Letter to the Editor

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

¹ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
e-mail: antonio.frasca@inaf.it
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
³ INAF – Osservatorio Astronomico di Capodimonte, Via Moiariello, 16, 80131 Napoli, Italy
⁴ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone, Italy
⁵ NASA Ames Research Center, Moffett Blvd, Mountain View, CA 94035, USA
⁶ INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁷ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁸ Institut für Astronomie und Astrophysik, Eberhard-Karls Universität Tübingen, Sand 1, 72076 Tübingen, Germany
⁹ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

Received: 13 April 2020
Accepted: 29 June 2020

Abstract

We report the discovery of periodic dips in the multiband light curve of ISO-ChaI 52, a young stellar object in the Chamaeleon I dark cloud. This is one of the peculiar objects that display very low or negligible accretion 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 spectrum obtained at the Very Large Telescope with the X-shooter spectrograph with the tool ROTFIT to determine the stellar parameters. The latter, along with photometry from our campaign with the Rapid Eye Mount 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. Based on the rotational period of the star-disk system of 3.45 days, we estimate a disk inclination of 36°. 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 extinction as in the interstellar medium provides a better fit to the data.