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An investigation of the photometric variability of confirmed and candidate Galactic Be stars using ASAS-3 data

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BERNHARD Klaus OTERO Sebastian HUMMERICH Stefan KALTCHEVA Nadia PAUNZEN Ernst BOHLSEN Terry

Rok publikování 2018
Druh Článek v odborném periodiku
Časopis / Zdroj Monthly Notices of the Royal Astronomical Society
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.1093/mnras/sty1320
Klíčová slova stars: circumstellar matter; Stars: early-type; stars: emission-line Be; stars: oscillations; stars: variables: general
Popis We present an investigation of a large sample of confirmed (N = 233) and candidate (N = 54) Galactic classical Be stars (mean V magnitude range of 6.4-12.6 mag), with the main aim of characterizing their photometric variability. Our sample stars were preselected among early-type variables using light-curve morphology criteria. Spectroscopic information was gleaned from the literature, and archival and newly acquired spectra. Photometric variability was analysed using archival ASAS-3 time-series data. To enable a comparison of results, we have largely adopted the methodology of Labadie-Bartz et al. (2017), who carried out a similar investigation based on KELT data. Complex photometric variations were established in most stars: outbursts on different time-scales (in 73 +/- 5 per cent of stars), long-term variations (36 +/- 6 per cent), periodic variations on intermediate time-scales (1 +/- 1 per cent), and short-term periodic variations (6 +/- 3 per cent). 24 +/- 6 per cent of the outbursting stars exhibit (semi) periodic outbursts. We close the apparent void of rare outbursters reported by Labadie-Bartz et al. (2017) and show that Be stars with infrequent outbursts are not rare. While we do not find a significant difference in the percentage of stars showing outbursts among early-type, mid-type, and late-type Be stars, we show that early-type Be stars exhibit much more frequent outbursts. We have measured rising and falling times for well-covered and well-defined outbursts. Nearly all outburst events are characterized by falling times that exceed the rising times. No differences were found between early-, mid-, and late-type stars; a single non-linear function adequately describes the ratio of falling time to rising time across all spectral subtypes, with the ratio being larger for short events.
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