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Extremely broad emission wings at H$\beta$ and H$\alpha$ have been found inVFTS data for five very luminous BA supergiants in or near 30 Doradus in theLarge Magellanic Cloud. The profiles of both lines are extremely asymmetrical,which we have found to be caused by very broad diffuse interstellar bands(DIBs) in the longward wing of H$\beta$ and the shortward wing of H$\alpha$.These DIBs are well known to interstellar but not to many stellar specialists,so that the asymmetries may be mistaken for intrinsic features. The broademission wings are generally ascribed to electron scattering, although we notedifficulties for that interpretation in some objects. Such profiles are knownin some Galactic hyper/supergiants and are also seen in both active andquiescent Luminous Blue Variables. No prior or current LBV activity is known inthese 30 Dor stars, although a generic relationship to LBVs is not excluded;subject to further observational and theoretical investigation, it is possiblethat these very luminous supergiants are approaching the LBV stage for thefirst time. Their locations in the HRD and presumed evolutionary tracks areconsistent with that possibility. The available evidence for spectroscopicvariations of these objects is reviewed, while recent photometric monitoringdoes not reveal variability. A search for circumstellar nebulae has beenconducted, with an indeterminate result for one of them.

astrophysical journal/the astrophysical journal

Broad Balmer Wings in BA Hyper/Supergiants Distorted by Diffuse  Interstellar Bands: Five Examples in the 30 Doradus Region from the  VLT-FLAMES Tarantula Survey