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

作者：Walborn Nolan R^*; Sana Hugues; Evans Christopher J; Taylor William D; Sabbi Elena; Barba Rodolfo H; Morrell Nidia I; Maiz Apellaniz Jesus; Sota Alfredo; Dufton Philip L; McEvoy Catherine M; Clark J Simon; Markova Nevena; Ulaczyk Krzysztof

来源：Astrophysical Journal, 2015, 809(2): 109.

DOI：10.1088/0004-637X/809/2/109

• Magellanic Clouds
• stars: early-type
• stars: massive
• stars: peculiar
• stars: variables: S Doradus
• supergiants

Extremely broad emission wings at H beta and H alpha have been found in VLT-FLAMES Tarantula Survey data for five very luminous BA supergiants in or near 30 Doradus in the Large 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 broad emission wings are generally ascribed to electron scattering, although we note difficulties for that interpretation in some objects. Such profiles are known in some Galactic hyper/supergiants and are also seen in both active and quiescent Luminous Blue Variables (LBVs). No prior or current LBV activity is known in these 30 Dor stars, although a generic relationship to LBVs is not excluded; subject to further observational and theoretical investigation, it is possible that these very luminous supergiants are approaching the LBV stage for the first time. Their locations in the HRD and presumed evolutionary tracks are consistent with that possibility. The available evidence for spectroscopic variations of these objects is reviewed, while recent photometric monitoring does not reveal variability. A search for circumstellar nebulae has been conducted, with an indeterminate result for one of them.

• 出版日期2015-8-20
• 单位中国科学院国家天文台