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The SMC B-type supergiant AzV322: a g-mode pulsator with a circumstellar disc

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cris.lastimport.scopus2024-02-12T19:40:44Z
dc.abstract.enWe present a photometric and spectroscopic study of AzV322, an emission line object located in the Small Magellanic Cloud previously classified between O9 and B0. We analyse 17.5 yr of I- and V-band OGLE-II, -III and -IV light curves and find four significant frequencies, viz. f<SUB>1</SUB> = 0.386 549 ± 0.000 003, f<SUB>2</SUB> = 0.101 177 ± 0.000 005, f<SUB>3</SUB> = 0.487 726 ± 0.000 015 and f<SUB>4</SUB> = 0.874 302 ± 0.000 020 cycles d<SUP>-1</SUP> . The f<SUB>1</SUB> frequency (period 2.587 00 ± 0.000 02 d) provides the stronger periodogram peak and gives a single wave light curve of full amplitude 0.066 mag in the I band. High-resolution optical spectroscopy confirms the early B-type spectral type and reveals prominent double peak Balmer, Paschen, O I 8446 and He I 5875 emissions. The spectral energy distribution shows significant colour excess towards long wavelengths possibly attributed to free-free emission in a disc -like envelope. Our analysis yields T<SUB>eff</SUB> = 23 000 ± 1500 K, log g = 3.0 ± 0.5, M = 16 ± 1 M<SUB>⊙</SUB>, R = 31.0 ± 1.1 R<SUB>⊙</SUB> and L<SUB>bol</SUB> = 10<SUP>4.87 ± 0.06</SUP> L<SUB>⊙</SUB>. AzV322 might be a member of the new class of slowly pulsating B supergiants introduced by Saio et al. and documented by Lefever, Puls & Aerts; however its circumstellar disc makes it an hither to unique object. Furthermore, we notice that an O-C analysis for f<SUB>1</SUB> reveals quasi-cyclic changes for the times of maximum in a time-scale of 20 yr, which might indicate a light-travel time effect in a very wide orbit binary with an undetected stellar component.
dc.affiliationUniwersytet Warszawski
dc.contributor.authorMennickent, R. E.
dc.contributor.authorKołaczkowski, Z.
dc.contributor.authorSoszyński, Igor
dc.contributor.authorCabezas, M.
dc.contributor.authorGarrido, H. E.
dc.date.accessioned2024-01-26T10:47:43Z
dc.date.available2024-01-26T10:47:43Z
dc.date.copyright2017-10-06
dc.date.issued2018
dc.description.accesstimeBEFORE_PUBLICATION
dc.description.financeNie dotyczy
dc.description.number3
dc.description.versionORIGINAL_AUTHOR
dc.description.volume473
dc.identifier.doi10.1093/MNRAS/STX2612
dc.identifier.issn0035-8711
dc.identifier.urihttps://repozytorium.uw.edu.pl//handle/item/123140
dc.identifier.weblinkhttp://adsabs.harvard.edu/abs/2018MNRAS.473.4055M
dc.languageeng
dc.pbn.affiliationastronomy
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.relation.pages4055-4063
dc.rightsOther
dc.sciencecloudnosend
dc.titleThe SMC B-type supergiant AzV322: a g-mode pulsator with a circumstellar disc
dc.typeJournalArticle
dspace.entity.typePublication