GW Librae: A unique laboratory for pulsations in an accreting white dwarf

Abstract

Non-radial pulsations have been identified in a number of accreting white dwarfs in cataclysmic variables. These stars offer insight into the excitation of pulsation modes in atmospheres with mixed compositions of hydrogen, helium, and metals, and the response of these modes to changes in the white dwarf temperature. Among all pulsating cataclysmic variable white dwarfs, GW Librae stands out by having a well-established observational record of three independent pulsation modes that disappeared when the white dwarf temperature rose dramatically following its 2007 accretion outburst. Our analysis of HST ultraviolet spectroscopy taken in 2002, 2010 and 2011, showed that pulsations produce variations in the white dwarf effective temperature as predicted by theory. Additionally in May~2013, we obtained new HST/COS ultraviolet observations that displayed unexpected behaviour: besides showing variability at ~275s, which is close to the post-outburst pulsations detected with HST in 2010 and 2011, the white dwarf exhibits high-amplitude variability on a ~4.4h time-scale. We demonstrate that this variability is produced by an increase of the temperature of a region on white dwarf covering up to ~30 per cent of the visible white dwarf surface. We argue against a short-lived accretion episode as the explanation of such heating, and discuss this event in the context of non-radial pulsations on a rapidly rotating star

arXiv comment11 pages, 8 figures, 2 tables, accpted in MNRAS

References in corpus (39)

• emcee: The MCMC Hammer
• A Comprehensive Spectroscopic Analysis of DB White Dwarfs
• A Spectroscopic Survey & Analysis of Bright, Hydrogen-Rich White Dwarfs
• Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
• Cataclysmic Variable Primary Effective Temperatures: Constraints on Binary Angular Momentum Loss
• Theoretical Modeling of the Thermal State of Accreting White Dwarfs Undergoing Classical Novae
• Parallax and Distance Estimates for Fourteen Cataclysmic Variable Stars
• Population Synthesis of Cataclysmic Variables: I. Inclusion of Detailed Nuclear Evolution
• Far-ultraviolet Spectroscopy of Magnetic Cataclysmic Variables
• Ensemble Characteristics of the ZZ Ceti stars
• HST Spectra of GW Librae: A Hot Pulsating White Dwarf in a Cataclysmic Variable
• The Nonradially-Pulsating Primary of the Cataclysmic Variable GW Librae
• The Dwarf Novae of Shortest Period
• Solution to the problem of the surface gravity distribution of cool DA white dwarfs from improved 3D model atmospheres
• Pulsational Instabilities in Accreting White Dwarfs
• FUSE and HST/STIS far-ultraviolet observations of AM Herculis in an extended low state
• Mode identification from time-resolved spectroscopy of the pulsating white dwarf G 29-38
• KIC 4552982: Outbursts and Asteroseismology from the Longest Pseudo-Continuous Light Curve of a ZZ Ceti
• The accreting white dwarfs in BW Scl, BC UMa and SW UMa
• An XMM-Newton timing analysis of the eclipsing polar DP Leo
• Finding the Instability Strip for Accreting Pulsating White Dwarfs from HST and Optical Observations
• A second case of outbursts in a pulsating white dwarf observed by Kepler
• White Dwarf Heating and Subsequent Cooling in Dwarf Nova Outbursts
• Partial Field Opening and Current Sheet Formation in the Disk Magnetosphere
• Late Superhumps in WZ Sge-Type Dwarf Novae
• Far Ultraviolet Observations of the Dwarf Nova VW Hyi in Quiescence
• ULTRACAM observations of two accreting white dwarf pulsators
• A Far Ultraviolet Archival Study of Cataclysmic Variables: I. FUSE and HST/STIS Spectra of the Exposed White Dwarf in Dwarf Nova Systems
• A 2.09-h Photometric Periodicity in GW Librae
• HST and Optical Data Reveal White Dwarf Cooling, Spin and Periodicities in GW Librae 3-4 Years after Outburst
• The mass of the white dwarf in GW Libra
• The Effect of a Superoutburst on the White Dwarf and Disk of VW Hydri as observed with FUSE
• GALEX and Optical Observations of GW Librae During the Long Decline from Superoutburst
• FS Aur - a new class of Cataclysmic Variables or the missing link between Intermediate Polars and SW Sex objects?
• XMM-Newton Observations of the Cataclysmic Variable GW Lib
• Analyzing the Low State of EF Eridani with Hubble Space Telescope Ultraviolet Spectra
• Steps towards a solution of the FS Aurigae puzzle. II. Confirmation of the intermediate polar status
• The post-outburst pulsations of the accreting white dwarf in the cataclysmic variable GW Librae
• Seismology of Rapidly Rotating Accreting White Dwarfs

Cited by in corpus (13)

• A Volume Limited Sample of Cataclysmic Variables from $Gaia$ DR2: Space Density and Population Properties
• Pulsating white dwarfs: new insights
• Constraining the Evolution of Cataclysmic Variables via the Masses and Accretion Rates of their Underlying White Dwarfs
• Effective Temperatures of Cataclysmic Variable White Dwarfs as a Probe of their Evolution
• Evidence for mass accretion driven by spiral shocks onto the white dwarf in SDSS J123813.73-033933.0
• Superhumps linked to X-ray emission. The superoutbursts of SSS J122221.7-311525 and GW Lib
• R-mode oscillations in accreting white dwarfs in cataclysmic variables
• GW Librae: Still Hot Eight Years Post-Outburst
• Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis
• The C/N ratio from FUV spectroscopy as a constraint upon the past evolution of HS0218+3229
• NGTS and HST insights into the long period modulation in GW Librae
• The Heating and Pulsations of V386 Serpentis after its 2019 Dwarf Nova Outburst
• Bridging the Gap: OPTICAM Reveals the Hidden Spin of the WZ Sge Star GOTO 065054.49+593624.51