Confirmation of the Luminous Blue Variable Status of MWC 930

Мирошниченко, А. С.; Manset, N.; Zharikov, S. V.; Zsargó, Janos; Jiménez, Janette Magalli Murillo; Groh, J. H.; Levato, H.; Grosso, M.; Rudy, R. J.; Laag, Edward A.; Crawford, K.B.; Puetter, R. C.; Reichart, D.; Ivarsen, K.; Haislip, J.; Nysewander, M.; Lacluyzé, A.

doi:10.1155/2014/130378

Cited by 6 publications

(2 citation statements)

References 18 publications

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“…Both objects are confirmed LBVs. MWC 930 shows spectral variability and its spectral lines are broad and show splitting (Miroshnichenko et al 2005(Miroshnichenko et al , 2014. Lobel et al (2017) attributed this line splitting to optically thick central line emission produced in the inner ionized wind region.…”

Section: Multiplicity Criteriamentioning

confidence: 99%

Multiplicity of Galactic luminous blue variable stars

Mahy

Lanthermann

Hutsemékers

et al. 2021

A&A

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Context. Luminous blue variables (LBVs) are characterised by strong photometric and spectroscopic variability. They are thought to be in a transitory phase between O-type stars on the main sequence and the Wolf-Rayet stage. Recent studies also evoked the possibility that they might be formed through binary interaction. Only a few are known in binary systems so far, but their multiplicity fraction is still uncertain. Aims. We derive the binary fraction of the Galactic LBV population. We combine multi-epoch spectroscopy and long-baseline interferometry to probe separations from 0.1 to 120 mas around confirmed and candidate LBVs. Methods. We used a cross-correlation technique to measure the radial velocities of these objects. We identified spectroscopic binaries through significant radial velocity variability with an amplitude larger than 35 km s−1. We also investigated the observational biases to take them into account when we established the intrinsic binary fraction. We used CANDID to detect interferometric companions, derive their flux fractions, and their positions on the sky. Results. From the multi-epoch spectroscopy, we derive an observed spectroscopic binary fraction of 26−10+16%. Considering period and mass ratio ranges from log(Porb) = 0 − 3 (i.e. from 1 to 1000 days), q = 0.1 − 1.0, and a representative set of orbital parameter distributions, we find a bias-corrected binary fraction of 62−24+38%. Based on data of the interferometric campaign, we detect a binary fraction of 70 ± 9% at projected separations between 1 and 120 mas. Based on the derived primary diameters and considering the distances of these objects, we measure for the first time the exact radii of Galactic LBVs to be between 100 and 650 R⊙. This means that it is unlikely that short-period systems are included among LBV-like stars. Conclusions. This analysis shows for the first time that the binary fraction in the Galactic LBV population is large. If they form through single-star evolution, their orbit must be large initially. If they form through a binary channel, the implication is that either massive stars in short binary systems must undergo a phase of fully non-conservative mass transfer to be able to sufficiently widen the orbit to form an LBV, or that LBVs form through merging in initially binary or triple systems. Interferometric follow-up would provide the distributions of orbital parameters at more advanced stages and would serve to quantitatively test the binary evolution in massive stars.

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Section: Multiplicity Criteriamentioning

confidence: 99%

Multiplicity of Galactic luminous blue variable stars

Mahy

Lanthermann

Hutsemékers

et al. 2021

A&A

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“…d References with examples of photometry and/or spectra of LBVs/cLBVs. (1) Wolf & Stahl (1982); Miroshnichenko et al (2014). (2) Walborn et al (2017).…”

Section: Ngc 7793mentioning

confidence: 99%

Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy

Wofford

Ramírez

Boquien

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Only about 19 Galactic and 25 extra-galactic bona-fide Luminous Blue Variables (LBVs) are known to date. This incomplete census prevents our understanding of this crucial phase of massive star evolution which leads to the formation of heavy binary black holes via the classical channel. With large samples of LBVs one could better determine the duration and maximum stellar luminosity which characterize this phase. We search for candidate LBVs (cLBVs) in a new galaxy, NGC 7793. For this purpose, we combine high spatial resolution images from two Hubble Space Telescope (HST) programs with optical spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE). By combining PSF-fitting photometry measured on F547M, F657N, and F814W images, with restrictions on point-like appearance (at HST resolution) and Hα luminosity, we find 100 potential cLBVs, 36 of which fall in the MUSE fields. Five of the latter 36 sources are promising cLBVs which have M V ≤ −7 and a combination of: Hα with a P-Cygni profile; no [O i] λ6300 emission; weak or no [O iii] λ5007 emission; large [N ii]/Hα relative to H ii regions; and [S ii] λ6716/[S ii] λ6731 ∼ 1.It is not clear if these five cLBVs are isolated from O-type stars, which would favor the binary formation scenario of LBVs. Our study, which approximately covers one fourth of the optical disc of NGC 7793, demonstrates how by combining the above HST surveys with multi-object spectroscopy from 8-m class telescopes, one can efficiently find large samples of cLBVs in nearby galaxies.

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GaiaDR2 study of Herbig Ae/Be stars

Vioque

Oudmaijer

Baines

et al. 2018

A&A

181

313

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Aims. We use Gaia Data Release 2 (DR2) to place 252 Herbig Ae/Be stars in the HR diagram and investigate their characteristics and properties. Methods. For all known Herbig Ae/Be stars with parallaxes in Gaia DR2, we collected their atmospheric parameters and photometric and extinction values from the literature. To these data we added near-and mid-infrared photometry, collected Hα emission line properties such as equivalent widths and line profiles, and their binarity status. In addition, we developed a photometric variability indicator from Gaia's DR2 information.Results. We provide masses, ages, luminosities, distances, photometric variabilities and infrared excesses homogeneously derived for the most complete sample of Herbig Ae/Be stars to date. We find that high mass stars have a much smaller infrared excess and have much lower optical variabilities compared to lower mass stars, with the break at around 7M . Hα emission is generally correlated with infrared excess, with the correlation being stronger for infrared emission at wavelengths tracing the hot dust closest to the star. The variability indicator as developed by us shows that ∼25% of all Herbig Ae/Be stars are strongly variable. We observe that the strongly variable objects display doubly peaked Hα line profiles, indicating an edge-on disk.Conclusions. The fraction of strongly variable Herbig Ae stars is close to that found for A-type UX Ori stars. It had been suggested that this variability is in most cases due to asymmetric dusty disk structures seen edge-on. The observation here is in strong support of this hypothesis. Finally, the difference in dust properties occurs at 7M , while various properties traced at UV/optical wavelengths differ at a lower mass, 3M . The latter has been linked to different accretion mechanisms at work whereas the differing infrared properties and photometric variabilities are related to different or differently acting (dust-)disk dispersal mechanisms.

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Confirmation of the Luminous Blue Variable Status of MWC 930

Cited by 6 publications

References 18 publications

Multiplicity of Galactic luminous blue variable stars

Multiplicity of Galactic luminous blue variable stars

Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy

GaiaDR2 study of Herbig Ae/Be stars

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