Line profile variability in the spectra of Oef stars

Becker, M. De; Rauw, Grégor

doi:10.1051/0004-6361:20040548

Cited by 15 publications

(22 citation statements)

References 35 publications

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“…However, such phenomena are expected to occur on time scales of a few hours (see e.g. Kambe et al, 1997;Rauw et al, 2008;De Becker et al, 2008), much shorter than the time scales reported above in the case of HD 195592. Non-radial pulsations may give rise to frequencies of a fraction of a day only if beating or resonance is occurring (Kaufer et al, 2006), but this is a priori unlikely to happen without the presence of parent peaks at much higher frequencies.…”

Section: Stellar Pulsationsmentioning

confidence: 79%

Spectroscopic study of the O-type runaway supergiant HD 195592

2010

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The scope of this paper is to perform a detailed spectroscopic study of the northern O-type supergiant HD 195592. We use a large sample of high quality spectra in order to investigate its multiplicity, and to probe the line profile variability. Our analysis reveals a clear spectroscopic binary signature in the profile of the He i λ 6678 line, pointing to a probable O + B system. We report on low amplitude radial velocity variations in every strong absorption line in the blue spectrum of HD 195592. These variations are ruled by two time-scales respectively of 5.063 and about 20 days. The former is firmly established, whilst the latter is poorly constrained. We report also on a very significant line profile variability of the H β line, with time scales strongly related to those of the radial velocities. Our results provide significant evidence that HD 195592 is a binary system, with a period that might be the variability time-scale of about 5 days. The second time scale may be the signature of an additional star moving along a wider orbit provided its mass is low enough, even though direct evidence for the presence of a third star is still lacking. Alternatively, the second time-scale may be the signature of a variability intrinsic to the stellar wind of the primary, potentially related to the stellar rotation.

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Section: Stellar Pulsationsmentioning

confidence: 79%

Spectroscopic study of the O-type runaway supergiant HD 195592

2010

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“…If HIP 99580 is a BSS runaway star, it should show signs of stellar evolution in the former system such as a large rotational velocity and an enhanced helium abundance caused by momentum and mass transfer during evolution. It was claimed by Barannikov (1993) that HIP 99580 is a spectroscopic binary, however De Becker & Rauw (2004) 14 and Turner et al (2008) could not confirm this. According to Conti & Ebbets (1977), the O5 type star HIP 99580 is a rapid rotator with v sin i = 270 km s −1 .…”

Section: The Origin Of Psr B2224+65mentioning

confidence: 93%

XMM-NEWTONOBSERVATION OF PSR B2224+65 AND ITS JET

Hui

Huang

Trepl

et al. 2012

ApJ

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We have investigated the pulsar PSR B2224+65 and its X-ray jet with XMM-Newton. Apart from the long X-ray jet which is almost perpendicular to the direction of proper motion, a putative extended feature at the pulsar position, which oriented in the opposite direction of the proper motion, is also suggested by this deep X-ray imaging. Non-detection of any coherent X-ray pulsation disfavors the magnetospheric origin of the X-rays observed from the position of PSR B2224+65 and hence suggest that the interpretation of pulsar wind nebula is more viable. We have also probed the origin of PSR B2224+65 and identified a runaway star, which possibly originated from the Cygnus OB9 assoication, as a candidate for the former binary companion of the neutron star's progenitor.

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“…The behaviour remains coherent but only for a while during the lifetime of the spot, and as new spots arise, a phase shift and a change in the light curve shape can be observed. In any case, this somewhat erratic behaviour is usual for Oef stars such as ζ Pup, where cycles with similar but not perfectly identical periodicities are often found in spectroscopic time series (Rauw et al 2003(Rauw et al , 2015De Becker & Rauw 2004;Sudnik & Henrichs 2016). However, at a given date, the star should display one single behaviour.…”

Section: Shapes Of the Variationsmentioning

confidence: 94%

A detailed X-ray investigation of ζ Puppis

Nazé

Ramiaramanantsoa

Stevens

et al. 2018

A&A

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Context. One of the optically brightest and closest massive stars, ζ Pup, is also a bright X-ray source. Previously, its X-ray emission was found to be variable with light curves harbouring “trends” with a typical timescale longer than the exposure length, i.e. >1 d. The origin of these changes was proposed to be linked to large-scale structures in the wind of ζ Pup, but further characterization of the variability at high energies was needed to investigate this scenario. Aims. Since the previous papers of this series, a number of new X-ray observations have become available. Furthermore, a cyclic behaviour with a 1.78 d period was identified in long optical photometric runs, which is thought to be associated with the launching mechanism of large-scale wind structures. Methods. We analysed these new X-ray data, revisited the old data, and compared the X-ray light curves with the optical data, notably those taken simultaneously. Results. The behaviour of ζ Pup in X-rays cannot be explained in terms of a perfect clock because the amplitude and shape of its variations change with time. For example, ζ Pup was much more strongly variable between 2007 and 2011 than before and after this interval. Comparing the X-ray spectra of the star at maximum and minimum brightness yields no compelling difference beyond the overall flux change: the temperatures, absorptions, and line shapes seem to remain constant, well within errors. The only common feature between X-ray datasets is that the variation amplitudes appear maximum in the medium (0.6–1.2 keV) energy band. Finally, no clear and coherent correlation can be found between simultaneous X-ray and optical data. Only a subgroup of observations may be combined coherently with the optical period of 1.78 d, although the simultaneous optical behaviour is unknown. Conclusions. The currently available data do not reveal any obvious, permanent, and direct correlation between X-ray and optical variations. The origin of the X-ray variability therefore still needs to be ascertained, highlighting the need for long-term monitoring in multiwavelengths, i.e. X-ray, UV, and optical.

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Line profile variability in the spectra of Oef stars

Cited by 15 publications

References 35 publications

Spectroscopic study of the O-type runaway supergiant HD 195592

Spectroscopic study of the O-type runaway supergiant HD 195592

XMM-NEWTONOBSERVATION OF PSR B2224+65 AND ITS JET

A detailed X-ray investigation of ζ Puppis

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