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Infrared Spectroscopy Of The Merger Candidate Kic 9832227
Title
Infrared Spectroscopy Of The Merger Candidate Kic 9832227.
Creator
Pavlenko, Ya, Evans, A., Banerjee, D. P. K., Southworth, J., Shahbandeh, M., Davis, S.
Abstract/Description
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...
Show moreContext. 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 mu m, 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 log g, and the strength of the Can 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 Can triplet is also likely chromospheric in origin.
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Date Issued
2018-07-24
Identifier
FSU_libsubv1_wos_000439936700009, 10.1051/0004-6361/201832717
Format
Citation
Two Transitional Type Ia Supernovae Located In The Fornax Cluster Member Ngc 1404
Title
Two Transitional Type Ia Supernovae Located In The Fornax Cluster Member Ngc 1404: Sn 2007on And Sn 2011iv.
Creator
Gall, C., Stritzinger, M. D., Ashall, C., Baron, E., Burns, C. R., Hoeflich, P., Hsiao, E. Y., Mazzali, P. A., Phillips, M. M., Filippenko, A. V., Anderson, J. P., Benetti, S.,...
Show moreGall, C., Stritzinger, M. D., Ashall, C., Baron, E., Burns, C. R., Hoeflich, P., Hsiao, E. Y., Mazzali, P. A., Phillips, M. M., Filippenko, A. V., Anderson, J. P., Benetti, S., Brown, P. J., Campillay, A., Challis, P., Contreras, C., Elias de la Rosa, N., Folatelli, G., Foley, R. J., Fraser, M., Holmbo, S., Marion, G. H., Morrell, N., Pan, Y.-C., Pignata, G., Suntzeff, N. B., Taddia, F., Torres Robledo, S., Valenti, S.
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Abstract/Description
We present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band light curves of SN 2007on and SN 2011iv are characterised by Delta m(15)(B) decline-rate values of 1.96 mag and 1.77 mag, respectively. Although they have similar decline rates, their peak B-and H-band magnitudes di ff er by similar to 0.60 mag and similar to 0.35 mag, respectively. After...
Show moreWe present an analysis of ultraviolet (UV) to near-infrared observations of the fast-declining Type Ia supernovae (SNe Ia) 2007on and 2011iv, hosted by the Fornax cluster member NGC 1404. The B-band light curves of SN 2007on and SN 2011iv are characterised by Delta m(15)(B) decline-rate values of 1.96 mag and 1.77 mag, respectively. Although they have similar decline rates, their peak B-and H-band magnitudes di ff er by similar to 0.60 mag and similar to 0.35 mag, respectively. After correcting for the luminosity vs. decline rate and the luminosity vs. colour relations, the peak B-band and H-band light curves provide distances that di ff er by similar to 14% and similar to 9%, respectively. These findings serve as a cautionary tale for the use of transitional SNe Ia located in early-type hosts in the quest to measure cosmological parameters. Interestingly, even though SN 2011iv is brighter and bluer at early times, by three weeks past maximum and extending over several months, its B - V colour is 0.12 mag redder than that of SN 2007on. To reconcile this unusual behaviour, we turn to guidance from a suite of spherical one-dimensional Chandrasekhar-mass delayed-detonation explosion models. In this context, Ni-56 production depends on both the so-called transition density and the central density of the progenitor white dwarf. To first order, the transition density drives the luminosity-width relation, while the central density is an important second-order parameter. Within this context, the di ff erences in the B - V colour evolution along the Lira regime suggest that the progenitor of SN 2011iv had a higher central density than SN 2007on.
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Date Issued
2018-03-27
Identifier
FSU_libsubv1_wos_000428423300002, 10.1051/0004-6361/201730886
Format
Citation