The orbits of subdwarf B + main-sequence binaries: I. the sdB+G0 system PG 1104+243

J. Vos; R. H. Østensen; P. Degroote; K. De Smedt; E. M. Green; U. Heber; H. Van Winckel; B. Acke; S. Bloemen; P. De Cat; K. Exter; P. Lampens; R. Lombaert; T. Masseron; J. Menu; P. Neyskens; G. Raskin; E. Ringat; T. Rauch; K. Smolders; A. Tkachenko

doi:10.1051/0004-6361/201219723

The orbits of subdwarf B + main-sequence binaries: I. the sdB+G0 system PG 1104+243

J. Vos, R. H. Østensen, P. Degroote, K. De Smedt, E. M. Green, U. Heber, H. Van Winckel, B. Acke, S. Bloemen, P. De Cat, K. Exter, P. Lampens, R. Lombaert, T. Masseron, J. Menu, P. Neyskens, G. Raskin, E. Ringat, T. Rauch, K. SmoldersA. Tkachenko

Steward Observatory

Research output: Contribution to journal › Article › peer-review

43 Scopus citations

Abstract

Context. The predicted orbital period histogram of a subdwarf B (sdB) population is bimodal with a peak at short (<10 days) and long (>250 days) periods. Observationally, however, there are many short-period sdB systems known, but only very few long-period sdB binaries are identified. As these predictions are based on poorly understood binary interaction processes, it is of prime importance to confront the predictions to well constrained observational data. We therefore initiated a monitoring program to find and characterize long-period sdB stars. Aims. In this contribution we aim to determine the absolute dimensions of the long-period binary system PG 1104+243 consisting of an sdB and a main-sequence (MS) component, and determine its evolution history. Methods. High-resolution spectroscopy time-series were obtained with HERMES at the Mercator telescope at La Palma, and analyzed to determine the radial velocities of both the sdB and MS components. Photometry from the literature was used to construct the spectral energy distribution (SED) of the binary. Atmosphere models were used to fit this SED and determine the surface gravity and temperature of both components. The gravitational redshift provided an independent confirmation of the surface gravity of the sdB component. Results. An orbital period of 753 ± 3 d and a mass ratio of q = 0.637 ± 0.015 were found for PG 1104+243 from the radial velocity curves. The sdB component has an effective temperature of T_eff = 33 500 ± 1200 K and a surface gravity of log g = 5.84 ± 0.08 dex, while the cool companion is found to be a G-type star with T_eff = 5930 ± 160 K and log g = 4.29 ± 0.05 dex. When a canonical mass of M_sdB = 0.47 M_· is assumed, the MS component has a mass of M_MS = 0.74 ± 0.07 M_·, and its temperature corresponds to what is expected for a terminal age main-sequence star with sub-solar metalicity. Conclusions. PG 1104+243 is the first long-period sdB binary in which accurate and consistent physical parameters of both components could be determined, and the first sdB binary in which the gravitational redshift is measured. Furthermore, PG 1104+243 is the first sdB+MS system that shows consistent evidence for being formed through stable Roche-lobe overflow. An analysis of a larger sample of long-period sdB binaries will allow for the refinement of several essential parameters in the current formation channels.

Original language	English (US)
Article number	A6
Journal	Astronomy and astrophysics
Volume	548
DOIs	https://doi.org/10.1051/0004-6361/201219723
State	Published - 2012

Keywords

Binaries: spectroscopic
Stars: evolution
Stars: fundamental parameters
Subdwarfs

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/201219723

Cite this

Vos, J., Østensen, R. H., Degroote, P., De Smedt, K., Green, E. M., Heber, U., Van Winckel, H., Acke, B., Bloemen, S., De Cat, P., Exter, K., Lampens, P., Lombaert, R., Masseron, T., Menu, J., Neyskens, P., Raskin, G., Ringat, E., Rauch, T., ... Tkachenko, A. (2012). The orbits of subdwarf B + main-sequence binaries: I. the sdB+G0 system PG 1104+243. Astronomy and astrophysics, 548, Article A6. https://doi.org/10.1051/0004-6361/201219723

