Global X-Ray Properties of the O and B Stars In
                    Carina

Nazé, Yaël; Broos, P. S.; Oskinova, L. M.; Townsley, Leisa K.; Cohen, David H.; Corcoran, M. F.; Evans, Nancy Remage; Gagné, Marc; Moffat, A. F. J.; Pittard, J. M.; Rauw, Grégor; ud‐Doula, Asif; Walborn, N. R.

doi:10.1088/0067-0049/194/1/7

Cited by 124 publications

(179 citation statements)

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“…However, over recent years, large samples of massive stars with well-established multiplicity properties were studied using XMM-Newton and Chandra (e.g. Sana et al 2006b;Nazé 2009;Nazé et al 2011;Rauw et al 2015a) and revealed that not all massive binaries are indeed X-ray luminous. For instance, O-star binaries with orbital periods of a few days were found to be not particularly bright X-ray sources.…”

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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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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“…Early B stars mark the transition from strong winds / X-ray emitters to weak winds stars / X-ray dark stars toward the rise of coronal X-rays in late A and F type stars. The rate of detection in Xrays among B stars falls to about 50% (Wolk et al 2011;Nazé et al 2011;Berghoefer et al 1997). Little is known about windwind collision in binaries with B-type non-supergiant companions.…”

Section: Introductionmentioning

confidence: 98%

Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

Pillitteri¹,

Fossati²,

Castro³

et al. 2018

A&A

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Circumstantial evidence suggests that magnetism and enhanced X-ray emission are likely correlated in early B-type stars: similar fractions of them (∼ 10%) are strong and hard X-ray sources and possess strong magnetic fields. It is also known that some B-type stars have spots on their surface. Yet up to now no X-ray activity associated with spots on early-type stars was detected. In this Letter we report the detection of a magnetic field on the B2V star ρ Oph A. Previously, we assessed that the X-ray activity of this star is associated with a surface spot, herewith we establish its magnetic origin. We analyzed FORS2 ESO VLT spectra of ρ Oph A taken at two epochs and detected a longitudinal component of the magnetic field of order of ∼ 500 G in one of the datasets. The detection of the magnetic field only at one epoch can be explained by stellar rotation which is also invoked to explain observed periodic X-ray activity. From archival HARPS ESO VLT high resolution spectra we derived the fundamental stellar parameters of ρ Oph A and further constrained its age. We conclude that ρ Oph A provides strong evidence for the presence of active X-ray emitting regions on young magnetized early type stars.

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“…They are very bright, L X ∼ 10 31 -10 33 erg s −1 , but this X-ray emission only represents ∼ 10 −7 of their bolometric luminosity (Nazé et al 2011).…”

Section: X-ray Emission Processes For Ob Starsmentioning

confidence: 98%

X-rays from magnetic massive OB stars

Petit¹,

Cohen

Nazé

et al. 2013

Proc. IAU

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Abstract. The magnetic activity of solar-type and low-mass stars is a well known source of coronal X-ray emission. At the other end of the main sequence, X-rays emission is instead associated with the powerful, radiatively driven winds of massive stars. Indeed, the intrinsically unstable line-driving mechanism of OB star winds gives rise to shock-heated, soft emission (∼0.5 keV) distributed throughout the wind. Recently, the latest generation of spectropolarimetric instrumentation has uncovered a population of massive OB-stars hosting strong, organized magnetic fields. The magnetic characteristics of these stars are similar to the apparently fossil magnetic fields of the chemically peculiar ApBp stars. Magnetic channeling of these OB stars' strong winds leads to the formation of large-scale shock-heated magnetospheres, which can modify UV resonance lines, create complex distributions of cooled Halpha emitting material, and radiate hard (∼2-5 keV) X-rays. This presentation summarizes our coordinated observational and modelling efforts to characterize the manifestation of these magnetospheres in the X-ray domain, providing an important contrast between the emission originating in shocks associated with the large-scale fossil fields of massive stars, and the X-rays associated with the activity of complex, dynamo-generated fields in lower-mass stars.

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Global X-Ray Properties of the O and B Stars In Carina

Cited by 124 publications

References 50 publications

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

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

Detection of magnetic field in the B2 star ρ Ophiuchi A with ESO FORS2

X-rays from magnetic massive OB stars

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