Issue |
A&A
Volume 615, July 2018
|
|
---|---|---|
Article Number | A120 | |
Number of page(s) | 4 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/201832717 | |
Published online | 24 July 2018 |
Infrared spectroscopy of the merger candidate KIC 9832227
1
Main Astronomical Observatory, Academy of Sciences of the Ukraine,
Golosiiv Woods,
Kyiv-127
03680, Ukraine
e-mail: yp@mao.kiev.ua
2
Astrophysics Group, Keele University,
Keele,
Staffordshire
ST5 5BG, UK
3
Physical Research Laboratory,
Navrangpura,
Ahmedabad,
Gujarat
380009, India
4
Department of Physics, Florida State University,
77 Chieftain Way,
Tallahassee,
FL
32306-4350, USA
Received:
26
January
2018
Accepted:
4
April
2018
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 (NIR) 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 (IR) spectroscopy in the wavelength range 0.7–2.5 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 IR spectrum is best fitted by a single component with effective temperature 5920 K, log[g] = 4.1, and solar metallicity, consistent with the fact that the system was observed at conjunction.
Conclusions. The strength of the IR H lines is consistent with a high value of logg, 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.
Key words: circumstellar matter – binaries: close – binaries: eclipsing – stars: individual: KIC 9832227 – infrared: stars
© ESO 2018
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