On the evolutionary state of massive stars in transition phases in M33

dc.creatorKourniotis, M.
dc.creatorKraus, M.
dc.creatorArias, María Laura
dc.creatorCidale, Lydia Sonia
dc.creatorTorres, Andrea Fabiana
dc.date2018-11
dc.date2020-04-16T22:55:40Z
dc.date.accessioned2023-07-14T19:18:46Z
dc.date.available2023-07-14T19:18:46Z
dc.identifierhttp://sedici.unlp.edu.ar/handle/10915/93616
dc.identifierhttps://academic.oup.com/mnras/article-abstract/480/3/3706/5063594
dc.identifierissn:0035-8711
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/7434818
dc.descriptionThe advanced stages of several high-mass stars are characterized by episodic mass-loss shed during phases of instability.Key for assigning these stars a proper evolutionary state is to assess the composition and geometry of their ejecta alongside the stellar properties. We selected five hot luminous blue variable candidates in M33 to refine their classification, investigate their circumstellar environments, and explore their evolutionary properties. Being accessible targets in the near-infrared, we conducted medium-resolution spectroscopy with GNIRS/GEMINI in the K-band to investigate their molecular circumstellar environments. Two stars were found to display CO emission, which was modelled to emerge from a circumstellar or circumbinary Keplerian disc/ring. The identification of the carbon isotope 13C and, for one of the two stars, a significantly low 12CO/13CO ratio, implies an evolved stellar state. As both CO emission stars are highly luminous and hence do not undergo a red supergiant phase, we suggest that stripping processes and equatorial high-density ejecta due to fast rotation are responsible for the enrichment of the stellar surface with processedmaterial from the core.Acandidate B[e]SG displays an absorption CO profile, which may be attributed to a jet or stellar pulsations. The featureless infrared spectra of two stars suggest a low-density gas shell or dissipation of the molecule due to the ionizing temperature of the star. We propose spectroscopic monitoring of our targets to evaluate the stability of the CO molecule and assess the time-dependent dynamics of the circumstellar gas structures.
dc.descriptionFacultad de Ciencias Astronómicas y Geofísicas
dc.descriptionInstituto de Astrofísica de La Plata
dc.formatapplication/pdf
dc.format3706-3717
dc.languageen
dc.rightshttp://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.rightsCreative Commons Attribution-NonCommercial-ShareAlike 2.5 Argentina (CC BY-NC-SA 2.5)
dc.subjectAstronomía
dc.subjectFísica
dc.subjectCiencias Naturales
dc.subjectCiencias Exactas
dc.subjectInfrared: stars
dc.subjectStars: massive
dc.subjectStars: winds, outflows
dc.subjectCircumstellar matter
dc.subjectStars: emission line, Be
dc.subjectSupergiants
dc.titleOn the evolutionary state of massive stars in transition phases in M33
dc.typeArticulo
dc.typePreprint


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