J/MNRAS/vol/page NIR variability of eruptive protostars (Guo+, 2019) ================================================================================ Short and long term near-infrared spectroscopic variability of eruptive protostars from VVV Zhen Guo, P. W. Lucas, C. Contreras Pena, R. G. Kurtev, L. C. Smith, J. Borissova, J. Alonso-Garcia, D. Minniti, A. Caratti o Garatti and D. Froebrich =2019MNRAS.VVV..pppI (SIMBAD/NED BibCode) ================================================================================ Keywords: stars: pre-main sequence -- stars: protostar -- stars: variables: T Tauri -- infrared: stars Abstract: Numerous eruptive variable young stellar objects (YSOs), mostly Class I systems, were recently detected by the near-infrared Vista Variables in the Via Lactea (VVV) survey. We present an exploratory near-infrared spectroscopic variability study of 14 eruptive YSOs. The variations were sampled over 1-day and 1 to 2-year intervals and analysed in combination with VVV light curves. CO overtone absorption features are observed on 3 objects with FUor-like spectra: all show deeper absorption when they are brighter. This implies stronger emission from the circumstellar disc with a steeper vertical temperature gradient when the accretion rate is higher. This confirms the nature of fast VVV FUor-like events, in line with the accepted picture for classical FUors. The absence of Brγ emission in a FUor-like object declining to pre-outburst brightness suggests that reconstruction of the stellar magnetic field is a slow process. Within the 1-day timescale, 60% of H_2-emitting YSOs show significant but modest variation, and 2/6 sources have large variations in Brγ. Over year-long timescales, H_2 flux variations remain modest despite up to 1.8 mag variation in K_s. This indicates that emission from the molecular outflow usually arises further from the protostar and is unaffected by relatively large changes in accretion rate on year-long timescales. Two objects show signs of on/off magnetospheric accretion traced by Brγ emission. In addition, a 60% inter-night brightening of the H_2 outflow is detected in one YSO. Description: The vvvlightcurve.dat file contains the K_s band VVV light curves of the 16 targets observed in this work. The light curves are generated by point spreadfunction (PSF) fitting photometry based on an updated version of DoPHOT (Schechter et al.1993; Alonso-Garcia et al. 2012). The light curves were drawnfrom a preliminary version of a full-time series and astrometric VVV catalogue (L. Smith et al., in prep) File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file vvvlightcurve.dat 30 800 VVV lightcurve of 16 eruptive objects -------------------------------------------------------------------------------- Byte-by-byte Description of file: vvvlightcurve.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 10 A10 - name Target name 11- 17 F7.1 d MJD Modified Julian Date 24- 30 F7.4 mag Kmag Ks band magnitude -------------------------------------------------------------------------------- Note -------------------------------------------------------------------------------- ================================================================================ (End) Zhen Guo [University of Hertfordshire] 29-Nov-2019