An intermediate-luminosity-optical-transient (ILOT) model for the young stellar object ASASSN-15qi

TL;DR

This paper proposes a model where the outburst of young stellar object ASASSN-15qi is caused by a tidally disrupted young planet, creating an intermediate luminosity optical transient with unique properties.

Contribution

It introduces a novel ILOT model involving a young, low-density planet being tidally destroyed on a main-sequence star, explaining ASASSN-15qi's unusual outburst characteristics.

Findings

The outburst's luminosity is below that of novae.

The event is less red than typical ILOTs.

The model accounts for the hot remnant and specific energy properties.

Abstract

We construct a scenario where the outburst of the young-stellar-object ASASSN-15qi is an intermediate luminosity optical transient (ILOT). In this scenario a sub-Jupiter young planet was tidally destructed on to a young main-sequence star. The system is young, therefore the radius of the planet is larger than its final value, and consequently its density is smaller. The lower density allows the tidal destruction of the young Saturn-like planet on to the main-sequence star of mass $\approx 2.4~\rm{M_\odot}$, resulting in a formation of a disc and a gravitationally-powered ILOT. Unlike the case of the more energetic ILOT V838~Mon, the mass of the destructed planet is too low to inflate a giant envelope, and hence the merger remnant stays hot. If our suggested model holds, this ILOT possesses two interesting properties: (1) its luminosity and total energy are below those of novae, and (2) it is not as red as other ILOTs. The unusual outburst of ASASSN-15qi, if indeed is an ILOT, further increases the diversity of the already heterogeneous group of ILOTs. We mark the region on the energy-time diagram occupied by such young ILOTs.