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Abstract:
The origin of iPTF14hls, which had Type IIP supernova-like spectra but kept bright for almost two years with little spectral evolution, is still unclear. We here propose that iPTF14hls was not a sudden outburst like supernovae but rather a long-term outflow similar to stellar winds. The properties of iPTF14hls, which are at odds with a supernova scenario, become natural when interpreted as a stellar wind with variable mass-loss rate. Based on the wind hypothesis, we estimate the mass-loss rates of iPTF14hls in the bright phase. We find that the instantaneous mass-loss rate of iPTF14hls during the 2-yr bright phase was more than a few M⊙ yr−1 (‘hyper-wind’) and it reached as much as 10 M⊙ yr−1 . The total mass lost over two years was about 10 M⊙. Interestingly, we find that the light curve of iPTF14hls has a very similar shape to that of η Carinae during the Great Eruption, which also experienced a similar but less extreme brightening accompanied by extraordinary mass-loss, shedding more than 10 M⊙ in 10 yr. The progenitor of iPTF14hls is less than 150 M⊙ if it still exists, which is similar to η Carinae. The two phenomena may be related to a continuum-driven extreme wind from very massive stars.
