Astron. Astrophys. 344, 151-153 (1999)

On the minimum period of uniformly rotating neutron stars

P. Haensel ^1,2, J.P. Lasota ¹ and J.L. Zdunik <sup>2

1</sup> Departement d'Astrophysique Relativiste et de Cosmologie, UPR 176 du CNRS, Observatoire de Paris, Section de Meudon, F-92195 Meudon Cedex, France
² N. Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, PL-00-716 Warszawa, Poland (jlz@camk.edu.pl; haensel@camk.edu.pl; lasota@obspm.fr)

Received 9 November 1998 / Accepted 8 January 1999

Abstract

We show that the neutron star minimum period of uniform rotation is determined, for causal equations of state, by the maximum value of the relativistic (compactness) parameter , allowed by causality for static neutron stars, 0.7081, and by the largest measured mass of a neutron star. The relation between these three quantities, resulting from the extrapolation of the empirical formulae of Lasota et al. (1996), yields the minimum period of 0.288 ms, only 2% higher than an absolute lower bound obtained in extensive exact numerical calculations of Koranda et al. (1997).

Key words: dense matter stars: neutron stars: pulsars: general

Present address: Institut d'Astrophysique de Paris, CNRS, 98bis Boulevard Arago, F-75014 Paris, France

Send offprint requests to: P. Haensel

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Contents

• 1. Introduction
• 2. Relation between x_s and P_min
• 3. Lower bound on P_min
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 10, 1999
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