How many neutrons are in a neutron star with a diameter of 42.0 km?

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Homework Help Overview

The discussion revolves around estimating the number of neutrons in a neutron star with a specified diameter of 42.0 km. Participants explore the composition of neutron stars and the implications for calculations involving density and mass.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants question the assumption that neutron stars are composed entirely of neutrons and discuss the relevance of varying composition. There is mention of using average density to estimate mass, and some participants express uncertainty about the nature of the problem.

Discussion Status

The discussion is ongoing, with participants providing insights into the complexities of neutron star composition and the need for additional information, such as average density, to approach the problem effectively.

Contextual Notes

There is a note of concern regarding the original poster's adherence to homework posting guidelines, and some participants express uncertainty about whether the inquiry is a homework problem or a general question.

MichiganSt35
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How many neutrons are in a neutron star with a diameter of 42.0 km?


I was under the impression it was just

(42.0e3/1e-15)^3 = 7.0048e58

but that's wrong??
 
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It's not cool to post the same problem in multiple forums.

Neutron Stars are not composed 100% of neutrons. There is a small percentage of ordinary nuclei, particularly in the crust and atmosphere of the star. The deeper inside the star you go, the less likely you will encounter ordinary elementary particles.

http://en.wikipedia.org/wiki/Neutron_star
 
That is certainly informative, but I don't know how relevant it is to the problem. How is the OP supposed to take into account the varying composition? How likely is it that this is more than just a density = mass/volume problem? MichiganSt35, you need some information about the average density of neutron stars, which is probably given in your notes or textbook. From this, you can estimate the total mass of the neutron star.
 
It's really hard to give advice when posters don't use the HW template. Is this a HW problem or idle curiosity? IDK. It could be a badly phrased or a confusing question. I rolled the dice and decided to inform the OP that regardless of the name, a neutron star is not a big ball of neutrons. The science of the interior of these objects is not settled in any event.
 

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