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

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.

Multicolor Variability of Young Stars in the Lagoon Nebula: Driving Causes and Intrinsic Timescales

“…The accelerated gas in magnetospheric accretion funnels are also associated with distinctive spectroscopic signatures such as Hα line emission (e.g., White & Basri 2003;Kurosawa et al 2006). Observations in the optical, sensitive to the photospheric emission from the central star, allow us to reconstruct any modulation effects by surface features (e.g., Bouvier et al 1995;Grankin et al 2008) or circumstellar structures (e.g., Bouvier et al 2007;Fonseca et al 2014;Frasca et al 2020). Finally, infrared (IR) wavelengths trace the thermal emission produced by dust at different locations within the disk, from the inner AU (near-IR; e.g., Robberto et al 2010;Roquette et al 2020), to radii of few AU (mid-IR; e.g., Oliveira & van Loon 2004;Günther et al 2014) to tens of AU (far-IR; e.g., Fedele et al 2013;Alonso-Martínez et al 2017).…”

Monitoring accretion rate variability in the Orion Nebula Cluster with the Wendelstein Wide Field Imager

“…The accretion rate variability manifests itself mainly in the optical and near-UV bands (e.g., Venuti et al 2014Venuti et al , 2015Robinson & Espaillat 2019;Schneider et al 2020). The observed brightness variations stem from a multitude of mechanisms, including accretion bursts (e.g., Venuti et al 2014), inner disk warps (e.g., Frasca et al 2020), accretion columns creating hot spots (e.g., Cody et al 2014) moving in and out of view while the YSO rotates (e.g., Cody & Hillenbrand 2018;Schneider et al 2020) and phases of stable or unstable accretion regimes (e.g., Sousa et al 2016).…”

A Population of Dipper Stars from the Transiting Exoplanet Survey Satellite Mission

“…Moulton (2020) provides an in-depth review of dipper star detections and their corresponding catalogs. Dipper stars are generally members of young associations and have been detected within a number of young comoving systems, including ρ Ophiuchus (1 Myr) (e.g., Ansdell et al 2016); the Orion Nebula Cluster (1-3 Myr) (e.g., Morales-Calderón et al 2011;Moulton 2020;Tajiri et al 2020, Moulton et al 2022; the Lagoon nebula (1-3 Myr); the Lupus region (1-3 Myr) (e.g., Bredall et al 2020;Nardiello 2020); the Taurus association (3 Myr) (e.g., Rodriguez et al 2017;Rebull et al 2020;Roggero et al 2021); the open cluster NGC 2264 (3 Myr) (e.g., Alencar et al 2010;Cody et al 2014); γ Velorum (3-4 Myr) (Nardiello 2020); Chamaeleon I and II (both 3 Myr) (e.g., Frasca et al 2020;Nardiello 2020); Upper Scorpius (5-10 Myr) (e.g., Ansdell et al 2016;Cody & Hillenbrand 2018;Tajiri et al 2020); and the Corona Australis association (<10 Myr) (Nardiello 2020).…”