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Title: Discovery of a mid-infrared protostellar outburst of exceptional amplitude
Authors: Lucas, P. W.
Elias, J.
Points, S.
Guo, Z.
Smith, L. C.
Stecklum, B.
Vorobyov, E.
Morris, C.
Borissova, J.
Kurtev, R.
Contreras, Peña, C.
Medina, N.
Minniti, D.
Ivanov, V. D.
Saito, R. K.
Issue Date: 2020
Publisher: Oxford University Press
Citation: Discovery of a mid-infrared protostellar outburst of exceptional amplitude / P. W. Lucas, J. Elias, S. Points, et al. — DOI 10.1093/mnras/staa2915 // Monthly Notices of the Royal Astronomical Society. — 2020. — Vol. 499. — Iss. 2. — P. 1805-1822.
Abstract: We report the discovery of a mid-infrared outburst in a young stellar object (YSO) with an amplitude close to 8 mag at λ ≈ 4.6 μm. WISEA J142238.82-611553.7 is one of 23 highly variable Wide-field Infrared Survey Explorer (WISE) sources discovered in a search of infrared dark clouds (IRDCs). It lies within the small IRDC G313.671-0.309 (d ≈ 2.6 kpc), seen by the Herschel/Hi-Gal survey as a compact massive cloud core that may have been measurably warmed by the event. Pre-outburst data from Spitzer in 2004 suggest it is a class I YSO, a view supported by observation of weak 2.12 μm H2 emission in an otherwise featureless red continuum spectrum in 2019 (6 mag below the peak in Ks). Spitzer, WISE, and VISTA Variables in the Via Lactea (VVV) data show that the outburst began by 2006 and has a duration >13 yr, with a fairly flat peak from 2010 to 2014. The low pre-outburst luminosity implies a low-mass progenitor. The outburst luminosity of a few × 102 L⊙ is consistent with an accretion rate M ≈ 10-4 M⊙yr-1, comparable to a classical FU Orionis event. The 4.6 μm peak in 2010 implies T = 800-1000 K and a disc radial location R ≈ 4.5 au for the emitting region. The colour evolution suggests subsequent progression outwards. The apparent absence of the hotter matter expected in thermal instability or MRI models may be due to complete obscuration of the innermost disc, e.g. by an edge-on disc view. Alternatively, disc fragmentation/infalling fragment models might more naturally explain a mid-infrared peak, though this is not yet clear. © 2020 The Author(s).
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85096895600
PURE ID: 20140674
ISSN: 358711
DOI: 10.1093/mnras/staa2915
metadata.dc.description.sponsorship: We thank the referee for reading the paper and encouraging us to provide more detail in several places. This publication makes use of data products from the WISE satellite, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration (NASA). The work is based in part on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Minist?rio da Ci?ncia, Tecnologia e Inova??es (MCTI) do Brasil, the US National Science Foundation's National Optical-Infrared Astronomy Research Laboratory (NOIRLab), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
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