Lower mass limit for neutron stars?

1. Jul 30, 2011

Reedbeta

I was wondering, does anyone know of a lower limit on the mass of a neutron star from fundamental physics? That is, the smallest it could be before its pressure would make it explode.

I don't mean the Chandrasekhar limit, as that's the upper limit for a white dwarf. Neutron stars occurring "in the wild" probably can't be too much smaller than this, as they would never have collapsed to a neutron star in the first place, but ignoring that fact, might much-smaller neutron stars be stable if they could somehow be created?

2. Jul 30, 2011

SteamKing

Staff Emeritus
The funny thing about neutron stars is they don't explode. If a neutron star accretes enough mass after formation, it will collapse into a black hole.

3. Jul 30, 2011

bcrowell

Staff Emeritus
I think the Chandrasekhar limit is the limit. The Chandrasekhar limit isn't based on stellar evolution or detailed mechanisms of collapse. It's based on stability. If you could initially form a ball of neutrons with a mass under the Chandrasekhar limit, I think it would do $n\rightarrow p+e^-+\bar{\nu}$ and turn into a white dwarf.

4. Jul 30, 2011

marcus

Intriguing thought! I suspect you are right. Nothing else seems to make sense.

5. Jul 31, 2011

Chronos

See http://arxiv.org/abs/astro-ph/0012321
On the minimum and maximum mass of neutron stars and the delayed collapse
Authors: Klaus Strobel, Manfred K. Weigel (University of Munich)
(Submitted on 14 Dec 2000)
Abstract: The minimum and maximum mass of protoneutron stars and neutron stars are investigated. The hot dense matter is described by relativistic (including hyperons) and non-relativistic equations of state. We show that the minimum mass ($\sim$ 0.88 - 1.28 $M_{\sun}$) of a neutron star is determined by the earliest stage of its evolution and is nearly unaffected by the presence of hyperons. The maximum mass of a neutron star is limited by the protoneutron star or hot neutron star stage. Further we find that the delayed collapse of a neutron star into a black hole during deleptonization is not only possible for equations of state with softening components, as for instance, hyperons, meson condensates etc., but also for neutron stars with a pure nucleonic-leptonic equation of state.
Comments: 6 pages, 4 figures, using EDP Siences Latex A&A style, to be published in A&A
Subjects: Astrophysics (astro-ph); Nuclear Theory (nucl-th)
Journal reference: Astron.Astrophys.367:582,2001
DOI: 10.1051/0004-6361:20000428
Cite as: arXiv:astro-ph/0012321v1

6. Aug 3, 2011

Chronos

The key factor is the core mass of the progenitor star. The supernova event that births a neutron star expels a large fraction of the progenitor star mass. Most known neutron stars fall below the Chandrasekhar mass limit. The lowest known neutron star mass is around 1 solar.

Last edited: Aug 3, 2011