The galactic unclassified B[e] star HD 50138

Fernandes, M. Borges; Kraus, M.; Chesneau, O.; Souza, A. Domiciano de; Araújo, F. X. de; Stee, Philippe; Meilland, A.

doi:10.1051/0004-6361/200811318

Cited by 25 publications

(32 citation statements)

References 42 publications

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“…The line also shows a strong variability. An inverse P Cygni profile was reported by Bopp (1993) in spectra taken in 1992 and by Borges Fernandes et al (2009) in the FEROS spectra from 27 October 1999. The absorption with a weak violet wing was described by Jaschek & Andrillat (1998) in spectra taken between 1989 and 1996 at Haute Provence observatory.…”

Section: He I λλ 5876 and 6678 å Linesmentioning

confidence: 75%

Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon

Jeřabková

Korčáková

Мирошниченко

et al. 2016

A&A

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Context. B[e] stars are anomalous objects around which extended circumstellar matter is present. The observed properties of the central star are significantly affected by the surrounding material. Therefore, the use of standard synthetic spectra is disputable in this case and our capability to study these objects is limited. One of the possibilities is to analyse variations of the spectral features. Long-term spectroscopic observations are required for this, but are not found in the literature. For our study we choose the B[e] star HD 50138 of the FS CMa type because of the indication that this star is a post-main-sequence star, although still not highly evolved. Therefore, it can be a good object for testing evolutionary models. Currently, HD 50138 is the most extensively observed FS CMa star which makes it an ideal object for modelling. Our observations fill the gap in the available data. Aims. To describe the variability of HD 50138 we have monitored this star spectroscopically over the last twenty years. To search for the periodicity on short-term scales, series of night-to-night observations were also obtained. We were able to obtain 130 spectra from four different telescopes -1. periods of 3000 ± 500 and 5000 ± 1000 days were detected there. We were able to catch moving humps in the Hα line, which reveal the rotating media around the star. An analysis of the correlation of equivalent widths, radial velocities, relative fluxes, and V/R ratios for various lines is presented in detail. Conclusions. We describe the spectral variability of HD 50138 over the last twenty years. Based on these data, we determine new restrictions for future modelling. We confirm the quasi-periodic behaviour of the object's spectral variability, which probably reflects mass transfer in a binary system. This behaviour also supports a recently introduced explanation of the nature of FS CMa stars as post-merger systems.

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Section: He I λλ 5876 and 6678 å Linesmentioning

confidence: 75%

Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon

Jeřabková

Korčáková

Мирошниченко

et al. 2016

A&A

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“…without a disk) are not able to reproduce the data (χ 2 of 15 to 250 for the different sub-epochs). Previous spectroscopic observational campaigns do not show any binary signal (Corporon & Lagrange 1999;Borges Fernandes et al 2009) but they do not discard this possibility. From the parametric fit in Sect.…”

Section: A Binary?mentioning

confidence: 85%

A disk asymmetry in motion around the B[e] star MWC158

Kluska

Benisty

Soulez

et al. 2016

A&A

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Context. MWC158 is a star with the B[e] phenomenon that shows strong spectrophotometric variability (in lines and in UV and visible continuum) attributed to phases of shell ejection. The evolutionary stage of this star was never clearly determined. Previous interferometric, spectropolarimetric and spectro-interferometric studies suggest a disk morphology for its environment. Aims. We investigate the origin of the variability within the inner astronomical unit of the central star using near-infrared interferometric observations with PIONIER at the VLTI over a two-year period. Methods. We performed an image reconstruction of the circumstellar environment using the SPARCO method. We discovered that the morphology of the circumstellar environment could vary on timescales of weeks or days. We carried out a parametric fit of the data with a model consisting of a star, a disk and a bright spot that represents a brighter emission in the disk. Results. We detect strong morphological changes in the first astronomical unit around the star, that happen on a timescale of few months. We cannot account for such variability well with a binary model. Our parametric model fits the data well and allows us to extract the location of the asymmetry for different epochs. Conclusions. For the first time, we detect a morphological variability in the environment of MWC158. This variability is reproduced by a model of a disk and a bright spot. The locations of the bright spot suggest that it is located in the disk, but its precise motion is not determined. The origin of the asymmetry in the disk is complex and may be related to asymmetric shell ejections.

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“…One of these methods was described by Borges Fernandes et al (2009), where through the observed color indices, it is possible to derive the intrinsic ones, such as (U − B)0 and (B − V )0, and the total extinction of each object (hereafter Method 1).…”

Section: Spectral Classificationmentioning

confidence: 99%

The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds†

Condori

Fernandes

Kraus

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We investigated 12 unclassified B[e] stars or candidates, 8 from the Galaxy, 2 from the Large Magellanic Cloud (LMC) and 2 from the Small Magellanic Cloud (SMC). Based on the analysis of high-resolution spectroscopic (FEROS) and photometric data, we confirmed the presence of the B[e] phenomenon for all objects of our sample, except for one (IRAS 07455-3143). We derived their effective temperature, spectral type, luminosity class, interstellar extinction and, using the distances from Gaia DR2, we obtained their bolometric magnitude, luminosity and radius. Modeling of the forbidden lines present in the FEROS spectra revealed information about the kinematics and geometry of the circumstellar medium of these objects. In addition, we analyzed the light curves of four stars, finding their most probable periods. The evolutionary stage of 11 stars of our sample is suggested from their position on the HR diagram, taking into account evolutionary tracks of stars with solar, LMC and SMC metallicities. As results, we identified B and B[e] supergiants, B[e] stars probably at the main sequence or close to its end, post-AGB and HAeB[e] candidates, and A[e] stars in the main sequence or in the pre-main sequence. However, our most remarkable results are the identification of the third A[e] supergiant (ARDB 54, the first one in the LMC), and of an "LBV impostor" in the SMC (LHA 115-N82).

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The galactic unclassified B[e] star HD 50138

Cited by 25 publications

References 42 publications

Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon

Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon

A disk asymmetry in motion around the B[e] star MWC158

The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds†

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