The X-ray properties of 3A1907 + 09

Cook, Mike; Page, C. G.

doi:10.1093/mnras/225.2.381

Cited by 26 publications

(30 citation statements)

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“…1), which is very similar to those observed with T enma (Makishima et al 1984) and EXOSAT (Cook & Page 1987) in its "" Ñaring ÏÏ states. However as shown in Figure 1, we encountered peculiar occasions, unrelated to any terrestrial phenomena such as Earth occultations, when the pulsation nearly disappeared but there still remained signiÐcant source Ñux of order 3 mcrab.…”

Section: U 1907]09supporting

confidence: 87%

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Cyclotron Resonance Effects in Two Binary X‐Ray Pulsars and the Evolution of Neutron Star Magnetic Fields

Makishima

Mihara

Nagase

et al. 1999

ApJ

189

222

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The Ginga X-ray spectra of the two binary X-ray pulsars, 4U 1907]09 and Vela X-1, were analyzed for e †ects due to electron cyclotron resonance. For this purpose, a new continuum spectral model, called NPEX, was developed. The NPEX model, combined with the classical cyclotron scattering line proÐle, was Ðrst tested against the Ginga spectra (typically in 2È50 keV) of Her X-1, 4U 0115]63, 4U 1538[52, X0331]53, and Cep X-4 and was conÐrmed to reproduce successfully their overall spectra including the previously known cyclotron resonance features. Through application of the same model to the pulsephaseÈaveraged and phase-resolved Ginga spectra, it was conÐrmed that 4U 1907]09 and Vela X-1 exhibit fundamental cyclotron resonances at D20 and D25 keV, respectively. The data for both objects are also consistent with the presence of the second-harmonic resonances, which were discovered with hard X-ray experiments. Including these two examples, the cyclotron resonance e †ects are now established in about a dozen binary X-ray pulsars. Their surface magnetic Ðeld strengths, implied by their resonance energies, apparently distribute over a narrow range of (1È4) ] 1012 G. Although the fewer number of higher Ðeld objects may be an instrumental selection e †ect, the lack of objects with magnetic Ðelds of (0.2È1) ] 1012 G is concluded to be real. A limited number of ASCA data are utilized to reinforce this conclusion. These results suggest that the magnetic Ðeld of binary X-ray pulsars do not decay signiÐcantly at least in D108 yr.

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Section: U 1907]09supporting

confidence: 87%

“…The noneclipsing binary pulsar 4U 1907]09 has an orbital period of 8.38 days (Marshall & Ricketts 1980) and a pulse period of 438 s (Makishima et al 1984 ;Cook & Page 1987). Its optical companion is a highly reddened massive star (Iye 1986).…”

Section: U 1907]09mentioning

confidence: 99%

Cyclotron Resonance Effects in Two Binary X‐Ray Pulsars and the Evolution of Neutron Star Magnetic Fields

Makishima

Mihara

Nagase

et al. 1999

ApJ

189

222

View full text Add to dashboard Cite

show abstract

“…The presence of X-ray flaring seen twice per neutron star orbit (Marshall & Ricketts 1980) had led some authors (e.g. Makishima et al 1984;Cook & Page 1987;Iye 1986) to the hypothesis of a Be star companion. However, this classification would require a distance of <1.5 kpc, which is in contradiction to the significant interstellar extinction measured in optical observations by van Kerkwijk et al (1989), who also classified the counterpart as a B supergiant.…”

Section: U 1907+09mentioning

confidence: 99%

“…The spectrum is modified by strong photoelectric absorption with a column density N H = 1.5-5.7 × 10 22 cm −2 (e.g. Cook & Page 1987).…”

Section: U 1907+09mentioning

confidence: 99%

Unveiling the nature of six HMXBs through IR spectroscopy

Nespoli¹,

Fabregat²,

Mennickent

2008

A&A

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Context. The International Gamma-Ray Astrophyiscs Laboratory (INTEGRAL) is discovering a large number of new hard X-ray sources, many of them being HMXBs. The identification and spectral characterization of their optical/infrared counterparts is a necessary step to undertake detailed study of these systems. In particular, the determination of the spectral type is crucial in the case of the new class of Supergiant Fast X-ray Transients (SFXTs), which show X-ray properties common to other objects. Aims. Our goal is to perform spectral analysis and classification of proposed counterparts to HMXBs in order to characterize the system they belong to. Methods. We used the ESO/NTT SofI spectrograph to observe proposed IR counterparts to HMXBs, obtaining K s medium resolution spectra (R = 1320) with a S /N 100. We classified them through comparison with published atlases. Results. We were able to spectrally classify the six sources. This allowed us to ascribe one of them to the new class of SFXTs and confirm the membership of two sources to this class. We confirmed the spectral classification, derived from optical spectroscopy, of a known system, 4U 1907-09, showing for the first time its infrared spectrum. The spectral classification was also used to estimate the distance of the sources. We compared the extinction as derived from X-ray data with effective interstellar extinction obtained from our data, discussing the absorption component due to the circumstellar environment, which we observed in four systems; in particular, intrinsic absorption seems to emerge as a typical feature of the entire class of SFXTs.

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“…Subsequent pulse-timing analyses with EXOSAT (Cook & Page 1987) and, more recently, with the Rossi X-ray Timing Based on observations made at the European Southern Observatory, Paranal, Chile (ESO program 67.C-0281).…”

Section: Introductionmentioning

confidence: 99%

VLT/UVES spectroscopy of the O supergiant companion to 4U 1907+09(7)

Cox¹,

Kaper²,

Mokiem³

2005

A&A

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Abstract. High-resolution optical spectra of the high-mass X-ray binary 4U 1907+09 covering the wavelength range 4680−10 400 Å indicate that the X-ray pulsar's massive companion is an O8/O9 supergiant with a dense stellar wind. The interstellar atomic lines of Na  and K  of this strongly reddened source (E (B−V) = 3.45 mag) are used to set a lower limit to its distance: d ≈ 5 kpc, excluding the possibility that the massive companion is a Be star. We re-evaluate the system parameters; the new spectral classification of 4U 1907+09's O supergiant companion is discussed in the context of its similarity in X-ray and orbital properties to Wray 15-977/GX 301-2. The Hα line shows variability similar to what is observed in other wind-fed systems. A remarkable feature is the strong He  4686 Å emission line, which possibly originates in the accretion flow towards the X-ray pulsar.

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The X-ray properties of 3A1907 + 09

Cited by 26 publications

References 0 publications

Cyclotron Resonance Effects in Two Binary X‐Ray Pulsars and the Evolution of Neutron Star Magnetic Fields

Cyclotron Resonance Effects in Two Binary X‐Ray Pulsars and the Evolution of Neutron Star Magnetic Fields

Unveiling the nature of six HMXBs through IR spectroscopy

VLT/UVES spectroscopy of the O supergiant companion to 4U 1907+09(7)

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