2026ApJ..1000L...5T -
Astrophys. J., 1000, L5 (2026/March-3)
Gaia-GIC-1: An Evolving Catastrophic Planetesimal Collision Candidate.
TZANIDAKIS A. and DAVENPORT J.R.A.
Abstract (from CDS):
We report the discovery of the optical dipper and low-luminosity infrared stellar transient Gaia20ehk (hereafter, Gaia-GIC-1), which is currently undergoing high-amplitude variability due to transiting dusty material. In this work, we identify Gaia-GIC-1 as a likely young F-type star based on the spectral energy distribution before the onset of the high-amplitude optical variability. We detect a significant periodic modulation of 380.5 days in Gaia G band before the onset of the infrared brightening, consistent with a ∼1.1 au orbit assuming circular orbits and a 1.3 M_⊙ _star. The system has remained in an infrared-bright state for >4 yr since the last near-infrared detection, confirmed by recent SPHEREx observations, while continuing to undergo large-amplitude irregular optical dimming. We measure the dust temperature from the freshly generated debris to be ∼900 K based on available Wide-field Infrared Survey Explorer photometry, and the dust clump size to have a minimum cross-sectional area of 0.13 au2, and the dust mass 4 × 1020 kg. Currently, optical follow-up spectroscopy has not revealed any prominent features in the system, likely due to its highly variable nature. We hypothesize that Gaia-GIC-1 represents debris recently formed in a planetary collision, which produced a clumpy dust cloud on a bound orbit, producing the observed dimming events. The ongoing collisional activity in this system presents a unique opportunity for understanding terrestrial planet formation.
Abstract Copyright:
© 2026. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Circumstellar dust - Irregular variable stars
Simbad objects:
6
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