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UIR-band emission from M supergiants

SYLVESTER, RJ; BARLOW, MJ; SKINNER, CJ; (1994) UIR-band emission from M supergiants. Monthly Notices of the Royal Astronomical Society , 266 (3) pp. 640-648. 10.1093/mnras/266.3.640. Green open access

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We have obtained 10−μm spectra of 16 M supergiants, 15 of them in the h and χ Per association. All of the stars exhibit silicate emission features, but in addition seven of the stars show narrow UIR (unidentified infrared) band emission features, at 11.3 μm⁠, 8.65 μm and other wavelengths, which are normally associated with carbon-rich media. Not only are these the coolest objects to have been found to exhibit UIR-band emission, but the outflows from these classical oxygen-rich stars should form only O-rich particles according to equilibrium condensation theory. We interpret our results in terms of the non-equilibrium chemistry model by Beck et al., whereby chromospheric UV radiation can liberate some atomic carbon via the photodissociation of CO molecules, enabling the formation of carbon-rich species as well as silicates. Such a chromospheric UV radiation field could also provide the photons needed to excite the observed UIR-band emission.

Type: Article
Title: UIR-band emission from M supergiants
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/266.3.640
Publisher version: https://doi.org/10.1093/mnras/266.3.640
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: molecular processes, circumstellar matter, supergiants, dust, extinction, infrared: stars
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10096173
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