The Dusty Aftermath of the V1309 Sco Binary Merger

TL;DR

This paper studies the dust formation and properties in the aftermath of the V1309 Sco binary merger using mid-infrared observations, revealing dust composition, grain size, and temperature, and discussing its circumstellar configuration.

Contribution

It provides the first mid-IR spectra and photometry of V1309 Sco post-merger, constraining dust composition, grain size, and temperature, and discusses dust processing in the circumstellar environment.

Findings

Detected significant dust emission and absorption features.

Constrained dust to be large amorphous pyroxene grains at 800 K.

Indicated possible dust processing and circumstellar disk or shell structure.

Abstract

We present mid-IR photometry and spectra of the merged binary V1309 Sco taken between 18 and 23 months after outburst. Strong mid-IR emission and a solid state absorption feature indicate the presence of a significant amount of dust in the circumstellar environment. The absence of detectable mid-IR emission before the outburst suggests this dust was produced in the eruptive merger event. Model fits to the solid state absorption feature constrain the constituent species and column density of the dust around V1309 Sco. We find the absorption feature can be reproduced by large (3 micron) amorphous pyroxene grains at a temperature of 800 K. This grain size, if confirmed with longer wavelength spectroscopy and modelling, would be suggestive of dust processing in the circumstellar environment. The data in hand do not allow us to discriminate between disk or shell configurations for the dusty material.