Astronomy

Question Answers

How large would the Sun be if its density equaled the critical density of the universe, pc ≈ 10 – 26 kg/m3? Express your answer in light-years and compare with the Earth-Sun distance and the size of our Galaxy. ...
In the later stages of stellar evolution, a star (if massive enough) will begin fusing carbon nuclei to form, for example, magnesium;(a) How much energy is released in this reaction (see Appendix B). (b) How much kinetic energy must each carbon nucleus have (assume equal) in a head-on...
A galaxy is moving away from Earth. The “blue” hydrogen line at 434nm emitted from the galaxy is measured on Earth to be 650nm.(a) How fast is the galaxy moving?(b) How far is it from Earth? ...
Astronomers have recently measured the rotation of gas around what might be a super massive black hole of about 2 billion solar masses at the center of a galaxy. If the radius from the galactic center to the gas clouds is 60 light-years, what Doppler shift ∆λ/λ0 do you estimate th...
What is the temperature that corresponds to 1.8-TeV collisions at the Fermilab Collider? To what era in cosmological history does this correspond? ...
Through some coincidence, the Balmer lines from singly ionized helium in a distant star happen to overlap with the Balmer lines from hydrogen (Fig. 27-22) in the Sun. How fast is the star receding from us? ...
Suppose we can measure distances with parallax at 100 parsecs. What is our minimum angular resolution (in degrees), based on this information. ...
Estimate what neutrino rest mass (in eV) would provide the critical density to close the universe. Assume the neutrino density is, like photons, about 109 times that of nucleons, and that nucleons make up only.(a) 2% of the mass needed, or(b) 5% of the mass needed. ...
The nearest large galaxy to our Galaxy is about 2 x 106 ly away. If both galaxies have a mass of 3 x 1041kg, with what gravitational force does each galaxy attract the other? ...

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