The appearance of the great range of brightness among stars idqk:,/ et3pj is due to

  The absolute luminosity for most st3e0j tavvi9crw o0*y +ars depends on the

  Four different main-s2ov/ dqb/2i awequence stars are colored blue, orange, red, and yellow. What is their rank fro2vwd aqb2oi //m coolest to hottest?

  A Hertzsprung-Russell diagram shows stars on a plot nynxxlhx02r(gx o0y )(,;m riof

  A white dwarf star with a mass equal to that of the Sun is about the qd1-b:- oeaoej *9ije4fv k; tsize of

  The Chandrasekhar limit hv ,9xii u+m:gof stellar mass (below which a star will collapse into a white dwarf) is, if the mass of our Sun is M, abou+humgi9xiv , :t

  Supernovas are thought to always res 1 io(j5ayc8pdw2pdwww4n1 a1ult in

  Black holes

  Pulsars are rapidly spinnihn qac7cux7)/vkk q/3m gw)(rng

State Einstein's principle of equif dw duue+.7-dswo)z 6valence.

  The Schwarzschild radius of a black hole is that radiaisggp e3:ob: )l distance from the center of a sphere within which not ep )3oib:e:gsg ven 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 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 lightbehp2tp:8ph u0sr.d ,*2hl ft of a particular wavelength in the visible, and th*p2bf.l0hpuhtr8dt,h:e2 ps e source is moving away from us, the color of the light appears to us to be shifted toward the

  The cosmic background radiation corresponds .ov io -r75ifrxhkj:1 to a temperature of about

  The Sun has apparent brightnessgp(4(lzcq hn/0;x6rcv/qti o 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 u hkpg/c;85(n-s jd vuluminosity 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 o 5fgm8.t 7s/bhyfyhn, 2zdoy7 gz0gj *f $1.5 \times 10^{8} \; km$. 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 ha z6 +mkw,mcs9us 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 af /v0 d1j2mc:f 8p mzivqn0rm*ngle for Proxima Centauri, which is Earth's nearest star at 4.3 l n jz:fd/pq2m8r1fmic00* mvvy?

  The apparent brightness of a sf i;(zmk3 3ve3lorrv8o;9 d bitar 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 oo ehp icr2pk/w0 m5i4e(2wj4pf the universe is 1/H, where H is the Hubble constant. Taking H = 20 km/s/Mly, estimate the ag4 je2c ( w2krihop0pe5 p4mi/we of the universe, in years.

  If a galaxy is moving away from us o . bzj0 .rw9e0n,vr5tx bb7toat 1.0% of the speed of light, how far away iso jtx0795.vw,o 0brneb . trbz it from us?

  Estimate the speed of a galaxy that is 10 billion light-years awapu9 4ve3 yuahbwc:1 au/nz34ny.

  Estimate the observed wavelengto -uu81b vm*hrq2nrn+ h for the 656 nm line in the spectrum of a star which is 100 million lig 2 m+rr-unbo 1n8vu*qhht-years from us.

  About 1 ms after the Big Bang, the temperature of the universe was about 1013 Kv+agwvo/2c92 bf 8t;pe h1jqy. What energy (in eV) does ea hco1fb 2g ytq8 p2j+/9w;vvthis correspond to?