A 9-Hr CV With One Outburst in 4 Years of Kepler Data

Abstract

During a visual search through the Kepler main-field lightcurves, we have discovered a cataclysmic variable (CV) that experienced only a single 4-day long outburst over four years, rising to three times the quiescent flux. During the four years of non-outburst data the Kepler photometry of KIC 5608384 exhibits ellipsoidal light variations (`ELV') with a $\sim$12% amplitude and period of 8.7 hours. Follow-up ground-based spectral observations have yielded a high-quality radial velocity curve and the associated mass function. Additionally, H$\alpha$ emission lines were present in the spectra even though these were taken while the source was presumably in quiescence. These emission lines are at least partially eclipsed by the companion K star. We utilize the available constraints of the mass function, the ELV amplitude, Roche-lobe filling condition, and inferred radius of the K star to derive the system masses and orbital inclination angle: $M_{\mathrm{wd}}\simeq 0.46\pm 0.02M_{\odot }$, $M_{\mathrm{K}}\simeq 0.41\pm 0.03M_{\odot }$, and $i\gtrsim 70^{\circ }$. The value of $M_{\mathrm{wd}}$ is the lowest reported for any accreting WD in a cataclysmic variable. We have also run binary evolution models using MESA to infer the most likely parameters of the pre-cataclysmic binary. Using the mass-transfer rates from the model evolution tracks we conclude that although the rates are close to the critical value for accretion disk stability, we expect KIC 5608384 to exhibit dwarf nova outbursts. We also conclude that the accreting white dwarf most likely descended from a hot subdwarf and, most notably, that this binary is one of the first bona fide examples of a progenitor of AM CVn binaries to have evolved through the CV channel.

arXiv comment15 pages, 13 figures, 4 tables; accepted for publication in MNRAS

References in corpus (56)

• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• Gaia Data Release 2: The astrometric solution
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data
• Common Envelope Evolution: Where we stand and how we can move forward
• The disc instability model of dwarf-novae and low-mass X-ray binary transients
• Models of Stars, Brown Dwarfs and Exoplanets
• Spectral Irradiance Calibration in the Infrared. XIV: the Absolute Calibration of 2MASS
• The origin of sdB stars (II)
• Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)
• The Evolution of Cataclysmic Variables as Revealed by their Donor Stars
• The Ages of Stars
• KEPLER's First Rocky Planet: Kepler-10b
• Kepler Eclipsing Binary Stars. I. Catalog and Principal Characterization of 1879 Eclipsing Binaries in the First Data Release
• RVSAO 2.0: Digital Redshifts and Radial Velocities
• Galactic Reddening in 3D from Stellar Photometry - An Improved Map
• Quantifying the Uncertainty in the Orbits of Extrasolar Planets
• Kepler Eclipsing Binary Stars. II. 2165 Eclipsing Binaries in the Second Data Release
• Extending the Nearby Galaxy Heritage with WISE: First Results from the WISE Enhanced Resolution Galaxy Atlas
• An Exploration of the Paradigm for the 2-3 Hour Period Gap in Cataclysmic Variables
• Post-common-envelope binaries from SDSS. XI: The white dwarf mass distributions of CVs and pre-CVs
• Kepler Eclipsing Binary Stars. III. Classification of Kepler Eclipsing Binary Light Curves with Locally Linear Embedding
• Zodiacal Exoplanets in Time (ZEIT) III: A short-period planet orbiting a pre-main-sequence star in the Upper Scorpius OB Association
• Cataclysmic Variable Primary Effective Temperatures: Constraints on Binary Angular Momentum Loss
• The Galactic Population of Low- and Intermediate-Mass X-ray Binaries
• A reanalysis of the Gaia Data Release 2 photometric sensitivity curves using HST/STIS spectrophotometry
• Three in one go: consequential angular momentum loss can solve major problems of CV evolution
• Measuring White Dwarf Accretion Rates via their Effective Temperatures
• Anomalous ultraviolet line flux ratios in the cataclysmic variables 1RXSJ232953.9+062814, CE315, BZ UMa and EY Cyg observed with HST/STIS
• AE Aquarii: how CVs descend from supersoft binaries
• Population Synthesis of Cataclysmic Variables: I. Inclusion of Detailed Nuclear Evolution
• 1RXS J232953.9+062814: A Dwarf Nova with a 64-minute Orbital Period and a Conspicuous Secondary Star
• Likely Transiting Exocomets Detected by Kepler
• Effective Temperatures of Cataclysmic Variable White Dwarfs as a Probe of their Evolution
• Revised Filter Profiles and Zero Points for Broadband Photometry
• Evolution of Cataclysmic Variables and Related Binaries Containing a White-Dwarf
• Empirical Constraints on Trojan Companions and Orbital Eccentricities in 25 Transiting Exoplanetary Systems
• Dynamical masses, absolute radii and 3D orbits of the triply eclipsing star HD 181068 from Kepler photometry
• One thousand cataclysmic variables from the Catalina Real-time Transient Survey
• Tracking the Stellar Longitudes of Starspots in Short-Period Kepler Binaries
• QZ Serpentis: A Dwarf Nova with a 2-Hour Orbital Period and an Anomalously Hot, Bright Secondary Star
• EPIC 220204960: A Quadruple Star System Containing Two Strongly Interacting Eclipsing Binaries
• The long period Intermediate Polar 1RXSJ154814.5-452845
• Optical Studies of 15 Hard X-ray Selected Cataclysmic Binaries
• EPIC 219217635: A Doubly Eclipsing Quadruple System Containing an Evolved Binary
• SDSSJ001153.08-064739.2, a cataclysmic variable with an evolved donor in the period gap
• Spectroscopic Orbital Periods for 29 Cataclysmic Variables from the Sloan Digital Sky Survey
• An evolved donor star in the long-period cataclysmic variable HS 0218+3229
• Deep GALEX UV Survey of the Kepler Field I: Point Source Catalog
• K-Band Spectroscopy of (Pre-)Cataclysmic Variables: Are Some Donor Stars Really Carbon Poor?
• Phase-Resolved Spectroscopy of Gaia14aae: Line Emission From Near the White Dwarf Surface
• The Identification of Hydrogen-Deficient Cataclysmic Variable Donor Stars
• Occultations from an active accretion disk in a 72 day detached post-Algol system detected by K2
• Astro2020 Science White Paper: Understanding the evolution of close white dwarf binaries

Cited by in corpus (10)

• Towards a volumetric census of close white dwarf binaries I.Reference samples
• V1460 Her: A fast spinning white dwarf accreting from an evolved donor star
• Galactic Model Parameters and Space Density of Cataclysmic Variables in Gaia Era: New Constraints to Population Models
• Reversing the verdict: Cataclysmic variables could be the dominant progenitors of AM CVn binaries after all
• LAMOST J0140355+392651: An evolved cataclysmic variable donor transitioning to become an extremely low mass white dwarf
• Periodic X-ray sources in the Massive Globular Cluster 47 Tucanae: Evidence for Dynamically Formed Cataclysmic Variables
• Dynamical Modeling of CXOGBS J175553.2-281633: A 10 Hour Long Orbital Period Cataclysmic Variable
• 1RXH J082623.6-505741: a new long-period cataclysmic variable with an evolved donor and a low mass transfer rate
• J1832.4-1627, the first eclipsing stream-fed intermediate polar
• The Visual Survey Group: A Decade of Hunting Exoplanets and Unusual Stellar Events with Space-Based Telescopes