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The sudden appearance of CO emission in LHA 115-S 65

Authors

  • M. E. Oksala,

    Corresponding author
    1. Astronomickýústav, Akademie věd České republiky, Fričova 298, 251 65 Ondřejov, Czech Republic
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  • M. Kraus,

    1. Astronomickýústav, Akademie věd České republiky, Fričova 298, 251 65 Ondřejov, Czech Republic
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  • M. L. Arias,

    1. Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
    2. Instituto de Astrofísica de La Plata, CCT La Plata, CONICET-UNLP, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
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  • M. Borges Fernandes,

    1. Observatório Nacional, Rua General José Cristino 77, 20921-400 São Cristovão, Rio de Janeiro, Brazil
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  • L. Cidale,

    1. Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
    2. Instituto de Astrofísica de La Plata, CCT La Plata, CONICET-UNLP, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
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  • M. F. Muratore,

    1. Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
    2. Instituto de Astrofísica de La Plata, CCT La Plata, CONICET-UNLP, Paseo del Bosque s/n, B1900FWA La Plata, Argentina
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  • M. Curé

    1. Departmento de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso Av. Gran Bretaña 1111, Casilla 5030, Valparaíso, Chile
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  • Based on observations obtained with ESO telescopes at the La Silla Paranal Observatory under programme ID 088.D-044 and at the Gemini Observatory which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (USA), the Science and Technology Facilities Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), under programme ID GS-2010B-Q-31.

E-mail: oksala@sunstel.asu.cas.cz

ABSTRACT

Molecular emission has been detected in several Magellanic Cloud B[e] supergiants. In this Letter, we report on the detection of CO band head emission in the B[e] supergiant LHA 115-S 65, and present a K-band near-infrared spectrum obtained with the Spectrograph for INtegral Field Observation in the Near-Infrared (SINFONI; R= 4500) on the ESO VLT UT4 telescope. The observed molecular band head emission in S65 is quite surprising in the light of a previous non-detection by McGregor, Hyland & McGinn, as well as a high-resolution (R= 50 000) Gemini/Phoenix spectrum of this star taken nine months earlier showing no emission. Based on analysis of the optical spectrum by Kraus, Borges Fernandes & de Araújo, we suspect that the sudden appearance of molecular emission could be due to density build-up in an outflowing viscous disc, as seen for Be stars. This new discovery, combined with variability in two other similar evolved massive stars, indicates an evolutionary link between B[e] supergiants and luminous blue variables.

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