Maxted, P.F.L., Serenelli, A.M., Marsh, T.R. et al. (3 more authors) (2014) WASP 1628+10-an EL CVn-type binary with a very low mass stripped red giant star and multiperiodic pulsations. Monthly Notices of the Royal Astronomical Society, 444 (1). pp. 208-216. ISSN 0035-8711
Abstract
The star 1SWASP J162842.31+101416.7 (WASP 1628+10) is one of several EL CVn-type stars recently identified using the Wide Angle Search for Planets (WASP) data base, i.e. an eclipsing binary star in which an A-type dwarf star (WASP 1628+10 A) eclipses the remnant of a disrupted red giant star (WASP 1628+10 B). We have measured the masses, radii and luminosities of the stars in WASP 1628+10 using photometry obtained in three bands (u , g , r ) with the ULTRACAM instrument and medium-resolution spectroscopy. The properties of the remnant are well matched by models for stars in a rarely observed state evolving to higher effective temperatures at nearly constant luminosity prior to becoming a very low mass white dwarf composed almost entirely of helium, i.e. we confirm that WASP 1628+10 B is a precursor of a helium white dwarf (pre-He-WD). WASP 1628+10 A appears to be a normal A2 V star with a mass of 1.36 ± 0.05 M. By fitting models to the spectrum of this star around the Hγ line we find that it has an effective temperature Teff, A = 7500 ± 200 K and a metallicity [Fe/H] = −0.3 ± 0.3. The mass of WASP 1628+10 B is only 0.135 ± 0.02 M. The effective temperature of this pre-He-WD is approximately 9200 K. The ULTRACAM photometry of WASP 1628+10 shows variability at several frequencies around 40 cycles d−1, which is typical for δ Sct-type pulsations often observed in early A-type stars like WASP 1628+10 A. We also observe frequencies near 114 and 129 cycles d−1, much higher than the frequencies normally seen in δ Sct stars. Additional photometry through the primary eclipse will be required to confirm that these higher frequencies are due to pulsations in WASP 1628+10 B. If confirmed, this would be only the second known example of a pre-He-WD showing high-frequency pulsations.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | binaries: close; binaries: eclipsing; binaries: spectroscopic; stars: individual: 1SWASP J162842.31+101416.7 |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/J001589/1 SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/M001350/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 27 Oct 2017 08:40 |
Last Modified: | 27 Oct 2017 08:45 |
Published Version: | https://doi.org/10.1093/mnras/stu1465 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1093/mnras/stu1465 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:122728 |