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Infrared spectroscopy of the merger candidate KIC 9832227

Pavlenko, Ya.V.; Evans, A.; Banerjee, D.P.K.; Southworth, J.; Shahbandeh, M.; Davis, S.

Infrared spectroscopy of the merger candidate KIC 9832227 Thumbnail


Ya.V. Pavlenko

A. Evans

D.P.K. Banerjee

M. Shahbandeh

S. Davis


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.

Journal Article Type Article
Acceptance Date Apr 4, 2018
Online Publication Date Jul 24, 2018
Publication Date 2018-07
Journal Astronomy and Astrophysics
Print ISSN 2329-1273
Publisher Hans Publishers
Peer Reviewed Peer Reviewed
Volume 615
Article Number A120
Keywords circumstellar matter, binaries, close—binaries, eclipsing, stars, individual (KIC9832227), infrared
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