Vos, J, Østensen, RH, Degroote, P, De Smedt, K, Green, EM, Heber, U, Van Winckel, H, Acke, B, Bloemen, S, De Cat, P, Exter, K, Lampens, P, Lombaert, R, Masseron, T, Menu, J, Neyskens, P, Raskin, G, Ringat, E, Rauch, T, Smolders, K & Tkachenko, A 2012, 'The orbits of subdwarf B + main-sequence binaries: I. the sdB+G0 system PG 1104+243', Astronomy and astrophysics, vol. 548, A6. https://doi.org/10.1051/0004-6361/201219723

@article{6eb3abdcf8734b39975f6ccab20edf3a,

title = "The orbits of subdwarf B + main-sequence binaries: I. the sdB+G0 system PG 1104+243",

abstract = "Context. The predicted orbital period histogram of a subdwarf B (sdB) population is bimodal with a peak at short (<10 days) and long (>250 days) periods. Observationally, however, there are many short-period sdB systems known, but only very few long-period sdB binaries are identified. As these predictions are based on poorly understood binary interaction processes, it is of prime importance to confront the predictions to well constrained observational data. We therefore initiated a monitoring program to find and characterize long-period sdB stars. Aims. In this contribution we aim to determine the absolute dimensions of the long-period binary system PG 1104+243 consisting of an sdB and a main-sequence (MS) component, and determine its evolution history. Methods. High-resolution spectroscopy time-series were obtained with HERMES at the Mercator telescope at La Palma, and analyzed to determine the radial velocities of both the sdB and MS components. Photometry from the literature was used to construct the spectral energy distribution (SED) of the binary. Atmosphere models were used to fit this SED and determine the surface gravity and temperature of both components. The gravitational redshift provided an independent confirmation of the surface gravity of the sdB component. Results. An orbital period of 753 ± 3 d and a mass ratio of q = 0.637 ± 0.015 were found for PG 1104+243 from the radial velocity curves. The sdB component has an effective temperature of Teff = 33 500 ± 1200 K and a surface gravity of log g = 5.84 ± 0.08 dex, while the cool companion is found to be a G-type star with Teff = 5930 ± 160 K and log g = 4.29 ± 0.05 dex. When a canonical mass of MsdB = 0.47 M· is assumed, the MS component has a mass of MMS = 0.74 ± 0.07 M·, and its temperature corresponds to what is expected for a terminal age main-sequence star with sub-solar metalicity. Conclusions. PG 1104+243 is the first long-period sdB binary in which accurate and consistent physical parameters of both components could be determined, and the first sdB binary in which the gravitational redshift is measured. Furthermore, PG 1104+243 is the first sdB+MS system that shows consistent evidence for being formed through stable Roche-lobe overflow. An analysis of a larger sample of long-period sdB binaries will allow for the refinement of several essential parameters in the current formation channels.",

keywords = "Binaries: spectroscopic, Stars: evolution, Stars: fundamental parameters, Subdwarfs",

author = "J. Vos and {\O}stensen, {R. H.} and P. Degroote and {De Smedt}, K. and Green, {E. M.} and U. Heber and {Van Winckel}, H. and B. Acke and S. Bloemen and {De Cat}, P. and K. Exter and P. Lampens and R. Lombaert and T. Masseron and J. Menu and P. Neyskens and G. Raskin and E. Ringat and T. Rauch and K. Smolders and A. Tkachenko",

