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Strong Variability in AzV 493, an Extreme Oe-type Star in the SMC

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dc.abstract.enWe present 18 yr of OGLE photometry together with spectra obtained over 12 yr revealing that the early Oe star AzV 493 shows strong photometric (ΔI < 1.2 mag) and spectroscopic variability with a dominant, 14.6 yr pattern and ~40 day oscillations. We estimate the stellar parameters T <SUB>eff</SUB> = 42,000 K, $mathrm{log}L/{L}_{odot }=5.83pm 0.15$ , M/M <SUB>⊙</SUB> = 50 ± 9, and v sin i = 370 ± 40 km s<SUP>-1</SUP>. Direct spectroscopic evidence shows episodes of both gas ejection and infall. There is no X-ray detection, and it is likely a runaway star. The star AzV 493 may have an unseen companion on a highly eccentric (e > 0.93) orbit. We propose that close interaction at periastron excites ejection of the decretion disk, whose variable emission-line spectrum suggests separate inner and outer components, with an optically thick outer component obscuring both the stellar photosphere and the emission-line spectrum of the inner disk at early phases in the photometric cycle. It is plausible that AzV 493's mass and rotation have been enhanced by binary interaction followed by the core-collapse supernova explosion of the companion, which now could be either a black hole or a neutron star. This system in the Small Magellanic Cloud can potentially shed light on OBe decretion disk formation and evolution, massive binary evolution, and compact binary progenitors.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorOey, M. S.
dc.contributor.authorCastro, N.
dc.contributor.authorRenzo, M.
dc.contributor.authorVargas-Salazar, I.
dc.contributor.authorSuffak, M. W.
dc.contributor.authorRatajczak, Milena
dc.contributor.authorMonnier, J. D.
dc.contributor.authorSzymański, Michał
dc.contributor.authorPhillips, G. D.
dc.contributor.authorCalvet, N.
dc.contributor.authorChiti, A.
dc.contributor.authorMicheva, G.
dc.contributor.authorRasmussen, K. C.
dc.contributor.authorTownsend, R. H. D.
dc.date.accessioned2024-01-26T08:21:04Z
dc.date.available2024-01-26T08:21:04Z
dc.date.copyright2023-04-14
dc.date.issued2023
dc.description.accesstimeAT_PUBLICATION
dc.description.financePublikacja bezkosztowa
dc.description.number1
dc.description.versionFINAL_PUBLISHED
dc.description.volume947
dc.identifier.doi10.3847/1538-4357/ACB690
dc.identifier.issn0004-637X
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/120861
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2023ApJ...947...27O
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofAstrophysical Journal
dc.relation.pages27
dc.rightsCC-BY
dc.sciencecloudnosend
dc.titleStrong Variability in AzV 493, an Extreme Oe-type Star in the SMC
dc.typeJournalArticle
dspace.entity.typePublication