Evans, A, Pavlenko, Y, Bamerjee, D, Southworth, J, Shahbandeh, M and Scott, D (2018) Infrared spectroscopy of the merger candidate KIC 9832227. Astronomy and Astrophysics, 615. ISSN 1432-0746

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Context. It has been predicted that the object KIC 9832227 – a contact binary star – will undergo a merger in 2022.2±0.7.We describe the near infrared spectrum of this object as an impetus to obtain pre-merger data.
Aims. We aim to characterise (i) the nature of the individual components of the binary and (ii) the likely circumbinary environment, so that the merger – if and when it occurs – can be interpreted in an informed manner.
Methods. We use infrared spectroscopy in the wavelength range 0.7 μm–2.5 μm, to which we fit model atmospheres to represent the individual stars. We use the binary ephemeris to determine the orbital phase at the time of observation.
Results. We find that the infrared spectrum is best fitted by a single component having effective temperature 5 920 K, log [g] = 4.1 and solar metallicity, consistent with the fact that the system was observed at conjunction.
Conclusions. The strength of the infrared H lines is consistent with a high value of log g, and the strength of the Ca ii triplet indicates the presence of a chromosphere, as might be expected from rapid stellar rotation. The He i absorption we observe likely arises in He excited by coronal activity in a circumstellar envelope, suggesting that the weakness of the Ca ii triplet is also likely chromospheric in origin.

Item Type: Article
Additional Information: This is the accepted author manuscript (AAM). The final published version (version of record) will be available online via EDP Sciences at http://doi.org/10.1051/0004-6361/201832717 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: circumstellar matter, binaries, close—binaries, eclipsing, stars, individual (KIC9832227), infrared
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 04 Apr 2018 13:50
Last Modified: 28 Aug 2018 12:23
URI: https://eprints.keele.ac.uk/id/eprint/4707

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