Search results for "Stars: Pulsars: General"

showing 3 items of 3 documents

Spin up and phase fluctuations in the timing of the accreting millisecond pulsar XTE J1807-294

2007

We performed a timing analysis of the 2003 outburst of the accreting X-ray millisecond pulsar XTE J1807-294 observed by RXTE. Using recently refined orbital parameters we report for the first time a precise estimate of the spin frequency and of the spin frequency derivative. The phase delays of the pulse profile show a strong erratic behavior superposed to what appears as a global spin-up trend. The erratic behavior of the pulse phases is strongly related to rapid variations of the light curve, making it very difficult to fit these phase delays with a simple law. As in previous cases, we have therefore analyzed separately the phase delays of the first harmonic and of the second harmonic of …

Orbital elementsPhysicsAstrophysics::High Energy Astrophysical PhenomenaAstrophysics (astro-ph)Phase (waves)Static timing analysisFOS: Physical sciencesAstronomy and AstrophysicsAstrophysicsLight curveAstrophysicsPulsars: General Stars: Pulsars: Individual: Alphanumeric: XTE J1807-294 Stars: Magnetic Fields Stars: Neutron X-Rays: Binaries [Stars]Pulse (physics)Settore FIS/05 - Astronomia E AstrofisicaSpace and Planetary ScienceMillisecond pulsarHarmonicStars: Pulsars: General Stars: Pulsars: Individual: Alphanumeric: XTE J1807-294 Stars: Magnetic Fields Stars: Neutron X-Rays: BinariesSpin-½
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BeppoSAX serendipitous discovery of the X-ray pulsar SAX J1802.7-2017

2003

We report on the serendipitous discovery of a new X-ray source, SAX J1802.7-2017, ~22' away from the bright X-ray source GX 9+1, during a BeppoSAX observation of the latter source on 2001 September 16-20. SAX J1802.7-2017 remained undetected in the first 50 ks of observation; the source count rate in the following ~300 ks ranged between 0.04 c/s and 0.28 c/s, corresponding to an averaged 0.1-10 keV flux of 3.6 10^{-11} ergs cm^{-2} s^{-1}. We performed a timing analysis and found that SAX J1802.7-2017 has a pulse period of 139.612 s, a projected semimajor axis of a_x sin i ~ 70 lt-s, an orbital period of ~4.6 days, and a mass function f(M) ~ 17 Msun. The new source is thus an accreting X-ra…

PhysicsSemi-major axisAstrophysics (astro-ph)FluxFOS: Physical sciencesAstronomy and AstrophysicsAstrophysicsAstrophysicsOrbital periodPulse periodSettore FIS/05 - Astronomia E AstrofisicaPulsarSpace and Planetary ScienceHigh massStars: Pulsars: General Stars: Pulsars: Individual: Alphanumeric: SAX J1802.7-2017 Stars: Magnetic Fields Stars: Neutron X-Rays: BinariesX-ray pulsar
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Order in the Chaos: Spin-up and Spin-down during the 2002 Outburst of SAX J1808.4-3658

2006

We present a timing analysis of the 2002 outburst of the accreting millisecond pulsar SAX J1808.4-3658. A study of the phase delays of the entire pulse profile shows a behavior that is surprising and difficult to interpret: superposed to a general trend, a big jump by about 0.2 in phase is visible, starting at day 14 after the beginning of the outburst. An analysis of the pulse profile indicates the presence of a significant first harmonic. Studying the fundamental and the first harmonic separately, we find that the phase delays of the first harmonic are more regular, with no sign of the jump observed in the fundamental. The fitting of the phase delays of the first harmonic with a model whi…

PhysicsAstrophysics::High Energy Astrophysical PhenomenaAstrophysics (astro-ph)Phase (waves)X-ray binaryFOS: Physical sciencesAstronomy and AstrophysicsAstrophysicsAstrophysicsPulse (physics)Neutron starPulsarSpace and Planetary ScienceMillisecond pulsarAstrophysics::Solar and Stellar AstrophysicsStars: Pulsars: General Stars: Pulsars: Individual: SAX J1808.4-3658 Stars: Magnetic Fields Stars: Neutron X-Rays: BinariesExponential decaySpin-½
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