Brown-Sevilla, S. B., Nascimbeni, V., Borsato, L., Tartaglia, L., Nardiello, D., Granata, V., Libralato, M., Damasso, M., Piotto, G., Pollacco, D. , West, Richard G., Colombo, L. S., Cunial, A., Piazza, G. and Scaggiante, F. (2021) A new photometric and dynamical study of the eclipsing binary star HW Virginis. Monthly Notices of the Royal Astronomical Society, 506 (2). pp. 2122-2135. doi:10.1093/mnras/stab1843 ISSN 1365-2966.

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Abstract

A growing number of eclipsing binary systems of the ‘HW Virginis’ (HW Vir) kind (i.e. composed by a subdwarf-B/O primary star and an M dwarf secondary) show variations in their orbital period, also called eclipse time variations (ETVs). Their physical origin is not yet known with certainty: While some ETVs have been claimed to arise from dynamical perturbations due to the presence of circumbinary planetary companions, other authors suggest that the Applegate effect or other unknown stellar mechanisms could be responsible for them. In this work, we present 28 unpublished high-precision light curves of one of the most controversial of these systems, the prototype HW Vir. We homogeneously analysed the new eclipse timings together with historical data obtained between 1983 and 2012, demonstrating that the planetary models previously claimed do not fit the new photometric data, besides being dynamically unstable. In an effort to find a new model able to fit all the available data, we developed a new approach based on a global-search genetic algorithm and eventually found two new distinct families of solutions that fit the observed timings very well, yet dynamically unstable at the 105-yr time-scale. This serves as a cautionary tale on the existence of formal solutions that apparently explain ETVs but are not physically meaningful, and on the need of carefully testing their stability. On the other hand, our data confirm the presence of an ETV on HW Vir that known stellar mechanisms are unable to explain, pushing towards further observing and modeling efforts.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science, Engineering and Medicine > Science > Physics
SWORD Depositor:	Library Publications Router
Library of Congress Subject Headings (LCSH):	Eclipsing binaries -- Orbits, Astronomical photometry, Planetary systems
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	Oxford University Press (OUP)
ISSN:	1365-2966
Official Date:	September 2021
Dates:	Date Event September 2021 Published 2 July 2021 Available 24 June 2021 Accepted
Volume:	506
Number:	2
Page Range:	pp. 2122-2135
DOI:	10.1093/mnras/stab1843
Status:	Peer Reviewed
Publication Status:	Published
Reuse Statement (publisher, data, author rights):	This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2022 © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Access rights to Published version:	Restricted or Subscription Access
Date of first compliant deposit:	17 June 2022
Date of first compliant Open Access:	17 June 2022
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID 2013-016-R.0 Agenzia Spaziale Italiana http://dx.doi.org/10.13039/501100003981 20179ZF5KS Ministero dell’Istruzione, dell’Università e della Ricerca http://dx.doi.org/10.13039/501100003407 UNSPECIFIED Centre National d’Etudes Spatiales http://dx.doi.org/10.13039/501100002830
Related URLs:	https://academic.oup.com/journals/pages/...

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