The optical counterpart to the Be/X-ray binary SAX J2239.3+6116

Reig, P.; Blay, P.; Blinov, D.

doi:10.1051/0004-6361/201629603

Cited by 8 publications

(5 citation statements)

References 56 publications

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“…The optical counterpart is a V = 14.8 B0Ve star located at a distance of ∼4.9 kpc (in't Zand et al 2000). The long-term optical variability is characterized by the slow dissipation of the circumstellar disk around the Be star companion (Reig et al 2017). SAX J2239.3+6116 was observed during four contiguous nights from the Skinakas observatory on 22-25 August 2011 and20-23 August 2019 (Table D.3).…”

Section: Cep X-4mentioning

confidence: 99%

“…To investigate whether the nature of the BeXB variability is similar or not to that of classical Be stars, we compared our results of the previous sections with those obtained by Labadie- Bartz et al (2022) for a larger sample of Be stars observed by TESS during the first year of the mission. In this comparison, we take into account that the spectral type distribution in BeXB lies in the narrow range O9-B2, with a peak around B0 (Negueruela 1998;Reig et al 2017), and hence we compare our results with those of the early group (B3 and earlier) defined by Labadie- Bartz et al (2022).…”

Section: Comparison With B and Classical Be Starsmentioning

confidence: 99%

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Fast time optical variability in Be/X-ray binaries

Reig

Fabregat

2022

A&A

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Context. Classical Be stars, regardless of spectral subtype, display multiperiodic light modulations in the frequency range 0.1-12 c d −1 , when observed with high-cadence and long duration. This behaviour is attributed to non-radial pulsations and/or rotation of the Be star. A similar study for the optical counterparts to Be/X-ray binaries is yet to be carried out. Aims. The main goal of this work is to investigate the fast photometric variability of the optical counterparts to Be/X-ray binaries and compare the general patterns of such variability with the Galactic population of classical Be stars. Methods. The main core of our analysis is based on space-based observations performed by TESS. We analyzed 21 sources with TESS. High-cadence photometry with two ground-based telescopes was also performed for 15 sources. The TESS light curves were created from the full-frame images using the Lightkurve package. The ground-based light curves were obtained through differential photometry between the target and a number of non-variable stars in the same field of view. Standard Fourier analysis and least-squares fitting methods were employed in the frequency analysis. Results. All sources exhibit intra-night light variations with intensity variations of 0.01-0.06 mag in the ground-based observations and up to 5% in flux in TESS observations. This variability manifests itself as multi-periodic signals in the frequency range 0.2-12 c d −1 . We find that the patterns of variability of the Be stars in Be/X-ray binaries agree with that of classical early-type Be stars in terms of the general shape of the periodograms. Based on the general shape and number of peaks in the periodograms, Be/X-ray binaries can be classified into different types. The most common case is the presence of groups of closely-spaced frequencies (67)%, followed by sources that exhibit isolated signals (18%). The remaining type of sources displays frequency spectra characterized by a mixed pattern of stochastic variability and high-frequency peaks. Conclusions. This study reveals that short-term optical photometric variability is a very common, if not ubiquitous, feature intrinsic to the Be optical companions in Be/X-ray binaries. This variability is mainly attributed to pulsations that originate in the stellar interior.

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Section: Cep X-4mentioning

confidence: 99%

Section: Comparison With B and Classical Be Starsmentioning

confidence: 99%

Fast time optical variability in Be/X-ray binaries

Reig

Fabregat

2022

A&A

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“…Some papers greatly facilitated the process as they already listed information on some HMXBs in our catalogue. Orbital periods, spin periods, and spectral types are found in Belczynski & Ziolkowski (2009), spin periods of pulsars are reported in Annala & Poutanen (2010), spectroscopic information on Ae/Be stars is given in Fairlamb et al (2015), tabled data on BeHMXBs is presented in Tsygankov et al (2017) and Reig et al (2017), HMXBs detected by INTEGRAL are reported in , an overview of SFXT candidates is given in Sguera et al (2020), much information on radio pulsars is collected in van den Eijnden et al ( 2021), XMM-Newton and Swift A&A proofs: manuscript no. aa45236 observations of sgHMXBs are reported in Ferrigno et al (2022), and HMXBs seen by Fermi are presented in Harvey et al (2022).…”

