The VMC survey - XXXVI. Young stellar variability in the Large Magellanic Cloud

Viktor Zivkov*, Joana M. Oliveira, Monika G. Petr-Gotzens, Stefano Rubele, Maria-Rosa L. Cioni, Jacco Th van Loon, Richard de Grijs, Jim Emerson, Valentin D. Ivanov, Marcella Marconi, Maria Ida Moretti, Vincenzo Ripepi, Florian Niederhofer, Ning Chen Sun

*Corresponding author for this work

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    Abstract

    Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibits photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present the first variability study of massive YSOs in an ∼ 1.5 deg2 region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC (∼ 0.4-0.5 Z) have an impact on the variability characteristics. Multi-epoch near-infrared (NIR) photometry was obtained from the VISTA Survey of the Magellanic Clouds (VMC) and our own monitoring campaign using the VISTA telescope. By applying a reduced χ2-analysis, stellar variability was identified. We found 3062 candidate variable stars from a population of 362 425 stars detected. Based on several Spitzer studies, we compiled a sample of high-reliability massive YSOs: a total of 173 massive YSOs have NIR counterparts (down to Ks ∼ 18.5 mag) in the VMC catalogue, of which 39 display significant (>3σ) variability. They have been classified as eruptive, fader, dipper, short-term variable, and long-period variable YSOs based mostly on the appearance of their Ks-band light curves. The majority of YSOs are aperiodic; only five YSOs exhibit periodic light curves. The observed amplitudes are comparable or smaller than those for Galactic YSOs (only two Magellanic YSOs exhibit ΔKs > 1 mag), not what would have been expected from the typically larger mass accretion rates observed in the Magellanic Clouds.

    Original languageEnglish
    Pages (from-to)458-486
    Number of pages29
    JournalMonthly Notices of the Royal Astronomical Society
    Volume494
    Issue number1
    DOIs
    Publication statusPublished - 1 May 2020

    Bibliographical note

    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 494, Issue 1, May 2020, Pages 458-486, https://doi.org/10.1093/mnras/staa626. Copyright 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

    Keywords

    • Galaxies: individual: LMC
    • Infrared: stars
    • Stars: pre-main-sequence
    • Stars: variables: general
    • Techniques: photometric

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