VLTI monitoring of the dust formation event of the Nova V1280 Sco

TL;DR

This study presents high-resolution interferometric monitoring of dust formation in nova V1280 Sco, revealing the dust shell expansion, ejection timing, and mass, with implications for understanding nova dust production.

Contribution

First high-resolution interferometric monitoring of V1280 Sco's dust formation, providing detailed expansion and mass estimates, and revealing complex dust shell behavior.

Findings

Dust shell expands at 0.35 mas/day

Ejection occurred around 10.5 days after maximum brightness

Total ejected dust mass exceeds 10^-4 solar masses

Abstract

We present the first high spatial resolution monitoring of the dust forming nova V1280 Sco performed with the Very Large Telescope Interferometer (VLTI). Spectra and visibilities were obtained from the onset of the dust formation 23 days after discovery till day 145, using the instruments AMBER and MIDI. These interferometric observations are complemented by near-infrared data from the 1.2m Mt. Abu Infrared Observatory, India. The observations are first interpreted with simple models but more complex models, involving a second shell, are necessary to explain the data obtained from t=110d after outburst. This behavior is in accordance with the light curve of V1280 Sco which exhibits a secondary peak around t=106d, followed by a new steep decline, suggesting a new dust forming event. Spherical dust shell models generated with the DUSTY code are also used to investigate the parameters of the main dust shell. Using uniform disk and Gaussian models, these observations allow us to determine an apparent linear expansion rate for the dust shell of 0.35 +/- 0.03 mas/day and the approximate time of ejection of the matter in which dust formed as t_ejec=10.5+/-7d, i.e. close to the maximum brightness. This information, combined with the expansion velocity of 500+/-100km/s, implies a distance estimate of 1.6+/-0.4kpc. The dust mass generated was typically 2-8 10^-9 solar mass per day. Considering that the dust forming event lasted at least 200-250d, the mass of the ejected material is likely to have exceeded 10^-4 solar mass.