The Orbit and Dynamical Mass of Polaris: Observations with the CHARA Array

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dc.contributor.authorEvans, Nancy Remage
dc.contributor.authorSchaefer, Gail H.
dc.contributor.authorGallenne, Alexandre
dc.contributor.authorTorres, Guillermo
dc.contributor.authorHorch, Elliott P.
dc.contributor.authorAnderson, Richard I.
dc.contributor.authorMonnier, John D.
dc.contributor.authorRoettenbacher, Rachael M.
dc.contributor.authorBaron, Fabien
dc.contributor.authorAnugu, Narsireddy
dc.contributor.authorDavidson, James W.
dc.contributor.authorKervella, Pierre
dc.contributor.authorBras, Garance
dc.contributor.authorProffitt, Charles
dc.contributor.authorMérand, Antoine
dc.contributor.authorKarovska, Margarita
dc.contributor.authorJones, Jeremy
dc.contributor.authorLanthermann, Cyprien
dc.contributor.authorKraus, Stefan
dc.contributor.authorCodron, Isabelle
dc.contributor.authorBond, Howard E.
dc.contributor.authorViviani, Giordano
dc.date.accessioned2024-09-17T13:44:05Z
dc.date.available2024-09-17T13:44:05Z
dc.date.issued2024-08
dc.descriptionIndexación: Scopus.
dc.description.abstractThe 30 yr orbit of the Cepheid Polaris has been followed with observations by the Center for High Angular Resolution Astronomy (CHARA) Array from 2016 through 2021. An additional measurement has been made with speckle interferometry at the Apache Point Observatory. Detection of the companion is complicated by its comparative faintness—an extreme flux ratio. Angular diameter measurements appear to show some variation with pulsation phase. Astrometric positions of the companion were measured with a custom grid-based model-fitting procedure and confirmed with the CANDID software. These positions were combined with the extensive radial velocities (RVs) discussed by Torres to fit an orbit. Because of the imbalance of the sizes of the astrometry and RV data sets, several methods of weighting are discussed. The resulting mass of the Cepheid is 5.13 ± 0.28 M ⊙. Because of the comparatively large eccentricity of the orbit (0.63), the mass derived is sensitive to the value found for the eccentricity. The mass combined with the distance shows that the Cepheid is more luminous than predicted for this mass from evolutionary tracks. The identification of surface spots is discussed. This would give credence to the identification of a radial velocity variation with a period of approximately 120 days as a rotation period. Polaris has some unusual properties (rapid period change, a phase jump, variable amplitude, and unusual polarization). However, a pulsation scenario involving pulsation mode, orbital periastron passage, and low pulsation amplitude can explain these characteristics within the framework of pulsation seen in Cepheids.
dc.description.urihttps://www-scopus-com.recursosbiblioteca.unab.cl/record/display.uri?eid=2-s2.0-85201702806&origin=resultslist&sort=plf-f&src=s&sid=10772d8bae0a069cf56df862026d7f3b&sot=aff&sdt=cl&cluster=scosubjabbr%2C%22PHYS%22%2Ct%2C%22EART%22%2Ct%2Bscosubtype%2C%22ar%22%2Ct%2Bscofreetoread%2C%22all%22%2Ct&s=AF-ID%2860002636%29+AND+SUBJAREA%28PHYS%29&sl=34&sessionSearchId=10772d8bae0a069cf56df862026d7f3b&relpos=9
dc.identifier.citationAstrophysical Journal Open Access Volume 971, Issue 21 August 2024 Article number 190
dc.identifier.doi10.3847/1538-4357/ad5e7a
dc.identifier.issn0004637X
dc.identifier.urihttps://repositorio.unab.cl/handle/ria/60248
dc.language.isoen
dc.publisherInstitute of Physics
dc.rights.licenseCC BY 4.0 Attribution 4.0 International
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectVariable Star
dc.subjectMagellanic Clouds
dc.subjectPhotometry
dc.titleThe Orbit and Dynamical Mass of Polaris: Observations with the CHARA Array
dc.typeArtículo
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