note = "Funding Information: We thank the referee for his useful suggestions. Many thanks to N. Cox, N. Gorlova and C. Waelkens for their help with obtaining spectra at the Mercator Telescope. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof{\ng}sica de Canarias. Based on observations obtained with the HERMES spectrograph, which is supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of K.U. Leuven, Belgium, the Fonds National Recherches Scientific (FNRS), Belgium, the Royal Observatory of Belgium, the Observatoire de Genve, Switzerland and the Thringer Landessternwarte Tautenburg, Germany. Some of the observations reported in this paper were obtained at the MMT Observatory, a facility operated jointly by the University of Arizona and the Smithsonian Institution. The following Internet-based resources were used in research for this paper: the NASA Astrophysics Data System; the SIMBAD database and the VizieR service operated by CDS, Strasbourg, France; the arχive scientific paper preprint service operated by Cornell University. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The research leading to these results has received funding from the European Research Council under the European Community{\textquoteright}s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement No. 227224 ( prosperity ), as well as from the Research Council of K.U. Leuven grant agreement GOA/2008/04, the German Aerospace Center (DLR) under grant agreement 05OR0806 and the Deutsche Forschungsgemeinschaft under grant agreement WE1312/41-1. P. Neyskens is Boursier FRIA, funded by the Fonds National Recherches Scientific.",

year = "2012",

doi = "10.1051/0004-6361/201219723",

language = "English (US)",

volume = "548",

journal = "Astronomy and astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - The orbits of subdwarf B + main-sequence binaries

T2 - I. the sdB+G0 system PG 1104+243

AU - Vos, J.

AU - Østensen, R. H.

AU - Degroote, P.

AU - De Smedt, K.

AU - Green, E. M.

AU - Heber, U.

AU - Van Winckel, H.

AU - Acke, B.

AU - Bloemen, S.

AU - De Cat, P.

AU - Exter, K.

AU - Lampens, P.

AU - Lombaert, R.

AU - Masseron, T.

AU - Menu, J.

AU - Neyskens, P.

AU - Raskin, G.

AU - Ringat, E.

AU - Rauch, T.

AU - Smolders, K.

AU - Tkachenko, A.

N1 - Funding Information: We thank the referee for his useful suggestions. Many thanks to N. Cox, N. Gorlova and C. Waelkens for their help with obtaining spectra at the Mercator Telescope. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofŋsica de Canarias. Based on observations obtained with the HERMES spectrograph, which is supported by the Fund for Scientific Research of Flanders (FWO), Belgium, the Research Council of K.U. Leuven, Belgium, the Fonds National Recherches Scientific (FNRS), Belgium, the Royal Observatory of Belgium, the Observatoire de Genve, Switzerland and the Thringer Landessternwarte Tautenburg, Germany. Some of the observations reported in this paper were obtained at the MMT Observatory, a facility operated jointly by the University of Arizona and the Smithsonian Institution. The following Internet-based resources were used in research for this paper: the NASA Astrophysics Data System; the SIMBAD database and the VizieR service operated by CDS, Strasbourg, France; the arχive scientific paper preprint service operated by Cornell University. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The research leading to these results has received funding from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007–2013)/ERC grant agreement No. 227224 ( prosperity ), as well as from the Research Council of K.U. Leuven grant agreement GOA/2008/04, the German Aerospace Center (DLR) under grant agreement 05OR0806 and the Deutsche Forschungsgemeinschaft under grant agreement WE1312/41-1. P. Neyskens is Boursier FRIA, funded by the Fonds National Recherches Scientific.

