Multiple Outflows in the Giant Eruption of a Massive Star

TL;DR

This paper studies a giant eruption in a massive star, revealing multiple outflows with different velocities, and discusses the evolution, possible progenitor, and implications for understanding such stellar events.

Contribution

It provides detailed spectral analysis of multiple outflows in a giant eruption, highlighting their possible common origin and suggesting such phenomena may be more prevalent than previously thought.

Findings

Detection of multiple outflow velocities in the eruption.

Identification of a potential progenitor star.

Evidence that multiple outflows may be common in giant eruptions.

Abstract

The supernova impostor PSN J09132750+7627410 in NGC 2748 reached a maximum luminosity of approximately -14 mag. It was quickly realized that its was not a true supernova, but another example of a non-terminal giant eruption. PSN J09132750+7627410 is distinguished by multiple P Cygni absorption minima in the Balmer emission lines that correspond to outflow velocities of -400, -1100, and -1600 km/s. Multiple outflows have been observed in only a few other objects. In this paper we describe the evolution of the spectrum and the P Cygni profiles for three months past maximum, the post-maximum formation of a cool, dense wind, and the identification of a possible progenitor. One of the possible progenitors is an infrared source. Its pre-eruption spectral energy distribution suggests a bolometric luminosity of -8.3 mag and a dust temperature of 780 degrees K. If it is the progenitor it is above the AGB limit unlike the intermediate luminosity red transients. The three P Cygni profiles could be due to ejecta from the current eruption, the wind of the progenitor, or previous mass loss events. We suggest that they were all formed as part of the same high mass loss event and are due to material ejected at different velocities or energies. We also suggest that multiple outflows during giant eruptions may be more common than reported.