Issue |
A&A
Volume 385, Number 1, April I 2002
|
|
---|---|---|
Page(s) | 301 - 307 | |
Section | Astronomical instrumentation | |
DOI | https://doi.org/10.1051/0004-6361:20020131 | |
Published online | 15 April 2002 |
Equation of state of dense matter and the minimum mass of cold neutron stars
1
N. Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warszawa, Poland e-mail: jlz@camk.edu.pl
2
Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
3
Centre de Recherche Astronomique de Lyon, ENS de Lyon, 69364 Lyon, France
Corresponding author: P. Haensel, haensel@camk.edu.pl
Received:
30
July
2001
Accepted:
9
January
2002
Equilibrium configurations of cold neutron stars
near the minimum mass
are studied, using the recent equation of state SLy, which describes
in a unified, physically consistent manner, both the solid crust and
the liquid core of neutron stars. Results are compared with those
obtained using an older FPS equation of state of cold catalyzed matter.
The value of depends very
weakly on the equation of state of cold catalyzed matter: it is
for the SLy model, and
for the FPS one. Central density at Mmin is
significantly lower than
the normal nuclear density: for the SLy
equation of state we get central density
, to be
compared with
obtained for the FPS
one. Even at Mmin, neutron stars have a small liquid
core of radius of about 4 km,
containing some 2–3% of the stellar mass. Neutron stars
with
are bound with respect to dispersed
configuration of the hydrogen gas, but are unbound with respect to
dispersed
.
The effect of uniform rotation on the minimum-mass configuration of cold
neutron stars is studied. Rotation increases the value of Mmin;
at rotation period of 10 ms the minimum mass of neutron stars
increases to
, and
corresponds to the mass-shedding
(Keplerian) configuration. In the case of the shortest observed
rotation period of radio pulsars 1.56 ms, minimum mass of
uniformly rotating cold neutron stars corresponds to the mass-shedding
limit, and is found at
for the SLy EOS and
for the FPS EOS.
Key words: dense matter / equation of state / stars: neutron / stars: general
© ESO, 2002
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