PY - 2012

Y1 - 2012

N2 - Context. The predicted orbital period histogram of a subdwarf B (sdB) population is bimodal with a peak at short (<10 days) and long (>250 days) periods. Observationally, however, there are many short-period sdB systems known, but only very few long-period sdB binaries are identified. As these predictions are based on poorly understood binary interaction processes, it is of prime importance to confront the predictions to well constrained observational data. We therefore initiated a monitoring program to find and characterize long-period sdB stars. Aims. In this contribution we aim to determine the absolute dimensions of the long-period binary system PG 1104+243 consisting of an sdB and a main-sequence (MS) component, and determine its evolution history. Methods. High-resolution spectroscopy time-series were obtained with HERMES at the Mercator telescope at La Palma, and analyzed to determine the radial velocities of both the sdB and MS components. Photometry from the literature was used to construct the spectral energy distribution (SED) of the binary. Atmosphere models were used to fit this SED and determine the surface gravity and temperature of both components. The gravitational redshift provided an independent confirmation of the surface gravity of the sdB component. Results. An orbital period of 753 ± 3 d and a mass ratio of q = 0.637 ± 0.015 were found for PG 1104+243 from the radial velocity curves. The sdB component has an effective temperature of Teff = 33 500 ± 1200 K and a surface gravity of log g = 5.84 ± 0.08 dex, while the cool companion is found to be a G-type star with Teff = 5930 ± 160 K and log g = 4.29 ± 0.05 dex. When a canonical mass of MsdB = 0.47 M· is assumed, the MS component has a mass of MMS = 0.74 ± 0.07 M·, and its temperature corresponds to what is expected for a terminal age main-sequence star with sub-solar metalicity. Conclusions. PG 1104+243 is the first long-period sdB binary in which accurate and consistent physical parameters of both components could be determined, and the first sdB binary in which the gravitational redshift is measured. Furthermore, PG 1104+243 is the first sdB+MS system that shows consistent evidence for being formed through stable Roche-lobe overflow. An analysis of a larger sample of long-period sdB binaries will allow for the refinement of several essential parameters in the current formation channels.

AB - Context. The predicted orbital period histogram of a subdwarf B (sdB) population is bimodal with a peak at short (<10 days) and long (>250 days) periods. Observationally, however, there are many short-period sdB systems known, but only very few long-period sdB binaries are identified. As these predictions are based on poorly understood binary interaction processes, it is of prime importance to confront the predictions to well constrained observational data. We therefore initiated a monitoring program to find and characterize long-period sdB stars. Aims. In this contribution we aim to determine the absolute dimensions of the long-period binary system PG 1104+243 consisting of an sdB and a main-sequence (MS) component, and determine its evolution history. Methods. High-resolution spectroscopy time-series were obtained with HERMES at the Mercator telescope at La Palma, and analyzed to determine the radial velocities of both the sdB and MS components. Photometry from the literature was used to construct the spectral energy distribution (SED) of the binary. Atmosphere models were used to fit this SED and determine the surface gravity and temperature of both components. The gravitational redshift provided an independent confirmation of the surface gravity of the sdB component. Results. An orbital period of 753 ± 3 d and a mass ratio of q = 0.637 ± 0.015 were found for PG 1104+243 from the radial velocity curves. The sdB component has an effective temperature of Teff = 33 500 ± 1200 K and a surface gravity of log g = 5.84 ± 0.08 dex, while the cool companion is found to be a G-type star with Teff = 5930 ± 160 K and log g = 4.29 ± 0.05 dex. When a canonical mass of MsdB = 0.47 M· is assumed, the MS component has a mass of MMS = 0.74 ± 0.07 M·, and its temperature corresponds to what is expected for a terminal age main-sequence star with sub-solar metalicity. Conclusions. PG 1104+243 is the first long-period sdB binary in which accurate and consistent physical parameters of both components could be determined, and the first sdB binary in which the gravitational redshift is measured. Furthermore, PG 1104+243 is the first sdB+MS system that shows consistent evidence for being formed through stable Roche-lobe overflow. An analysis of a larger sample of long-period sdB binaries will allow for the refinement of several essential parameters in the current formation channels.

KW - Binaries: spectroscopic

KW - Stars: evolution

KW - Stars: fundamental parameters

KW - Subdwarfs

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UR - http://www.scopus.com/inward/citedby.url?scp=84869194197&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201219723

DO - 10.1051/0004-6361/201219723

M3 - Article

AN - SCOPUS:84869194197

SN - 0004-6361

VL - 548

JO - Astronomy and astrophysics

JF - Astronomy and astrophysics

M1 - A6

ER -

The orbits of subdwarf B + main-sequence binaries: I. the sdB+G0 system PG 1104+243

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