Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1

TL;DR

This study uses 877 days of Spitzer Space Telescope data combined with decades of optical and infrared observations to analyze dust production events in the extreme debris disc of TYC 4209-1322-1, revealing variability linked to giant collisions near 0.3 au.

Contribution

It provides the first long-term, gap-free mid-infrared monitoring of an extreme debris disc, linking observed variability to recent giant collision events and suggesting a chain of impact-driven dust production.

Findings

Disc showed significant brightening and fading between 2014-2018.

Detected a ~39-day flux modulation indicating ongoing collisional activity.

Evidence suggests multiple large impacts over the past 40 years.

Abstract

Extreme debris discs are characterized by unusually strong mid-infrared excess emission, which often proves to be variable. The warm dust in these discs is of transient nature and is likely related to a recent giant collision occurring close to the star in the terrestrial region. Here we present the results of a 877 days long, gap-free photometric monitoring performed by the Spitzer Space Telescope of the recently discovered extreme debris disc around TYC 4209-1322-1. By combining these observations with other time-domain optical and mid-infrared data, we explore the disc variability of the last four decades with particular emphasis on the last 12 yr. During the latter interval the disc showed substantial changes, the most significant was the brightening and subsequent fading between 2014 and 2018 as outlined in WISE data. The Spitzer light curves outline the fading phase and a subsequent new brightening of the disc after 2018, revealing an additional flux modulation with a period of ~39 days on top of the long-term trend. We found that all these variations can be interpreted as the outcome of a giant collision that happened at an orbital radius of ~0.3 au sometime in 2014. Our analysis implies that a collision on a similar scale could have taken place around 2010, too. The fact that the disc was already peculiarly dust rich 40 yr ago, as implied by IRAS data, suggests that these dust production events belong to a chain of large impacts triggered by an earlier even more catastrophic collision.