Sudden Radiative Braking in Colliding Hot‐Star Winds

Gayley, K. G.; Owocki, S. P.; Cranmer, Steven R.

doi:10.1086/303573

Cited by 167 publications

(208 citation statements)

References 36 publications

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“…4. For the O+OB binaries with spectral information and defined period, log f X / f BOL ratio from Table 6. inhibition, where the radiation of one component decelerates the wind originating in its companion (Gayley et al 1997;Antokhin et al 2004). It should have more impact on short-period systems than on long-period binaries.…”

Section: Summary and Discussion: The X-ray Properties Of Ob Starsmentioning

confidence: 99%

Hot stars observed by XMM-Newton

Nazé¹

2009

A&A

139

164

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Aims. Following the advent of increasingly sensitive X-ray observatories, deep observations of early-type stars became possible. However, the results for only a few objects or clusters have until now been reported and there has been no large survey comparable to that based upon the ROSAT All-Sky Survey (RASS). Methods. A limited survey of X-ray sources, consisting of all public XMM-Newton observations (2XMMi) and slew survey data (XMMSL1), is now available. The X-ray counterparts to hot, massive stars have been searched for in these catalogs. Results. About 300 OB stars were detected with XMM-Newton. Half of them were bright enough for a spectral analysis to be possible, and we make available the detailed spectral properties that were derived. The X-ray spectra of O stars are represented well by low (<1 keV) temperature components and seem to indicate that an absorption column is present in addition to the interstellar contribution. The X-ray fluxes are well correlated with the bolometric fluxes, with a scatter comparable to that of the RASS studies and thus larger than found previously with XMM-Newton for some individual clusters. These results contrast with those of B stars that exhibit a large scatter in the L X − L BOL relation, no additional absorption being found, and the fits indicate a plasma at higher temperatures. Variability (either within one exposure or between multiple exposures) was also investigated whenever possible: short-term variations are far more rare than long-term ones (the former affects a few percent of the sample, while the latter concerns between one third and two thirds of the sources).Conclusions. This paper presents the results of the first high-sensitivity investigation of the overall high-energy properties of a sizable sample of hot stars.

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Section: Summary and Discussion: The X-ray Properties Of Ob Starsmentioning

confidence: 99%

Hot stars observed by XMM-Newton

Nazé¹

2009

A&A

139

164

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“…In this type of wind interaction, the secondary's luminosity slows down the primary's wind before it encounters the shock wave (Gayley et al 1997), substantially reducing the X-ray intensity and making it softer (Usov 1992). The slowing down process by the secondary radiation pressure affects the location of the new stagnation point, but does not push it back to its original place.…”

Section: Discussion and Summarymentioning

confidence: 99%

Accretion by the Secondary in η Carinae During the Spectroscopic Event. I. Flow Parameters

Soker

2005

ApJ

120

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We examine the influence of the gravity of the companion (the secondary) to the massive primary star Carinae on the winds blown by the primary and the secondary. The two winds collide with each other after passing through two respective shock waves, and escape the system while strongly emitting in the X-ray band. While during most of the 5.5 yr orbital period the companion's gravity has a negligible effect on the winds, we find that near periastron the companion's gravity may significantly influence the flow, and the companion might accrete from the primary's wind under certain circumstances. Near periastron passage, the collision region of the two winds may collapse onto the secondary star, a process that could substantially reduce the X-ray luminosity. We suggest that such an accretion process produces the long, almost flat, X-ray minimum in Car.

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“…For instance, O-star binaries with orbital periods of a few days were found to be not particularly bright X-ray sources. This might be due to radiative braking (Gayley et al 1997) and/or radiative inhibition (Stevens & Pollock 1994) that lower the pre-shock wind velocities (e.g. Pittard 2009, and references therein).…”

Section: Postdoctoral Researcher Frs-fnrs (Belgium) Senior Research mentioning

confidence: 99%

Testing the theory of colliding winds: the periastron passage of 9 Sagittarii

Rauw

Blomme

Nazé

et al. 2016

A&A

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Context. The long-period, highly eccentric O-star binary 9 Sgr, known for its non-thermal radio emission and its relatively bright X-ray emission, went through its periastron in 2013. Aims. Such an event can be used to observationally test the predictions of the theory of colliding stellar winds over a broad range of wavelengths. Methods. We conducted a multi-wavelength monitoring campaign of 9 Sgr around the 2013 periastron. In this paper, we focus on X-ray observations and optical spectroscopy. Results. The optical spectra allow us to revisit the orbital solution of 9 Sgr and to refine its orbital period to 9.1 years. The X-ray flux is maximum at periastron over all energy bands, but with clear differences as a function of energy. The largest variations are observed at energies above 2 keV, whilst the spectrum in the soft band (0.5−1.0 keV) remains mostly unchanged, indicating that it arises far from the collision region, in the inner winds of the individual components. The level of the hard emission at periastron clearly deviates from the 1/r relation expected for an adiabatic wind-interaction zone, whilst this relation seems to hold at the other phases that are covered by our observations. The spectra taken at phase 0.946 reveal a clear Fe xxv line at 6.7 keV, but no such line is detected at periastron (φ = 0.000), although a simple model predicts a strong line that should be easily visible in the data. Conclusions. The peculiarities of the X-ray spectrum of 9 Sgr could reflect the effect of radiative inhibition as well as a phasedependent efficiency of particle acceleration on the shock properties.

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Sudden Radiative Braking in Colliding Hot‐Star Winds

Cited by 167 publications

References 36 publications

Hot stars observed by XMM-Newton

Hot stars observed by XMM-Newton

Accretion by the Secondary in η Carinae During the Spectroscopic Event. I. Flow Parameters

Testing the theory of colliding winds: the periastron passage of 9 Sagittarii

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