# Multi-Color Simultaneous Photometry of the T-Tauri Star Having A Planetary Candidate CVSO 30

## TL;DR

This study presents simultaneous multi-band photometry of the T-Tauri star CVSO 30, revealing wavelength-dependent fading depths that suggest dust or hotspot occultation rather than a planetary atmosphere or gravity darkening.

## Contribution

First simultaneous multi-band observations of CVSO 30 showing significant wavelength dependence of fading depths, challenging planetary atmosphere explanations.

## Key findings

- Wavelength dependence of fading depths observed: 3.1%, 1.7%, 1.0%.
- Cloudless hot Jupiter atmosphere cannot explain the large wavelength dependence.
- Fading likely caused by circumstellar dust or hotspot occultation.

## Abstract

We present three-band simultaneous observations of a weak-line T-Tauri star CVSO~30 (PTFO~8-8695), which is one of the youngest objects having a candidate transiting planet. The data were obtained with the Multicolor Simultaneous Camera for studying Atmospheres of Transiting exoplanets (MuSCAT) on the 188 cm telescope at Okayama Astrophysical Observatory in Japan. We observed the fading event in the $g^{\prime}_2$-, $r^{\prime}_2$-, and $z_{\rm s,2}$-bands simultaneously. As a result, we find a significant wavelength dependence of fading depths of about 3.1\%, 1.7\%, 1.0\% for the $g^{\prime}_2$-, $r^{\prime}_2$-, and $z_{\rm s,2}$-bands, respectively. A cloudless H/He dominant atmosphere of a hot Jupiter cannot explain this large wavelength dependence. Additionally, we rule out a scenario by the occultation of the gravity-darkened host star. Thus our result is in favor of the fading origin as circumstellar dust clump or occultation of an accretion hotspot.