Year: 2021
Type: article
Abstract: 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.
Institutions: University of Warwick, Naresuan University, University of Leicester, Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), Boston University, Centro de Astrofísica y Tecnologías Afines, University of Chile, University of Washington, National Astronomical Research Institute of Thailand, University of North Carolina at Chapel Hill
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, National Astronomical Research Institute of Thailand, European Commission, Science and Technology Facilities Council, Comisión Nacional de Investigación Científica y Tecnológica, FP7 Ideas: European Research Council
Awards: The Next Generation Transit Survey (NGTS): Operations 2019-2022, White Dwarfs as Tracers of Stellar, Binary and Planetary Evolution, Warwick Astronomy and Astrophysics Consolidated Grant 2020-2023, G2202886080, G2222488238, G2981143, G3207356259, Understanding Interacting Binary Stars Identified in Astronomical Surveys, The Next Generation Transit Survey (NGTS): Deployment and Operations, G3985250707, G4242332828, G433322167, G4518818167, The Next Generation Transit Survey (NGTS) : Deployment and Operations, G58316358, G5878965429, G600531842, G6273510985, G6396559207, G642528487, Warwick Astronomy and Astrophysics Consolidated Grant 2017-2020, G767601387, Warwick Astrophysics Consolidated Grant 2014-2017, G8210229802, Irradiated atmospheres of brown dwarfs: providing an insight into exoplanet atmospheres, G878044590, G896728979
OpenAlex ID: W3122842804