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Photometric and Spectroscopic Properties of Type Ia Supernova 2018oh with Early Excess Emission from the Kepler 2 Observations

2018; IOP Publishing; Volume: 870; Issue: 1 Linguagem: Inglês

10.3847/1538-4357/aaec74

1538-4357

Wenxiong Li, Xiaofeng Wang, J. Vinkó, J. Mo, G. Hosseinzadeh, David J. Sand, Jujia Zhang, H. Lin, Jujia Zhang, Lingzhi Wang, Jujia Zhang, Zhihao Chen, Danfeng Xiang, L. Rui, Fan Huang, Xue Li, Xiaodan Zhang, L. Li, E. Baron, James M. DerKacy, Xulin Zhao, H. Sai, Kaicheng Zhang, Lingzhi Wang, D. A. Howell, C. McCully, I. Arcavi, S. Valenti, D. Hiramatsu, J. Burke, A. Rest, P. Garnavich, B. Tucker, Gautham Narayan, E. Shaya, S. Margheim, A. Zenteno, V. Ashley Villar, G. Dimitriadis, R. J. Foley, Y. C. Pan, D. A. Coulter, Ori D. Fox, Saurabh W. Jha, D. O. Jones, Daniel Kasen, C. D. Kilpatrick, Anthony L. Piro, Adam G. Riess, C. Rojas-Bravo, B. J. Shappee, T. W. S. Holoien, K. Z. Stanek, M. R. Drout, Katie Auchettl, C. S. Kochanek, J. S. Brown, S. Bose, D. Bersier, J. Brimacombe, Ping Chen, Subo Dong, S. Holmbo, J. A. Muñoz, R. L. Mutel, R. S. Post, J. L. Prieto, J. Shields, D. Tallon, Todd A. Thompson, P. Vallely, Steven Villanueva, S. J. Smartt, K. W. Smith, K. C. Chambers, H. Flewelling, M. E. Huber, E. A. Magnier, C. Waters, A. S. B. Schultz, J. Bulger, T. Lowe, M. Willman, K. Sárneczky, András Pál, J. C. Wheeler, Attila Bódi, Zsófia Bognár, B. Csák, B. Cseh, G. Csörnyei, O. Hanyecz, Bernadett Ignácz, Csilla Kalup, Réka Könyves-Tóth, L. Kriskovics, A. Ordasi, I. Rajmon, Á. Sódor, R. Szabó, R. Szakáts, Gabriella Zsidi, Peter Milne, Jennifer E. Andrews, Nathan Smith, Christopher Bilinski, P. J. Brown, J. Nordin, S. C. Williams, L. Galbany, J. Palmerio, I. Hook, C. Inserra, K. Maguire, R. Cartier, Alessandro Razza, C. P. Gutiérrez, J. J. Hermes, Joshua S. Reding, Benjamin C. Kaiser, J. Tonry, A. Heinze, L. Denneau, H. Weiland, B. Stalder, Geert Barentsen, Jessie L. Dotson, Thomas Barclay, Michael Gully-Santiago, Christina Hedges, Ann Marie Cody, Steve B. Howell, Jeffrey L. Coughlin, Jeffrey E. Van Cleve, Josè Vinícius de Miranda Cardoso, K. A. Larson, K. M. McCalmont-Everton, C. Peterson, S. Ross, Lee Reedy, Darren Osborne, Chris McGinn, L. Kohnert, Lucas F. Migliorini, A. Wheaton, Brittany Spencer, C. Labonde, G. A. Rodrıguez Castillo, G. Beerman, K. Steward, M. Hanley, R. Larsen, R. Gangopadhyay, R. Kloetzel, T. Weschler, V. Nystrom, J. Moffatt, M. Redick, K. Griest, M. Packard, M. Muszynski, Jennifer Kampmeier, R. Bjella, S. Flynn, B. Elsaesser,

Astrophysics and Cosmic Phenomena

Abstract Supernova (SN) 2018oh (ASASSN-18bt) is the first spectroscopically confirmed Type Ia supernova (SN Ia) observed in the Kepler field. The Kepler data revealed an excess emission in its early light curve, allowing us to place interesting constraints on its progenitor system. Here we present extensive optical, ultraviolet, and near-infrared photometry, as well as dense sampling of optical spectra, for this object. SN 2018oh is relatively normal in its photometric evolution, with a rise time of 18.3 ± 0.3 days and Δ m 15 ( B ) = 0.96 ± 0.03 mag, but it seems to have bluer B − V colors. We construct the “UVOIR” bolometric light curve having a peak luminosity of 1.49 × 10 43 erg s −1 , from which we derive a nickel mass as 0.55 ± 0.04 M ⊙ by fitting radiation diffusion models powered by centrally located 56 Ni. Note that the moment when nickel-powered luminosity starts to emerge is +3.85 days after the first light in the Kepler data, suggesting other origins of the early-time emission, e.g., mixing of 56 Ni to outer layers of the ejecta or interaction between the ejecta and nearby circumstellar material or a nondegenerate companion star. The spectral evolution of SN 2018oh is similar to that of a normal SN Ia but is characterized by prominent and persistent carbon absorption features. The C ii features can be detected from the early phases to about 3 weeks after the maximum light, representing the latest detection of carbon ever recorded in an SN Ia. This indicates that a considerable amount of unburned carbon exists in the ejecta of SN 2018oh and may mix into deeper layers.