The appearance of the gr3(qx lg8xx,7 z z1gvhneat range of brightness among stars is due to

  The absolute luminosity for mos2)xu587 wu hioof lrdcl u;(y*0qwhh4t stars depends on the

  Four different main-sequence stars arhum(1 d; vstc-e colored blue, orange, red, and yellow. Wh1-uts v ;dm(chat is their rank from coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot st(r fhigf1d85)xl5bd(yjf3 of

  A white dwarf star with a ma2kjloa22/dqw jmz83v) z 9-rhjvny9 lss equal to that of the Sun is about the size of

  The Chandrasekhar limit:n7gmi dl * vu.q6e6rb of stellar mass (below which a star will collapse into a white dwa*6li7dm :g6vnb uqer.rf) is, if the mass of our Sun is M, about

  Supernovas are thought to ag);y(p nbuz-f lways result in

  Black holes

  Pulsars are rapidly spinnihof 85km k8bng.uvx (,ng

State Einstein's principle of e:kj(s-skw hl.wu7 iln1mh;r; quivalence.

  The Schwarzschild radius of a , jc clsg33aq7ln/+ ;m9ldev vblack 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 can be calculated from a star's mlc, +jgmqdnea llsvv3/793 ; cass 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 visible, a a y9z gpl8angj.v7w(2nd the source is moving away from us, the color of the liz a( 8yavl7p9njg.g2wght appears to us to be shifted toward the

  The cosmic background radiation corresponds to a temperaturia:tsl* (/zij t xkg-4e of about

  The Sun has apparent brightness at6zz*ee kp7vqu: 2zja / 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 luminosity equal to that of the * :fw3i2gt ;s , wcs0qyfh6fjbSun ($1.5 \times 10^{8} \; km$ 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 ha4 q( mbahc d5wmvu(55us 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 km?

  The Earth's orbit has a meanap s4;k+jaf.m*x3 rt 0c5 moj;:6gcoedxv3 fe 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, whyu ;u *2jrmd0 rd*,;qwvf hsu-ich is Earth's nearest star at 4.3 ly,fwdy u-u; j2hv *q;msrdu0 r*?

  The apparent brightness of a star isu9k;a*bg2hi: p+jwffhd4 13+ wwuq ij $1.0 \times 10^{-12} \; W/m^{2}$ and the peak wavelength is 600 nm. Estimate its distance from us.

  It can be shown that the approximate age of the universex* )hob7xn.ze is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the age of thxnx.h7b *)ozee universe, in years.

  If a galaxy is moving away from us at 1.0% of the speed of light, ho+23 eljw6zdmy w far away is it from3dm6 ly+2ezjw us?

  Estimate the speed of a galaxy th.+i+( nthroh aat is 10 billion light-years away.

  Estimate the observed wave ,blejbs7z2j 4length for the 656 nm line in the spectrum of a star which is 100 million light-years27 j sj,blbze4 from us.

  About 1 ms after the Big Banrp 7hx-dq07 9azdgf0r g, the temperature of the universe was about 1013 K. What r7g9x0 ar7f0phq dzd- energy (in eV) does this correspond to?