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We present the results of an optical spectroscopic campaign on the massive binary HD 152219 located near the core of the NGC 6231 cluster. Though the primary to secondary optical brightness ratio is probably about 10, we clearly detect the secondary spectral signature and we derive the first reliable SB2 orbital solution for the system. The orbital period is close to 4.2403 d and the orbit is slightly eccentric . The system is most probably formed by an O9.5 giant and a B1-2 V-III star. We derive minimal masses of and for the primary and secondary, respectively, and we constrain the stellar radius at values about 11 and . INTEGRAL-Optical Monitoring Camera (OMC) data reveal that HD 152219 is the third O-type eclipsing binary known in NGC 6231. In the Hertzsprung–Russell (HR) diagram, the primary component lies on the blue edge of the β Cep-type instability strip and its spectral lines display clear profile variations that are reminiscent of those expected from non-radial pulsations. Finally, we report the analysis of XMM–Newton observations of the system. The X-ray spectrum is relatively soft and is well reproduced by a two-temperature mekal model with and . The X-ray flux is most probably variable on a time-scale of days. The average X-ray luminosity during our campaign is , but shows fluctuations of about 10 per cent around this value. [ABSTRACT FROM AUTHOR]

Highlights: [•] This paper reports on the very first dedicated X-ray observation of the famous yellow hypergiant IRC+10420. [•] The target is not detected and upper limits on the X-ray flux are consistently derived and discussed. [•] The non-detection is interpreted in terms of high circumstellar absorption and likely weak intrinsic emission. [•] Other X-ray point sources in the field of view are briefly discussed. [ABSTRACT FROM AUTHOR]

Abstract: We present the results of an optical and X-ray monitoring campaign on the short-period massive SB2 binary HD 152218. Combining our HiRes spectroscopic data with previous observations, we unveil the contradictions between the published orbital solutions. In particular, we solve the aliasing on the period and derive a value close to 5.604d. Our eccentricity e =0.259±0.006 is slightly lower than previously admitted. We show that HD 152218 is probably undergoing a relatively rapid apsidal motion of about 3°yr−1 and we confirm the O9IV+O9.7V classification. We derive minimal masses of 15.82±0.26 M ⊙ and 12.00±0.19 M ⊙ and constrain the radius of the components to R 1 =10.3±1.3 R ⊙ and R 2 =7.8±1.7 R ⊙. We also report the results of an XMM-Newton monitoring of the HD 152218 X-ray emission throughout its orbital motion. The averaged X-ray spectrum is relatively soft and it is well reproduced by a 2-T optically thin thermal plasma model with component temperatures about 0.3 and 0.7keV. The system presents an increase of its X-ray flux by about 30% near apastron compared to periastron, which is interpreted as the signature of an ongoing wind–wind interaction process occurring within the wind acceleration region. [Copyright &y& Elsevier]