2008ApJ...679.1433F -
Astrophys. J., 679, 1433-1442 (2008/June-1)
A massive neutron star in the globular cluster M5.
FREIRE P.C.C., WOLSZCZAN A., VAN DEN BERG M. and HESSELS J.W.T.
Abstract (from CDS):
We report the results of 19 years of Arecibo timing for two pulsars in the globular cluster NGC 5904 (M5), PSR B1516+02A (M5A) and PSR B1516+02B (M5B). This has resulted in the measurement of the proper motions of these pulsars and, by extension, that of the cluster itself. M5B is a 7.95 ms pulsar in a binary system with a >0.13 M☉ companion and an orbital period of 6.86 days. In deep HST images, no optical counterpart is detected within ∼2.5 σ of the position of the pulsar, implying that the companion is either a white dwarf or a low-mass main-sequence star. The eccentricity of the orbit (e=0.14) has allowed a measurement of the rate of advance of periastron: ω{dot}=0.0142°±0.0007°/yr. We argue that it is very likely that this periastron advance is due to the effects of general relativity, the total mass of the binary system then being 2.29±0.17 M☉. The small measured mass function implies, in a statistical sense, that a very large fraction of this total mass is contained in the pulsar: Mp=2.08±0.19 M☉(1 σ); there is a 5% probability that the mass of this object is <1.72 M☉ and a 0.77% probability that 1.2 M☉≤Mp≤1.44 M☉. Confirmation of the median mass for this neutron star would exclude most ``soft'' equations of state for dense neutron matter. Millisecond pulsars (MSPs) appear to have a much wider mass distribution than is found in double neutron star systems; about half of these objects are significantly more massive than 1.44 M☉. A possible cause is the much longer episode of mass accretion necessary to recycle a MSP, which in some cases corresponds to a much larger mass transfer.
Abstract Copyright:
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Journal keyword(s):
Stars: Binaries: General - Equation of State - Stars: Pulsars: General - Stars: Pulsars: Individual: Alphanumeric: PSR B1516+02A - Stars: Pulsars: Individual: Alphanumeric: PSR B1516+02B - Stars: Neutron
Nomenclature:
Fig.3: [FWV2008] Star N (Nos 1-2).
Simbad objects:
24
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