EXORCISM: a spectroscopic survey of young eruptive variables (EXor and candidates)

Abstract

We present an optical/near-IR survey of 11 variable young stars (EXors and EXor candidates) aimed at deriving and monitoring their accretion properties. About 30 optical and near-infrared spectra ($\Re$ $\sim$ 1500-2000) were collected between 2014-2019 with the Large Binocular Telescope (LBT). From the spectral analysis we have derived the accretion luminosity and mass accretion rate, the visual extinction, the temperature and density of the permitted line formation region, and the signature of the outflowing matter. Two sources (ASASSN-13db and iPTF15afq) have been observed in outburst and quiescence, three during a high-level of brightness (XZ Tau, PV Cep, and NY Ori), and the others in quiescence. These latter have accretion luminosity and mass accretion rates in line with the values measured in classical T Tauri stars of similar mass. All sources observed more than once present accretion variability. The most extreme case is ASASSN-13db, for which the mass accretion rate decreases by two orders of magnitude from the outburst peak in 2015 to quiescence in 2017. Also, in NY Ori the accretion luminosity decreases by a factor 25 in one year. In 80% of the sample we detect the [OI]630 nm line, a tracer of mass loss. From the variability of the H$\alpha$/[OI]630, ratio, we conclude that mass accretion variations are larger than mass loss variations. From the analysis of the HI recombination lines a correlation is suggested between the density of the line formation region and the level of accretion activity of the source.

To appear in ApJ

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Cited by in corpus (9)

• Diagnosing FUor-like Sources: The Parameter Space of Viscously Heated Disks in the Optical and Near-IR
• Photometric and spectroscopic study of the EXor-like eruptive young star Gaia19fct
• The most variable VVV sources: eruptive protostars, dipping giants in the Nuclear Disc and others
• Young stellar objects, accretion disks, and their variability with Rubin Observatory LSST
• Accretion and extinction variations in the low-mass pre-main sequence binary system WX Cha
• Resolving the Binary Components of the Outbursting Protostar HBC 494 with ALMA
• The Enigma of Gaia18cjb: a Rare Hybrid of FUor and EXor?
• Short- and long-term variations of the high mass accretion rate classical T Tauri star DR Tau
• Two epoch spectra-imagery of PV Cep outflow system