ISO-ChaI 52: a weakly-accreting young stellar object with a dipper light curve

TL;DR

This paper reports the discovery of periodic light dips in ISO-ChaI 52, a young star with a circumstellar disk, revealing complex disk structures and low accretion activity through multi-band observations and modeling.

Contribution

It presents the first detailed analysis of periodic dips in ISO-ChaI 52, combining spectral and photometric data to model disk warp structures and their extinction properties.

Findings

Periodic dips with a 3.45-day period were observed.

A two-component disk warp model explains the extinction behavior.

The star exhibits very low accretion despite having a thick circumstellar disk.

Abstract

We report on the discovery of periodic dips in the multiband lightcurve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one among the peculiar objects that display very low or negligible accretion both in their UV continuum and spectral lines, although they present a remarkable infrared excess emission characteristic of optically-thick circumstellar disks. We have analyzed a VLT/X-Shooter spectrum with the tool ROTFIT to determine the stellar parameters. The latter, along with photometry from our campaign with the REM telescope and from the literature, have allowed us to model the spectral energy distribution and to estimate the size and temperature of the inner and outer disk. From the rotational period of the star/disk system of 3.45 days we estimate a disk inclination of 36$^\circ$. The depth of the dips in different bands has been used to gain information about the occulting material. A single extinction law is not able to fit the observed behavior, while a two-component model of a disk warp composed of a dense region with a gray extinction and an upper layer with an ISM-type extinction provides a better fit of the data.