@article{440e6d71deaa4ebaa6ea4b01afa638b0,
title = "Short- and long-term near-infrared spectroscopic variability of eruptive protostars from VVV",
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 one-day and one-to-two-year intervals and analysed in combination with VVV light curves. CO overtone absorption features are observed on three objects with FUor-like spectra: all show deeper absorption when they are brighter. This implies stronger emission from the circumstellar discwith 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 Br? 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 one-day time-scale, 60 per cent of H2-emitting YSOs show significant but modest variation, and 2/6 sources have large variations in Brγ. Over year-long time-scales, H2 flux variations remain modest despite up to 1.8 mag variation in Ks. 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 time-scales. Two objects show signs of on/off magnetospheric accretion traced by Brγ emission. In addition, a 60 per cent inter-night brightening of the H2 outflow is detected in one YSO.",
keywords = "Herbig Ae/Be, Infrared: stars, Stars: pre-main sequence, Stars: protostars, Stars: variables: T Tauri",
author = "Zhen Guo and Lucas, {P. W.} and Pe{\~n}a, {C. Contreras} and Kurtev, {R. G.} and Smith, {L. C.} and J. Borissova and J. Alonso-Garcia and D. Minniti and Garatti, {A. Carattio} and D. Froebrich",
note = "Funding Information: ZG and PWL acknowledge support by Science and Technology Facilities Council (STFC) Consolidated Grants ST/R00905/1, ST/M001008/1 and ST/J001333/1 and the STFC Panel for the Allocation of Telescope Time (PATT)-linked grant ST/L001403/1. We thank the staff of the Magellan Telescopes and the European Southern Observatory for their work in operating the facilities used in this project. Funding Information: ZG and PWL acknowledge support by Science and Technology Facilities Council (STFC) Consolidated Grants ST/R00905/1, ST/M001008/1 and ST/J001333/1 and the STFC Panel for the Allocation of Telescope Time (PATT)-linked grant ST/L001403/1. We thank the staff of the Magellan Telescopes and the European Southern Observatory for their work in operating the facilities used in this project. We gratefully acknowledge data from the ESO Public Survey program ID 179.B-2002 taken with the VISTA telescope, and products from the Cambridge Astronomical Survey Unit (CASU). This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile during Chilean programes: CN2014A-16 and CN2015A-78. DM and JAG thank support from the BASAL Center for Astrophysics and Associated Technologies (CATA) through grant AFB170002 and Fondo Nacional de Desarrollo Cientifico y Tecnol?gico (FONDECYT) Regular grant No. 1170121. DM, JB, and RK thank support from the Ministry for the Economy, Development and Tourism, Programa Iniciativa Cientifica Milenio grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS). ACG acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 743029). The contribution of CCP was funded by a Leverhulme Trust Research Project Grant. Funding Information: ACG acknowledges funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement No. 743029). The contribution of CCP was funded by a Leverhulme Trust Research Project Grant. Funding Information: We gratefully acknowledge data from the ESO Public Survey program ID 179.B-2002 taken with the VISTA telescope, and products from the Cambridge Astronomical Survey Unit (CASU). This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile during Chilean programes: CN2014A-16 and CN2015A-78. DM and JAG thank support from the BASAL Center for Astrophysics and Associated Technologies (CATA) through grant AFB170002 and Fondo Nacional de Desarrollo Cientifico y Tecnol{\'o}gico (FONDE-CYT) Regular grant No. 1170121. DM, JB, and RK thank support from the Ministry for the Economy, Development and Tourism, Programa Iniciativa Cientifica Milenio grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS). Publisher Copyright: {\textcopyright} 2019 The Author(s).",
year = "2020",
month = feb,
day = "1",
doi = "10.1093/mnras/stz3374",
language = "English",
volume = "492",
pages = "294--314",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}