Bona fide, strong-variable galactic luminous blue variable stars are fast rotators: Detection of a high rotational velocity in HR Carinae

dc.creatorGroh, J. H.
dc.creatorDamineli, A.
dc.creatorHillier, D. J.
dc.creatorBarbá, Rodolfo Héctor
dc.creatorFernández Lajús, Eduardo
dc.creatorGamen, Roberto Claudio
dc.creatorMoisés, A. P.
dc.creatorSolivella, Gladys Rebeca
dc.creatorTeodoro, M.
dc.date2009
dc.date2019-10-04T16:05:11Z
dc.identifierhttp://sedici.unlp.edu.ar/handle/10915/82740
dc.identifierissn:0004-637X
dc.descriptionWe report optical observations of the luminous blue variable (LBV) HR Carinae which show that the star has reached a visual minimum phase in 2009. More importantly, we detected absorptions due to SiIV λλ4088-4116. To match their observed line profiles from 2009 May, a high rotational velocity of v rot ≃ 150 ∼ 20 km s<SUP>-1</SUP> is needed (assuming an inclination angle of 30°), implying that HR Car rotates at ≃0.88 ∼ 0.2 of its critical velocity for breakup (v<SUB>crit</SUB>). Our results suggest that fast rotation is typical in all strong-variable, bona fide galactic LBVs, which present S-Dor-type variability. Strong-variable LBVs are located in a well-defined region of the HR diagram during visual minimum (the "LBV minimum instability strip"). We suggest this region corresponds to where v crit is reached. To the left of this strip, a forbidden zone with v<SUB>rot</SUB>/v<SUB>crit</SUB>>1 is present, explaining why no LBVs are detected in this zone. Since dormant/ex LBVs like P Cygni and HD 168625 have low v rot, we propose that LBVs can be separated into two groups: fast-rotating, strong-variable stars showing S-Dor cycles (such as AG Car and HR Car) and slow-rotating stars with much less variability (such as P Cygni and HD 168625). We speculate that supernova (SN) progenitors which had S-Dor cycles before exploding (such as in SN 2001ig, SN 2003bg, and SN 2005gj) could have been fast rotators. We suggest that the potential difficulty of fast-rotating Galactic LBVs to lose angular momentum is additional evidence that such stars could explode during the LBV phase.
dc.descriptionInstituto de Astrofísica de La Plata
dc.descriptionFacultad de Ciencias Astronómicas y Geofísicas
dc.formatapplication/pdf
dc.formatL25-L30
dc.languageen
dc.rightshttp://creativecommons.org/licenses/by-nc-sa/4.0/
dc.rightsCreative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
dc.subjectCiencias Astronómicas
dc.subjectStars: atmospheres
dc.subjectStars: individual (HR Carinae)
dc.subjectStars: mass loss
dc.subjectStars: rotation
dc.subjectStars: variables: other
dc.subjectSupergiants
dc.titleBona fide, strong-variable galactic luminous blue variable stars are fast rotators: Detection of a high rotational velocity in HR Carinae
dc.typeArticulo
dc.typeArticulo


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