(2021) NGTS and HST insights into the long-period modulation in GW Librae. Monthly Notices of the Royal Astronomical Society, 502 (1). pp. 581-588. doi:10.1093/mnras/staa4015 ISSN 1745-3933.

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Abstract

Light curves of the accreting white dwarf pulsator GW Librae spanning a 7.5-month period in 2017 were obtained as part of the Next-Generation Transit Survey. This data set comprises 787 h of photometry from 148 clear nights, allowing the behaviour of the long (hours) and short-period (20 min) modulation signals to be tracked from night to night over a much longer observing baseline than has been previously achieved. The long-period modulations intermittently detected in previous observations of GW Lib are found to be a persistent feature, evolving between states with periods ≃ 83 min and 2–4 h on time-scales of several days. The 20 min signal is found to have a broadly stable amplitude and frequency for the duration of the campaign, but the previously noted phase instability is confirmed. Ultraviolet observations obtained with the Cosmic Origin Spectrograph on-board the Hubble Space Telescope constrain the ultraviolet-to-optical flux ratio to ≃5 for the 4 h modulation, and ≲1 for the 20 min period, with caveats introduced by non-simultaneous observations. These results add further observational evidence that these enigmatic signals must originate from the white dwarf, highlighting our continued gap in theoretical understanding of the mechanisms that drive them.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science, Engineering and Medicine > Science > Physics
Library of Congress Subject Headings (LCSH):	Dwarf novae , White dwarf stars , Pulsating stars
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	Oxford University Press
ISSN:	1745-3933
Official Date:	March 2021
Dates:	Date Event March 2021 Published 11 January 2021 Available 18 December 2020 Accepted
Volume:	502
Number:	1
Page Range:	pp. 581-588
DOI:	10.1093/mnras/staa4015
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Date of first compliant deposit:	28 February 2021
Date of first compliant Open Access:	2 March 2021
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID ST/M001962/1 [STFC] Science and Technology Facilities Council http://dx.doi.org/10.13039/501100000271 ST/S002642/1 [STFC] Science and Technology Facilities Council http://dx.doi.org/10.13039/501100000271 FP/2007- 2013 Seventh Framework Programme http://dx.doi.org/10.13039/100011102 320964 (WDTracer) European Research Council http://dx.doi.org/10.13039/501100000781 ST/L000733/1 [STFC] Science and Technology Facilities Council http://dx.doi.org/10.13039/501100000271 ST/P000495/1 [STFC] Science and Technology Facilities Council http://dx.doi.org/10.13039/501100000271 AST-1514737. National Science Foundation http://dx.doi.org/10.13039/501100008982
Open Access Version:	ArXiv

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