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

Polster, J.; Korčáková, Daniela; Manset, N.

doi:10.1051/0004-6361/201832772

Cited by 7 publications

(10 citation statements)

References 22 publications

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“…Mathew et al 2018) although Hernández et al (2004) was unable to classify it. Regarding the unclassified B[e] or FS CMa stars, almost all the confirmed FS CMa objects are listed in Lamers et al (1998), Miroshnichenko (2007), Miroshnichenko et al (2007Miroshnichenko et al ( , 2017, and Khokhlov et al (2018) (Frasca et al 2016), MWC 930 looks like a luminous blue variable (Martayan et al 2016;Jiang et al 2018) and MWC 623 seems clear to be a FS CMa star (Miroshnichenko 2007;Polster et al 2018). Therefore, we also removed these three objects from our set of known HAeBes (Sect.…”

Section: Appendix A: Disentangling Herbig Ae/be Cbe Stars and B[e] mentioning

confidence: 99%

Catalogue of new Herbig Ae/Be and classical Be stars

Vioque

Oudmaijer

Schreiner³

et al. 2020

A&A

115

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Context. The intermediate-mass pre-main sequence Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known. Aims. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects. Methods. We have applied machine learning techniques to 4 150 983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Hα emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars, with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars. Results. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8 ± 1.4% and 85.5 ± 1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude.

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Section: Appendix A: Disentangling Herbig Ae/be Cbe Stars and B[e] mentioning

confidence: 99%

Catalogue of new Herbig Ae/Be and classical Be stars

Vioque

Oudmaijer

Schreiner³

et al. 2020

A&A

115

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“…The small RV variations have been interpreted as either due to a large orbital separation between the components or to a nearly pole-on orientation of the binary and its CS disk [16,55]. The latter explanation seems to be less probable, as the system shows a high intrinsic polarization inconsistent with a high inclination angle [56].…”

Section: Mwc 623mentioning

confidence: 99%

Recent Progress in Finding Binary Systems with the B[e] Phenomenon

et al. 2023

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This paper describes recent studies of the FS CMa-type objects, a group of stars showing the B[e] phenomenon defined in 2007. The objects exhibit strong emission-line spectra with both permitted and forbidden lines suggesting the presence of a B-type star as well as strong IR excesses due to radiation of circumstellar dust. These properties are hard to explain in the framework of the evolution of single stars with luminosities between ~300 and ~30,000 L⊙ typical of most B-type stars. We explore the hypothesis that the gaseous-and-dusty envelopes of FS CMa objects are due to either earlier or ongoing mass transfer between the binary system components. It is hard to detect the secondary components in these systems because of veiling and distortions by the circumstellar matter because of the relative faintness of the companions. Nevertheless, we detected regular radial velocity variations of the spectral lines in MWC 728, 3 Pup, and AS 386 and we found absorption lines typical of cool stars in the spectra of MWC 645, AS 174, and several other objects. The diversity of the secondary components in FS CMa objects is discussed in the context of non-conservative binary evolution.

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“…The large amount of circumstellar matter is naturally explained in this case as resulting from prior or current mass transfer events. A detailed discussion of binarity is presented by ; Polster et al (2018); Miroshnichenko et al (2020b). Indeed, the periodicity, which is interpreted as the orbital motion, was found in a significant stellar sample.…”

Section: Introductionmentioning

confidence: 95%

“…The K-type spectrum may be formed through the disk, which behaves as a pseudoatmosphere. The analysis and modeling of the Hα bisector variability of MWC 623 (Polster et al 2018) favors the radiative transfer effect through the circumstellar disk. The result of this modeling is supported by the polarimetric observations of Zickgraf & Schulte-Ladbeck (1989), which indicates an edgeon view.…”

Section: Introductionmentioning

confidence: 98%

First detection of a magnetic field in low-luminosity B[e] stars

Korčáková

Sestito

Manset

et al. 2022

A&A

Self Cite

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We report the first detection of the magnetic field in a star of FS CMa type, a subgroup of objects characterized by the B[e] phenomenon. The split of magnetically sensitive lines in IRAS 17449+2320 determines the magnetic field modulus of 6.2 ± 0.2 kG. Spectral lines and their variability reveal the presence of a B-type spectrum and a hot continuum source in the visible. The hot source confirms GALEX UV photometry. Because there is a lack of spectral lines for the hot source in the visible, the spectral fitting gives only the lower temperature limit of the hot source, which is 50 000 K, and the upper limit for the B-type star of 11 100 K. The V∕R ratio of the Hα line shows quasiperiodic behavior on timescale of 800 days. We detected a strong red-shifted absorption in the wings of Balmer and O I lines in some of the spectra. The absorption lines of helium and other metals show no, or very small, variations, indicating unusually stable photospheric regions for FS CMa stars. We detected two events of material infall, which were revealed to be discrete absorption components of resonance lines. The discovery of the strong magnetic field together with the Gaia measurements of the proper motion show that the most probable nature of this star is that of a post-merger object created after the binary left its birth cluster. Another possible scenario is a magnetic Ap star around Terminal-Age Main Sequence. On the other hand, the strong magnetic field defies the hypothesis that IRAS 17449+2320 is an extreme classical Be star. Thus, IRAS 17449+2320 provides a pretext for exploring a new explanation of the nature of FS CMa stars or, at least, a group of stars with very similar spectral properties.

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

Cited by 7 publications

References 22 publications

Catalogue of new Herbig Ae/Be and classical Be stars

Catalogue of new Herbig Ae/Be and classical Be stars

Recent Progress in Finding Binary Systems with the B[e] Phenomenon

First detection of a magnetic field in low-luminosity B[e] stars

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