Compositional Freeze-Out of Neutron Star Crusts

Details Compositional Freeze-Out of Neutron Star Crusts Compositional Freeze-Out of Neutron Star Crusts

2009-01-27

arxiv.org/abs/0901.4174v2

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

6 pages, 5 figures, accepted to MNRAS

Scientific paper

We have investigated the crustal properties of neutron stars without fallback accretion. We have calculated the chemical evolution of the neutron star crust in three different cases (a modified Urca process without the thermal influence of a crust, a thick crust, and a direct Urca process with a thin crust) in order to determine the detailed composition of the envelope and atmosphere as the nuclear reactions freeze out. Using a nuclear reaction network up to technetium, we calculate the distribution of nuclei at various depths of the neutron star. The nuclear reactions quench when the cooling timescale is shorter than the inverse of the reaction rate. Trace light elements among the calculated isotopes may have enough time to float to the surface before the layer crystallizes and form the atmosphere or envelope of the neutron star. The composition of the neutron-star envelope determines the total photon flux from the surface, and the composition of the atmosphere determines the emergent spectrum. Our calculations using each of the three cooling models indicate that without accretion of fallback the neutron star atmospheres are dependent on the assumed cooling process of the neutron star. Each of the cooling methods have different elements composing the atmosphere: for the modified Urca process the atmosphere is $^{28}$Si, the thick crust has an atmosphere of $^{50}$Cr, and the thin crust has an atmosphere of $^{40}$Ca. In all three cases the atmospheres are composed of elements which are lighter then iron.

Affiliated with

Also associated with

No associations

Rating

Compositional Freeze-Out of Neutron Star Crusts does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Compositional Freeze-Out of Neutron Star Crusts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compositional Freeze-Out of Neutron Star Crusts will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-361597