iPTF14hls as a variable hyper-wind from a very massive star

Takashi J. Moriya, Paolo A. Mazzali, Elena Pian

Published 2019-11-05Version 1

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-year bright phase was more than a few Msun/yr ("hyper-wind") and it reached as much as 10 Msun/yr. The total mass lost over two years was about 10 Msun. Interestingly, we find that the light curve of iPTF14hls has a very similar shape to that of eta Carinae during the Great Eruption, which also experienced a similar but less extreme brightening accompanied by extraordinary mass loss, shedding more than 10 Msun in 10 years. The progenitor of iPTF14hls is less than 150 Msun if it still exists, which is similar to eta Carinae. The two phenomena may be related to a continuum-driven extreme wind from very massive stars.