The evolution of luminous red nova at 2017jfs in NGC4470?

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Date
2019-01-01
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en
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Astronomy and Astrophysics, Volume 625
Abstract
We present the results of our photometric and spectroscopic follow-up of the intermediate-luminosity optical transient AT 2017jfs. At peak, the object reaches an absolute magnitude of Mg = -15:46 ± 0:15 mag and a bolometric luminosity of 5:5 × 1041 erg s-1. Its light curve has the doublepeak shape typical of luminous red novae (LRNe), with a narrow first peak bright in the blue bands, while the second peak is longer-lasting and more luminous in the red and near-infrared (NIR) bands. During the first peak, the spectrum shows a blue continuum with narrow emission lines of H and Fe II. During the second peak, the spectrum becomes cooler, resembling that of a K-type star, and the emission lines are replaced by a forest of narrow lines in absorption. About 5 months later, while the optical light curves are characterized by a fast linear decline, the NIR ones show a moderate rebrightening, observed until the transient disappears in solar conjunction. At these late epochs, the spectrum becomes reminiscent of that of M-type stars, with prominent molecular absorption bands. The late-time properties suggest the formation of some dust in the expanding common envelope or an IR echo from foreground pre-existing dust. We propose that the object is a common-envelope transient, possibly the outcome of a merging event in a massive binary, similar to NGC4490-2011OT1.
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Binaries: Close, Stars: Massive, Stars: winds, outflows, Supernovae: Individual: AT 2017jfs, Supernovae: Individual: NGC440-2011OT1
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Citation
Pastorello, A, Chen, T W, Cai, Y Z, Morales-Garoffolo, A, Cano, Z, Mason, E, Barsukova, E A, Benetti, S, Berton, M, Bose, S, Bufano, F, Callis, E, Cannizzaro, G, Cartier, R, Chen, P, Dong, S, Dyrbye, S, Elias-Rosa, N, Flörs, A, Fraser, M, Geier, S, Goranskij, V P, Kann, D A, Kuncarayakti, H, Onori, F, Reguitti, A, Reynolds, T, Losada, I R, Sagués Carracedo, A, Schweyer, T, Smartt, S J, Tatarnikov, A M, Valeev, A F, Vogl, C, Wevers, T, De Ugarte Postigo, A, Izzo, L, Inserra, C, Kankare, E, Maguire, K, Smith, K W, Stalder, B, Tartaglia, L, Thöne, C C, Valerin, G & Young, D R 2019, ' The evolution of luminous red nova at 2017jfs in NGC4470? ', Astronomy and Astrophysics, vol. 625, 201935511 . https://doi.org/10.1051/0004-6361/201935511