Errata for Published Version of "Neutron Stars for Undergraduates"

Richard R. Silbar and Sanjay Reddy, American Journal of Physics 72, 892-905 (2004).


It is worth noting that, for us, the symbols k, k_F, etc., refer to momenta, not to wave numbers. Some of our correspondents have been confused on this point.

The following typos were noted by Bijay K. Agarwal of Texas A&M University. We use a Latex-style for describing mathematical expressions.

Eq. (11): include a factor of c^2 in the first term on the RHS.

Eq. (25): the exponent of the term in square brackets should be 1/(\gamma - 1) .

Eq. (57): there should be a factor of 1/(\pi^2 \hbar^3) before the integral. Note that, in this section, we have set c = 1. Compare with Eqs. (10) and (13) for the electron Fermi gas case.

Eq. (58): in view of the correction in Eq. (57), it might have been more felicitous to have defined \epsilon_0 without the factor of 3 in the denominator. However, as we have emphasized, \epsilon_0 is an arbitrary dimensional constant.

Eq. (59): with \epsilon_0 defined as in Eq. (58), then there should be a factor of 3 before the integral.

Eq. (60): x_i should be written as k_F/m_n, not k_f/m_i.

Eq. (62): there should be a factor of 1/(3 \pi^2 \hbar^3) before the integral.

The errors Eq. (25) and in Eqs. (57-62) are only typos resulting from bad transcription of the Mathematica file to the LaTeX manuscript. The numerical value of \epsilon_0 in Eq. (29) and the masses in Table I are correct. Likewise, the fitted coefficients in Eq. (64) are correct and the concluding sentence of Section V is still valid.

Undergraduate students Irina Sagert and Matthias Hempel of the Goethe University, Frankfurt am Main, have also informed us of several errors, including some noted above by Agarwal. They find:

Eqs. (25), (57), (60), (62): as Agarwal, above.

Eq. (69): the factor of \hbar^2 in the second term on the RHS should not be there. (This equation is for an energy and we forgot that k_F is a momentum, not a wave number.)

Sec. VI-A, last paragraph: the relativistic gas has p = \epsilon/3, not \epsilon = p/3.

Eq. (86): it would be more consistent with our earlier use of "energy per particle" to have written this equation with each term divided by A.

After Eq. (82): text should read "For $n = n_0$ we note that $\langle E_F \rangle = \langle E^0_F \rangle$", i.e., the factor of 3/5 should be dropped. In view of this correction, the following two changes must be made.

Eq. (87): drop the factor of 3/5 before $\langle E^0_F \rangle$.

Eq. (89): the denominator before $\langle E^0_F \rangle$ is 3, not 5.