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

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

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 $\sim 1.5\, \mathrmdeg^2$ region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC ($\sim 0.4\!-\!0.5\, \mathrmZ_ødot $) 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 ?2-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 $K_s\sim 18.5\,$mag) in the VMC catalogue, of which 39 display significant (>3s) 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 $? K_s\gt 1\,$mag), not what would have been expected from the typically larger mass accretion rates observed in the Magellanic Clouds.

Citation

Zivkov, V., Oliveira, J. M., Petr-Gotzens, M. G., Rubele, S., Cioni, M. L., Van Loon, J. T., …Sun, N. (2020). The VMC survey – XXXVI. Young stellar variability in the Large Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 494(1), 458 -486. https://doi.org/10.1093/mnras/staa626

• Journal Article Type: Article
• Acceptance Date: Feb 21, 2020
• Online Publication Date: Mar 4, 2020
• Publication Date: 2020-05
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 494
• Issue: 1
• Pages: 458 -486
• DOI: https://doi.org/10.1093/mnras/staa626
• Keywords: techniques: photometric; stars: pre-main-sequence; stars: variables: general; galaxies: individual: LMC; infrared: stars
• Publisher URL: https://doi.org/10.1093/mnras/staa626