YETI follow-up observations of the T Tauri star CVSO30 with transit-like dips

TL;DR

This study presents seven years of optical monitoring data of the T Tauri star CVSO30, analyzing the evolution of its variable light curve and proposing orbiting gas clouds as the most plausible explanation for the observed dips.

Contribution

It provides a long-term observational analysis of CVSO30's light curve and evaluates different scenarios, favoring orbiting gas clouds as the cause of variability.

Findings

Dimming events evolved significantly since 2014.

Orbiting gas clouds at a Keplerian radius best explain the variability.

The star's light curve shows complex, changing transit-like dips.

Abstract

The T Tauri star CVSO30, also known as PTFO8-8695, was studied intensively with ground based telescopes as well as with satellites over the last decade. It showed a variable light curve with additional repeating planetary transit-like dips every ~0.8h. However, these dimming events changed in depth and duration since their discovery and from autumn 2018 on, they were not even present or near the predicted observing times. As reason for the detected dips and their changes within the complex light curve, e.g. a disintegrating planet, a circumstellar dust clump, stellar spots, possible multiplicity and orbiting clouds at a Keplerian co-rotating radius were discussed and are still under debate. In this paper, we present additional optical monitoring of CVSO30 with the meter class telescopes of the Young Exoplanet Transit Initiative in Asia and Europe over the last seven years and characterize CVSO30 with the new Early Data Release 3 of the ESA Gaia Mission. As a result, we describe the evolution of the dimming events in the optical wavelength range since 2014 and present explanatory approaches for the observed variabilities. We conclude that orbiting clouds of gas at a Keplerian co-rotating radius are the most promising scenario to explain most changes in CVSO30's light curve.