Correlation and variability of the HeI 4471 and MgII 4481 absorption lines in Be stars: A possible diagnostic tool for nonradial pulsations

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dc.contributor.authorVogt, Nikolaus
dc.contributor.authorBarrera, Luis H.
dc.contributor.authorNavarro, Mario
dc.date.accessioned2019-12-28T02:45:11Z
dc.date.available2019-12-28T02:45:11Z
dc.date.issued1990
dc.description.abstractIn a total of 181 photographic spectrograms, obtained at the Manuel Foster Observatory of the Catholic University in Santiago (Chile), the equivalent widths of the absorption lines HeI 4471 and MgII 4481 have been determined for 10 selected southern Be stars and 4 normal B-type stars. The mean equivalent widths of each star are compared to published mean values from largers samples of B stars. On the average, Be stars coincide with normal B-type stars in their equivalent width. However, a striking difference between rapidly and slowly rotating stars in their line ratios (HeI/MgII) was found, which is probably an artifact due to a systematic misclassification of spectral types of rapidly rotating B stars (v sini>200 km s?1). Six of the ten Be stars show evidence for variability in HeI and/or MgII with time-scales shorter than a few days and amplitudes up to a factor 2 in equivalent width. Line variability occurs in the entire range of projected rotation velocity (70 km s?1<v sini<350 km s?1), but seems to be restricted to spectral types B2-B4. In addition, variations at longer time-scales (years) were observed in two cases. Three of the variable stars (HR 4074, HR 4537, and ? Ara) present correlated variations in both lines, one (? Cen) anti-correlated variability. We interpret our results in terms of nonradial pulsations and stress the importance to study the HeI/MgII lines and their variability in a larger sample of Be, Bn, and normal B stars, including archival material in order to follow-up line variability for several decades in the past.
dc.format.extent12 páginas
dc.fuente.origenSpringer
dc.identifier.doi10.1007/BF00642569
dc.identifier.urihttps://doi.org/10.1007/BF00642569
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/27056
dc.issue.numeroNo. 1
dc.language.isoen
dc.nota.accesoContenido parcial
dc.pagina.final156
dc.pagina.inicio145
dc.revistaAstrophysics and Space Sciencees_ES
dc.rightsacceso restringido
dc.subjectDiagnostic Tooles_ES
dc.subjectEntire Rangees_ES
dc.subjectAbsorption Linees_ES
dc.subjectRotation Velocityes_ES
dc.subjectStriking Differencees_ES
dc.subject.ddc520
dc.subject.deweyAstronomíaes_ES
dc.titleCorrelation and variability of the HeI 4471 and MgII 4481 absorption lines in Be stars: A possible diagnostic tool for nonradial pulsationses_ES
dc.typeartículo
dc.volumenVol. 173
sipa.codpersvinculados100456
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