Discovery of 9.3 S X-ray pulsations from 2S 1553-542 and a determination of the orbit

Kelley, R. L.; Rappaport, S.; Ayasli, S.

doi:10.1086/161488

Cited by 37 publications

(29 citation statements)

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“…(2007); 16 Staubert et al. (2011); 17 Raichur & Paul (2010b); 18 in’t Zand, Corbet & Marshall (2001); 19 Kelley, Rappaport & Ayasli (1983); 20 Baykal et al. (2010); 21 Scott et al.…”

Section: Discussionmentioning

confidence: 99%

On the orbital parameters of Be/X-ray binaries in the Small Magellanic Cloud

Townsend¹,

Coe²,

Corbet³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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The orbital motion of a neutron star about its optical companion presents a window through which we can study the orbital parameters of that binary system. This has been used extensively in the Milky Way to calculate these parameters for several high‐mass X‐ray binaries. Using several years of Rossi X‐ray Timing Explorer Proportional Counter Array data, we derive the orbital parameters of four Be/X‐ray binary systems in the Small Magellanic Cloud (SMC), increasing the number of systems with orbital solutions by a factor of 3. We find one new orbital period, confirm a second and discuss the parameters with comparison to the Galactic systems. Despite the low metallicity in the SMC, these binary systems sit amongst the Galactic distribution of orbital periods and eccentricities, suggesting that metallicity may not play an important role in the evolution of high‐mass X‐ray binary systems. A plot of orbital period against eccentricity shows that the supergiant, Be and low‐eccentricity OB transient systems occupy separate regions of the parameter space; akin to the separated regions on the Corbet diagram. Using a Spearman’s rank correlation test, we also find a possible correlation between the two parameters. The mass functions, inclinations and orbital semimajor axes are derived for the SMC systems based on the binary parameters and the spectral classification of the optical counterpart. As a by‐product of our work, we present a catalogue of the orbital parameters for every high‐mass X‐ray binary in the Galaxy and Magellanic Clouds for which they are known.

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“…(2007); 16 Staubert et al. (2011); 17 Raichur & Paul (2010b); 18 in’t Zand, Corbet & Marshall (2001); 19 Kelley, Rappaport & Ayasli (1983); 20 Baykal et al. (2010); 21 Scott et al.…”

Section: Discussionmentioning

confidence: 99%

On the orbital parameters of Be/X-ray binaries in the Small Magellanic Cloud

Townsend¹,

Coe²,

Corbet³

et al. 2011

Monthly Notices of the Royal Astronomical Society

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“…The transient X‐ray source 2S 1553−542 was discovered at the time of outburst in observations using the rotation modulation collimator onboard Small Astronomy Satellite 3 in 1975 June (Apparao et al 1978 and reference therein) as a part of a systematic survey of the Galactic plane. Later, from the detailed analysis of the same data, Kelley, Rappaport & Ayasli (1983) found that the source is a transient X‐ray pulsar with the period of 9.3 s. They also found large variation in the spin period. Analysing different timing properties of the source and finding similar properties with the Be/X‐ray binary pulsar 4U 0115+63 (Rappaport et al 1978), they concluded that the X‐ray pulsar is probably in a binary orbit with a Be‐type companion star where the binary orbital period is 30.6 ± 2.2 d and the X‐ray mass function is 5.0 ± 2.1 M ⊙ .…”

Section: Introductionmentioning

confidence: 92%

RXTE observation of recent flaring activity from the transient X-ray pulsar 2S 1553−542

Pahari

Pal

2012

Monthly Notices of the Royal Astronomical Society

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We summarize the analysis of observations made by the Rossi X‐ray Timing Explorer and the Swift/Burst Alert Telescope at the time of the recent flaring activity of the transient X‐ray pulsar 2S 1553−542. The binary system is characterized by the projected semimajor axis ax sin i of 168 ± 18 light‐seconds, the binary orbital period Porb of 29.56 ± 0.53 d and the X‐ray mass function fx(M) of 5.3 ± 1.2 M⊙. We also found Pspin= 9.2829 ± 0.0003 s with s s−1, i.e. a spin‐up rate of yr−1. The spin period is found to decrease more slowly than that of most other X‐ray pulsars. As the flare decays with time, the structure and X‐ray counts in the pulse profile showed considerable variability. However, no significant structural variability is seen in single‐peaked pulse profiles in different energy bands. Pulsed fraction decreases with the decay of the flare but its value at different energy bands showed a discontinuity. Using X‐ray spectroscopy at different orbital cycles, we have detected the presence of the Fe Kα emission line in the spectra with a minimum significance of 3σ. Apart from a consistent increase in blackbody temperature, other spectral parameters are found to be stable throughout orbital cycles. From detailed spectral and timing analysis, we concluded that the X‐ray flare is spectrally hard and we confirmed the nature of the compact object as a transient, accretion‐powered, spin‐up X‐ray pulsar with a Be‐type companion.

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“…Even now, however, the orbit of 8MC X-I is the most precisely determined binary stellar orbit in an extragalactic system. All the measured orbits of binary X-ray pulsars [with the exceptions of 4UI626-67, which is discussed in Section 2.3.2, and the newly discovered pulsar 28 1553 -54 (Kelley et al 1983c)] are shown to scale in Figure 8, in order of increasing size of the semimajor axis (see also Table 1) . Nominal values for the masses and radii of the companion stars are indicated in the figure; the derivation of these param e ters is described below.…”

Section: Orbital Determinations and The Evaluation Of Binarymentioning

confidence: 99%