( hqof the speed of light, how far away is it from ukxnh (t077rxq s?

  Estimate the speed of a galaxy that .t-t ky(qo :rmis 10 billion light-years away.

  Estimate the observed waveleng-yklyr ; n(9gf5lza7 ath for the 656 nm line in the spectrum of a star which is 100 million light-lga59yf7 ( n;a ykl-rzyears from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 101s 4ti+.na pe- gdxq,t*3 K. Wdx* pet.- g+isat q,n4hat energy (in eV) does this correspond to?