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Published April 2023 | Published
Journal Article Open

A survey for variable young stars with small telescopes: VI – Analysis of the outbursting Be stars NSW 284, gaia 19eyy, and VES 263


This paper is one in a series reporting results from small telescope observations of variable young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared, and mid-infrared photometry for all three objects, along with follow-up spectra for two of the three. The sources are characterized as rare, truly regularly outbursting Be stars. We interpret the photometric data within a framework for modelling light-curve morphology, and find that the models correctly predict the burst shapes, including their larger amplitudes and later peaks towards longer wavelengths. We are thus able to infer the start and end times of mass loading into the circumstellar discs of these stars. The disc sizes are typically 3 – 6 times the areas of the central star. The disc temperatures are ∼40 per cent, and the disc luminosities are ∼10 per cent of those of the central Be star, respectively. The available spectroscopy is consistent with inside-out evolution of the disc. Higher excitation lines have larger velocity widths in their double-horned shaped emission profiles. Our observations and analysis support the decretion disc model for outbursting Be stars.

Additional Information

© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Our referee is acknowledged for a helpful report. We would like to thank all contributors of optical photometric data for their efforts towards the success of the HOYS project. We also thank the entire Gattini-IR team for access to infrared photometry of our sources. We acknowledge Tony Rodriguez for assistance in acquiring and reducing the Palomar/DoubleSpec data for NSW 284 that is reported here, and Adolfo Carvalho for assistance with DIBs feature identification in the HIRES spectra. JCW was funded by the European Union (ERC − European Research Council, 101039452). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. All authors from Silesian University of Technology were responsible for data processing and automation of observations at SUTO observatories and were financed by grant BK-246/RAu-11/2022. Piotr Jóźwik-Wabik also acknowledges support from grant BKM-574/RAu-11/2022 and 32/014/SDU/10-22-20. DATA AVAILABILITY STATEMENT. Some of the photometry data underlying this article are available in the HOYS data base at http://astro.kent.ac.uk/HOYS-CAPS/. Some of the spectroscopic data are available in the Keck Observatory Archive (KOA).

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August 22, 2023
August 22, 2023