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Short and long term near-infrared spectroscopic variability of eruptive protostars from VVV

Guo, Zhen, Lucas, P.W., Contreras Peña, C., Kurtev, R.G., Smith, L.C., Borissova, J., Alonso-García, J., Minniti, D., Caratti o Garatti, A., Froebrich, D. and others. (2019) Short and long term near-infrared spectroscopic variability of eruptive protostars from VVV. Monthly Notices of the Royal Astronomical Society, 429 (1). pp. 294-314. ISSN 1365-2966. (doi:10.1093/mnras/stz3374)

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https://dx.doi.org/10.1093/mnras/stz3374

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 H2-emitting YSOs show significant but modest variation, and 2/6 sources have large variations in Brγ. Over year-long timescales, 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 timescales. Two objects show signs of on/off magnetospheric accretion traced by Brγ emission. In addition, a 60% inter-night brightening of the H2 outflow is detected in one YSO.

Item Type: Article
DOI/Identification number: 10.1093/mnras/stz3374
Uncontrolled keywords: Centre for Astrophysics and Planetary Sciences, Astrophysics, Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Dirk Froebrich
Date Deposited: 04 Dec 2019 16:03 UTC
Last Modified: 04 Feb 2020 16:19 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/79144 (The current URI for this page, for reference purposes)
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