Section: Retrieving Binary Parameters and New Hmxbsmentioning

confidence: 99%

A catalogue of high-mass X-ray binaries in the Galaxy: from the INTEGRAL to theGaiaera

Fortin

García

Simaz-Bunzel

et al. 2023

A&A

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Context. High-mass X-ray binaries (HMXBs) are a particular class of high-energy sources that require multi-wavelength observational efforts to be properly characterised. New identifications and the refinement of previous measurements are regularly published in the literature by independent teams of researchers and might, when they are collected in a catalogue, offer a tool for facilitating further studies of HMXBs. Aims. We update previous instances of HMXB catalogues in the Galaxy and provide the community easy access to the most complete set of observables on Galactic HMXBs. In addition to the fixed version that is available in Vizier, we also aim to host and maintain a dynamic version that can be updated upon request from users. Any modification will be logged in this version. Methods. Using previous HMXB catalogues supplemented by listings of hard X-ray sources detected in the past 20 years, we produced a base set of HMXBs and candidates by means of identifier and sky coordinate cross matches. We queried in Simbad for unreferenced HMXBs. We searched for as many hard X-ray, soft X-ray, optical, and infrared counterparts to the HMXBs as we could in well-known catalogues and compiled their coordinates. Each HMXB was subjected to a meticulous search in the literature to find relevant measurements and the original reference. Results. We provide a catalogue of 152 HMXBs in the Galaxy with their best known coordinates, the spectral type of the companion star, systemic radial velocities, component masses, orbital period, eccentricity, and spin period when available. We also provide the coordinates and identifiers for each counterpart we found from hard X-rays to the near-infrared, including 111 counterparts from the recent Gaia DR3 catalogue.

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“…There are also more than 160 confirmed and candidate Be X-ray binaries (BeXRBs; Raguzova & Popov 2005), 12 which are mostly Be+NS systems that probably evolved in a similar fashion as the Be+sdO binaries but from more massive progenitor systems (Reig 2011). The Be primaries occupy a narrow range between O9 and B2 in spectral type (Reig et al 2017). These systems are conspicuous due to the X-ray emission resulting from the (episodic) accretion of Be disk material onto the compact object, so that the sample is drawn from a much larger (partly extragalactic) volume.…”

Section: Introductionmentioning

confidence: 99%

Dynamical Masses of the Primary Be Star and Secondary sdB Star in the Single-lined Binary κ Dra (B6 IIIe)

Klement

Baade

Rivinius

et al. 2022

ApJ

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Because many classical Be stars may owe their nature to mass and angular-momentum transfer in a close binary, the present masses, temperatures, and radii of their components are of high interest for comparison to stellar evolution models. Object κ Dra is a 61.5 day single-lined binary with a B6 IIIe primary. With the CHARA Array instruments MIRC/MIRC-X and MYSTIC, we detected the secondary at (approximately photospheric) flux ratios of 1.49% ± 0.10% and 1.63% ± 0.09% in the H and K band, respectively. From a large and diverse optical spectroscopic database, only the radial velocity curve of the Be star could be extracted. However, employing the parallaxes from Hipparcos and Gaia, which agree within their nominal 1σ errors, we could derive the total mass and found component masses of 3.65 ± 0.48 and 0.426 ± 0.043 M ⊙ for the Be star and the companion, respectively. Previous cross-correlation of the observed FUV spectrum with O-type subdwarf (sdO) spectral model templates had not detected a companion belonging to the hot sdO population known from ∼20 earlier-type Be stars. Guided by our full 3D orbital solution, we found a strong cross-correlation signal for a stripped subdwarf B-type companion (FUV flux ratio of 2.3% ± 0.5%), enabling the first firm characterization of such a star and making κ Dra the first mid- to late-type Be star with a directly observed subdwarf companion.

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The optical counterpart to the Be/X-ray binary SAX J2239.3+6116

Cited by 8 publications

References 56 publications

Fast time optical variability in Be/X-ray binaries

Fast time optical variability in Be/X-ray binaries

A catalogue of high-mass X-ray binaries in the Galaxy: from the INTEGRAL to theGaiaera

Dynamical Masses of the Primary Be Star and Secondary sdB Star in the Single-lined Binary κ Dra (B6 IIIe)

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