The appearance of the great rnce 0gc)6t70 epqm p0fange of brightness among stars is due to

  The absolute luminosity for most stars depends on z0cgj+* .mrt1d mhl2ubw-a (vz /b qp,the

  Four different main-sequence stars are colored2r dc2bakz91 c blue, orange, red, and yellow. What is their rank from co1 krcd 9z2ab2colest to hottest?

  A Hertzsprung-Russell diagram shows stars on a(x t rny-c7q/alkai0ou-n5/o plot of

  A white dwarf star with a mass equal to that of th)u(lq2clf 1yfi3nt tso y)m9-e Sun is about the size of

  The Chandrasekhar limit of stellar mass (b7imyi d8-zru09 qq0,p v)edls elow which a star will collapse into a white dwarf) is, if the9 zd0)u07qdpvl, sqmeri iy8- mass of our Sun is M, about

  Supernovas are thougri)acl4f2ah o)v; h +sht to always result in

  Black holes

  Pulsars are rapidly spi(9ztj74tt(m ij hyu0/s ocmgs-zw+n 7 nning

State Einstein's principle of equival+zqkcpp .-u azwopl)**xm( m2ence.

  The Schwarzschild radius of a black ht5t;zhtf 1yh:0*vflcm o ;yw .ole is that radial distance from the center of a sphere within which not even liz5y:f*tm yht.;10c;wf o lthv ght can escape. 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 the visiuo g7dha( nb9-ble, and the source is g7o hnab9-(ud moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation correspond/bchkma.y,d4 -c /zzls to a temperature of about

  The Sun has apparent brjhuj29tz1z2f 8 upn4z8nbux)t.5 xboightness 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 .yc3d)glk yf2*p5ytz luminosity 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 radius ofkv((qyk+nn2 y $1.5 \times 10^{8} \; km$. 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 ag720ah2to+uq 0tji +zg m wpl- 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 nezp(j7: h yqv6 f 2caj,pzu(4tdarest star at 4.3 ly?ua((z y,h2fcdz 6jj:tqpp 47v

  The apparent brightness of a star is .zp/*jlaymv9 e v4x)d$1.0 \times 10^{-12} \; W/m^{2}$ 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, wws qprz,5 h pxtvvwh1;)aa0*7(vg .zy here H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age ofr0pavpx ,q*.; v1y(w w5h) vzaz7sg th the universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, how far away 7/ 9:i tbicxzk*hwxzjq1t*6 c is 61i: ztcq*cx*hx i9w kt/zbj7it from us?

  Estimate the speed of a galaxy that is 10 billion light-yearsazaidm s: oz+30q)v7d away.

  Estimate the observed wavelength for the 656 nm lw:fa-ivx w9ytb99j.nine in the spectrum of a star which is 100 miltby9 :jx9vi f-wwn. 9alion light-years from us.

  About 1 ms after the Big Bang, the temperature of the univeru4gd3 t dj.x68nfw1d3j t9yvrse was about 1013 K. What energy (in eVwt3tu6ngd4v8 jd31 xyrdf9 .j) does this correspond to?