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dc.contributor.author
Silvotti, R.  
dc.contributor.author
Østensen, R. H.  
dc.contributor.author
Bloemen, S.  
dc.contributor.author
Telting, J. H.  
dc.contributor.author
Heber, U.  
dc.contributor.author
Oreiro, R.  
dc.contributor.author
Reed, M. D.  
dc.contributor.author
Farris, L. E.  
dc.contributor.author
O’Toole, S. J.  
dc.contributor.author
Lanteri, L.  
dc.contributor.author
Degroote, P.  
dc.contributor.author
Hu, H.  
dc.contributor.author
Baran, A. S.  
dc.contributor.author
Hermes, J. J.  
dc.contributor.author
Althaus, Leandro Gabriel  
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Marsh, T. R.  
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Charpinet, S.  
dc.contributor.author
Li, J.  
dc.contributor.author
Morris, R. L.  
dc.contributor.author
Sanderfer, D. T.  
dc.date.available
2016-12-28T14:28:59Z  
dc.date.issued
2012-08  
dc.identifier.citation
Silvotti, R.; Østensen, R. H. ; Bloemen, S.; Telting, J. H.; Heber, U.; et al.; Orbital properties of an unusually low-mass sdB star in a close binary system with a white dwarf; Oxford University Press; Monthly Notices Of The Royal Astronomical Society; 424; 8-2012; 1752-1761  
dc.identifier.issn
0035-8711  
dc.identifier.uri
http://hdl.handle.net/11336/10406  
dc.description.abstract
We have used 605 days of photometric data from the Kepler spacecraft to study KIC 6614501, a close binary system with an orbital period of 0.157 497 47(25) days (3.779 939 h), that consists of a low-mass subdwarf B (sdB) star and a white dwarf (WD). As seen in many other similar systems, the gravitational field of the WD produces an ellipsoidal deformation of the sdB which appears in the light curve as a modulation at two times the orbital frequency. The ellipsoidal deformation of the sdB implies that the system has a maximum inclination of ∼40°, with i ≈ 20° being the most likely. The orbital radial velocity (RV) of the sdB star is high enough to produce a Doppler beaming effect with an amplitude of 432 ± 5 ppm, clearly visible in the folded light curve. The photometric amplitude that we obtain, K1 = 85.8 km s−1, is ∼12 per cent less than the spectroscopic RV amplitude of 97.2 ± 2.0 km s−1. The discrepancy is due to the photometric contamination from a close object at about 5 arcsec north-west of KIC 6614501, which is difficult to remove. The atmospheric parameters of the sdB star, Teff = 23 700 ± 500 K and log g = 5.70 ± 0.10, imply that it is a rare object below the extreme horizontal branch (EHB), similar to HD 188112. The comparison with different evolutionary tracks suggests a mass between ∼0.18 and ∼0.25 M⊙, too low to sustain core helium burning. If the mass was close to 0.18–0.19 M⊙, the star could be already on the final He-core WD cooling track. A higher mass, up to ∼0.25 M⊙, would be compatible with a He-core WD progenitor undergoing a cooling phase in a H-shell flash loop. A third possibility, with a mass between ∼0.32 and ∼0.40 M⊙, cannot be excluded and would imply that the sdB is a ‘normal’ (but with an unusually low mass) EHB star burning He in its core. In all these different scenarios, the system is expected to merge in less than 3.1 Gyr due to gravitational wave radiation.  
dc.format
application/pdf  
dc.language.iso
eng  
dc.publisher
Oxford University Press  
dc.rights
info:eu-repo/semantics/openAccess  
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/  
dc.subject
Close Binaries  
dc.subject
Kic 6614501 (Estrella)  
dc.subject
Subdwarfs  
dc.subject
White Dwarfs  
dc.subject.classification
Astronomía  
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Ciencias Físicas  
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CIENCIAS NATURALES Y EXACTAS  
dc.title
Orbital properties of an unusually low-mass sdB star in a close binary system with a white dwarf  
dc.type
info:eu-repo/semantics/article  
dc.type
info:ar-repo/semantics/artículo  
dc.type
info:eu-repo/semantics/publishedVersion  
dc.date.updated
2016-11-18T15:11:21Z  
dc.journal.volume
424  
dc.journal.pagination
1752-1761  
dc.journal.pais
Reino Unido  
dc.journal.ciudad
Londres  
dc.description.fil
Fil: Silvotti, R.. INAF. Osservatorio Astrofisico di Torino; Italia  
dc.description.fil
Fil: Østensen, R. H. . Instituut voor Sterrenkunde; Bélgica  
dc.description.fil
Fil: Bloemen, S.. Instituut voor Sterrenkunde; Bélgica  
dc.description.fil
Fil: Telting, J. H.. Nordic Optical Telescope; España  
dc.description.fil
Fil: Heber, U.. Dr. Karl Remeis-Observatory & ECAP, Astronomical Inst; Alemania  
dc.description.fil
Fil: Oreiro, R.. Instituto de Astrofísica de Andalucía; España  
dc.description.fil
Fil: Reed, M. D. . Anglo-Australian Observatory; Australia  
dc.description.fil
Fil: Farris, L. E. . Missouri State University. Department of Physics, Astronomy and Materials Science; Estados Unidos  
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Fil: O’Toole, S. J. . Anglo-Australian Observatory; Australia  
dc.description.fil
Fil: Lanteri, L.. INAF. Osservatorio Astrofisico di Torino; Italia  
dc.description.fil
Fil: Degroote, P.. Instituut voor Sterrenkunde; Bélgica  
dc.description.fil
Fil: Hu, H.. The Observatories. Institute of Astronomy; Reino Unido  
dc.description.fil
Fil: Baran, A. S. . Missouri State University. Department of Physics, Astronomy and Materials Science; Estados Unidos  
dc.description.fil
Fil: Hermes, J. J. . University of Texas at Austin; Estados Unidos  
dc.description.fil
Fil: Althaus, Leandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina  
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Fil: Marsh, T. R. . University Of Warwick; Reino Unido  
dc.description.fil
Fil: Charpinet, S.. Université de Toulouse. Laboratoire d’Astrophysique de Toulouse-Tarbes; Francia  
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Fil: Li, J.. National Aeronautics And Space Administration; Estados Unidos  
dc.description.fil
Fil: Morris, R. L. . National Aeronautics And Space Administration; Estados Unidos  
dc.description.fil
Fil: Sanderfer, D. T. . National Aeronautics And Space Administration; Estados Unidos  
dc.journal.title
Monthly Notices Of The Royal Astronomical Society  
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/http://mnras.oxfordjournals.org/content/424/3/1752  
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1111/j.1365-2966.2012.21232.x